==================================
内建模板标签和过滤器
==================================

此文档介绍了 Django 内贱的模板标签和过滤器. 在此建议您使用 :doc:`自动化文档
</ref/contrib/admin/admindocs>`, 如果他是可用的, 那么他还包含了自定义的模板标签和过滤器.

.. _ref-templates-builtins-tags:

内建标签参考
----------------------

.. highlightlang:: html+django

.. templatetag:: autoescape

autoescape
^^^^^^^^^^

控制当前使用的自动转义行为.
这个标签带有 ``on`` 或 ``off`` 参数, 决定了块内是否自动转义.
该块由 ``endautoescape`` 标签结束.

当自动转义是生效的, 所有变量的内容将被自动转义成HTML字面值后输出(在这之前,其他的过滤器均被执行).
这等效于在所有变量上应用了 :tfilter:`escape` 过滤器.

唯一的例外是已被标记为"安全"的转义, 如由代码生成的变量,
或者使用了 :tfilter:`safe` 或 :tfilter:`escape` 过滤器.

简单的应用::

    {% autoescape on %}
        {{ body }}
    {% endautoescape %}

.. templatetag:: block

block
^^^^^

定义一个块, 可以被子模板覆盖. 参见 :ref:`模板继承 <template-inheritance>`.

.. templatetag:: comment

comment
^^^^^^^

注释掉 ``{% comment %}`` 和 ``{% endcomment %}`` 之间的所有内容.

.. templatetag:: csrf_token

csrf_token
^^^^^^^^^^

在 Django 1.1.X 中, 这是一个未定义的标签他返回一个空字符串以便向后兼容.
在 Django 1.2 和更高的版本中, 它使用了CSRF保护, 具体描述在这个文档中
:doc:`Cross Site Request Forgeries </ref/contrib/csrf>`.

.. templatetag:: cycle

cycle
^^^^^

在遇到此标签时周期性的显示给定的字符串或变量.

在循环中, 当每经过一次循环, 就周期性的显示给定的字符串中的一个::

    {% for o in some_list %}
        <tr class="{% cycle 'row1' 'row2' %}">
            ...
        </tr>
    {% endfor %}

你也可以使用变量. 例如, 如果你有这两个模板变量,
``rowvalue1`` 和 ``rowvalue2``, 你可以像这样在这两个变量之间循环的输出其中一个::

    {% for o in some_list %}
        <tr class="{% cycle rowvalue1 rowvalue2 %}">
            ...
        </tr>
    {% endfor %}

请注意, 可变参数 (上面的 ``rowvalue1`` 和 ``rowvalue2``) **不会** 被自动转义!
所以你应当确保变量是安全的, 或者使用强制转义, 像这样::

    {% for o in some_list %}
        <tr class="{% filter force_escape %}{% cycle rowvalue1 rowvalue2 %}{% endfilter %}">
            ...
        </tr>
    {% endfor %}

您可以混合使用变量和字符串::

    {% for o in some_list %}
        <tr class="{% cycle 'row1' rowvalue2 'row3' %}">
            ...
        </tr>
    {% endfor %}

在某些情况下, 你可能想要在循环之外使用一些周期性变化的变量.
为了做到这点, 只需要给 ``{% cycle %}`` 标签使用"as"定义一个名字, 像这样::

    {% cycle 'row1' 'row2' as rowcolors %}

从这里开始, 你就可以在模板中使用这个变量了.
当你想显示这个周期性变量的下一个值的时候, 只需要插入你之前定义好的变量名就可以了.
所以, 像下面这个模板::

    <tr>
        <td class="{% cycle 'row1' 'row2' as rowcolors %}">...</td>
        <td class="{{ rowcolors }}">...</td>
    </tr>
    <tr>
        <td class="{% cycle rowcolors %}">...</td>
        <td class="{{ rowcolors }}">...</td>
    </tr>

将会输出::

    <tr>
        <td class="row1">...</td>
        <td class="row1">...</td>
    </tr>
    <tr>
        <td class="row2">...</td>
        <td class="row2">...</td>
    </tr>

你可以在 ``{% cycle %}`` 标签中使用任意数量的参数, 使用空格作为分隔.
如果一个参数被单引号(``'``)或者双引号(``"``)包围, 那么他将被当做是一个字符串.
如果不带引号, 则被视为一个模板变量.

请注意, 在循环中包含的变量将不会被转义. 这是因为模板标签没有转义他们的内容.
任何HTML或JavaScript代码将被渲染为原始值. 这有可能导致安全问题.

``{% cycle %}`` 标签在较早的Django版本中使用的语法和现在有很大的差别.
为了向后兼容, 你不应该在新的项目中使用这种语法, 但是还是有人会使用, 像下面这样::

    {% cycle row1,row2,row3 %}

在这种语法中, 每个参数都被当做是一个字符串, 没有办法使用变量作为参数.
逗号和空格也无法被作为参数.
我们提到任何新的项目, 你不应该使用这个语法吗?

.. versionadded:: 1.3

默认情况下, 当您使用 ``as`` 关键字标记cycle标签,
在使用 ``{% cycle %}`` 声明时将输出周期中的第一个值.
如果你想使用一个嵌套的循环或模板中的值, 这可能是一个问题.
如果你想只声明周期, 但不输出第一个值,
你可以添加一个 ``silent`` 关键字作为标签中的最后一个关键字.
例如::

    {% for obj in some_list %}
        {% cycle 'row1' 'row2' as rowcolors silent %}
        <tr class="{{ rowcolors }}">{% include "subtemplate.html " %}</tr>
    {% endfor %}

这将在 ``<tr>`` 的 ``class`` 属性上循环的输出 ``row1`` 和 ``row2``;
子模板将会被 ``rowcolors`` 变量所标记的 ``<tr>`` 包围.
如果没有使用 ``silent`` 关键字, ``row1`` 将会在 ``<tr>`` 元素之前被输出.

当silent关键字被使用在一个周期变量上, silent关键字也被自动的使用在了后续的这个变量上.
在下面这个模板中, 第二个 ``{% cycle %}`` 将不会输出任何值::

    {% cycle 'row1' 'row2' as rowcolors silent %}
    {% cycle rowcolors %}

.. templatetag:: debug

debug
^^^^^

输出整体的调试信息, 包括当前上下文和导入的模块.

.. templatetag:: extends

extends
^^^^^^^

标记此模板继承的父模板的标签.

这个标签有两种使用方式:

* ``{% extends "base.html" %}`` (使用引号) Django将使用字面值
  ``"base.html"`` 作为所继承的父模板的名字.

* ``{% extends variable %}`` 使用变量 ``variable``. 如果变量是一个字符串,
  Django会使用这个字符串作为所继承的父模板的名字.
  如果变量是一个 ``Template`` 对象, Django会使用这个对象作为父模板.

更多内容请参见 :ref:`template-inheritance` 文档.

.. templatetag:: filter

filter
^^^^^^

Filters the contents of the variable through variable filters.

Filters can also be piped through each other, and they can have arguments --
just like in variable syntax.

Sample usage::

    {% filter force_escape|lower %}
        This text will be HTML-escaped, and will appear in all lowercase.
    {% endfilter %}

.. note::

    The :tfilter:`escape` and :tfilter:`safe` filters are not acceptable
    arguments. Instead, use the :ttag:`autoescape` tag to manage autoescaping
    for blocks of template code.

.. templatetag:: firstof

firstof
^^^^^^^

Outputs the first variable passed that is not False. Does NOT auto-escape
variable values.

Outputs nothing if all the passed variables are False.

Sample usage::

    {% firstof var1 var2 var3 %}

This is equivalent to::

    {% if var1 %}
        {{ var1|safe }}
    {% else %}{% if var2 %}
        {{ var2|safe }}
    {% else %}{% if var3 %}
        {{ var3|safe }}
    {% endif %}{% endif %}{% endif %}

You can also use a literal string as a fallback value in case all
passed variables are False::

    {% firstof var1 var2 var3 "fallback value" %}

Note that the variables included in the firstof tag will not be
escaped. This is because template tags do not escape their content.
Any HTML or Javascript code contained in the printed variable will be
rendered as-is, which could potentially lead to security issues. If you
need to escape the variables in the firstof tag, you must do so
explicitly::

    {% filter force_escape %}
        {% firstof var1 var2 var3 "fallback value" %}
    {% endfilter %}

.. templatetag:: for

for
^^^

Loop over each item in an array.  For example, to display a list of athletes
provided in ``athlete_list``::

    <ul>
    {% for athlete in athlete_list %}
        <li>{{ athlete.name }}</li>
    {% endfor %}
    </ul>

You can loop over a list in reverse by using
``{% for obj in list reversed %}``.

If you need to loop over a list of lists, you can unpack the values
in each sub-list into individual variables. For example, if your context
contains a list of (x,y) coordinates called ``points``, you could use the
following to output the list of points::

    {% for x, y in points %}
        There is a point at {{ x }},{{ y }}
    {% endfor %}

This can also be useful if you need to access the items in a dictionary.
For example, if your context contained a dictionary ``data``, the following
would display the keys and values of the dictionary::

    {% for key, value in data.items %}
        {{ key }}: {{ value }}
    {% endfor %}

The for loop sets a number of variables available within the loop:

==========================  ===============================================
Variable                    Description
==========================  ===============================================
``forloop.counter``         The current iteration of the loop (1-indexed)
``forloop.counter0``        The current iteration of the loop (0-indexed)
``forloop.revcounter``      The number of iterations from the end of the
                            loop (1-indexed)
``forloop.revcounter0``     The number of iterations from the end of the
                            loop (0-indexed)
``forloop.first``           True if this is the first time through the loop
``forloop.last``            True if this is the last time through the loop
``forloop.parentloop``      For nested loops, this is the loop "above" the
                            current one
==========================  ===============================================

for ... empty
^^^^^^^^^^^^^

The ``for`` tag can take an optional ``{% empty %}`` clause that will be
displayed if the given array is empty or could not be found::

    <ul>
    {% for athlete in athlete_list %}
        <li>{{ athlete.name }}</li>
    {% empty %}
        <li>Sorry, no athlete in this list!</li>
    {% endfor %}
    <ul>

The above is equivalent to -- but shorter, cleaner, and possibly faster
than -- the following::

    <ul>
      {% if athlete_list %}
        {% for athlete in athlete_list %}
          <li>{{ athlete.name }}</li>
        {% endfor %}
      {% else %}
        <li>Sorry, no athletes in this list.</li>
      {% endif %}
    </ul>

.. templatetag:: if

if
^^

The ``{% if %}`` tag evaluates a variable, and if that variable is "true" (i.e.
exists, is not empty, and is not a false boolean value) the contents of the
block are output::

    {% if athlete_list %}
        Number of athletes: {{ athlete_list|length }}
    {% elif athlete_in_locker_room_list %}
        Athletes should be out of the locker room soon!
    {% else %}
        No athletes.
    {% endif %}

In the above, if ``athlete_list`` is not empty, the number of athletes will be
displayed by the ``{{ athlete_list|length }}`` variable.

As you can see, the ``if`` tag may take one or several `` {% elif %}``
clauses, as well as an ``{% else %}`` clause that will be displayed if all
previous conditions fail. These clauses are optional.

.. versionadded:: 1.4

The ``if`` tag now supports ``{% elif %}`` clauses.

Boolean operators
^^^^^^^^^^^^^^^^^

:ttag:`if` tags may use ``and``, ``or`` or ``not`` to test a number of
variables or to negate a given variable::

    {% if athlete_list and coach_list %}
        Both athletes and coaches are available.
    {% endif %}

    {% if not athlete_list %}
        There are no athletes.
    {% endif %}

    {% if athlete_list or coach_list %}
        There are some athletes or some coaches.
    {% endif %}

    {% if not athlete_list or coach_list %}
        There are no athletes or there are some coaches (OK, so
        writing English translations of boolean logic sounds
        stupid; it's not our fault).
    {% endif %}

    {% if athlete_list and not coach_list %}
        There are some athletes and absolutely no coaches.
    {% endif %}

.. versionchanged:: 1.2

Use of both ``and`` and ``or`` clauses within the same tag is allowed, with
``and`` having higher precedence than ``or`` e.g.::

    {% if athlete_list and coach_list or cheerleader_list %}

will be interpreted like:

.. code-block:: python

    if (athlete_list and coach_list) or cheerleader_list

Use of actual brackets in the :ttag:`if` tag is invalid syntax.  If you need
them to indicate precedence, you should use nested :ttag:`if` tags.

.. versionadded:: 1.2


:ttag:`if` tags may also use the operators ``==``, ``!=``, ``<``, ``>``,
``<=``, ``>=`` and ``in`` which work as follows:


``==`` operator
^^^^^^^^^^^^^^^

Equality. Example::

    {% if somevar == "x" %}
      This appears if variable somevar equals the string "x"
    {% endif %}

``!=`` operator
^^^^^^^^^^^^^^^

Inequality. Example::

    {% if somevar != "x" %}
      This appears if variable somevar does not equal the string "x",
      or if somevar is not found in the context
    {% endif %}

``<`` operator
^^^^^^^^^^^^^^

Less than. Example::

    {% if somevar < 100 %}
      This appears if variable somevar is less than 100.
    {% endif %}

``>`` operator
^^^^^^^^^^^^^^

Greater than. Example::

    {% if somevar > 0 %}
      This appears if variable somevar is greater than 0.
    {% endif %}

``<=`` operator
^^^^^^^^^^^^^^^

Less than or equal to. Example::

    {% if somevar <= 100 %}
      This appears if variable somevar is less than 100 or equal to 100.
    {% endif %}

``>=`` operator
^^^^^^^^^^^^^^^

Greater than or equal to. Example::

    {% if somevar >= 1 %}
      This appears if variable somevar is greater than 1 or equal to 1.
    {% endif %}

``in`` operator
^^^^^^^^^^^^^^^

Contained within. This operator is supported by many Python containers to test
whether the given value is in the container.  The following are some examples
of how ``x in y`` will be interpreted::

    {% if "bc" in "abcdef" %}
      This appears since "bc" is a substring of "abcdef"
    {% endif %}

    {% if "hello" in greetings %}
      If greetings is a list or set, one element of which is the string
      "hello", this will appear.
    {% endif %}

    {% if user in users %}
      If users is a QuerySet, this will appear if user is an
      instance that belongs to the QuerySet.
    {% endif %}

``not in`` operator
^^^^^^^^^^^^^^^^^^^

Not contained within.  This is the negation of the ``in`` operator.


The comparison operators cannot be 'chained' like in Python or in mathematical
notation. For example, instead of using::

    {% if a > b > c %}  (WRONG)

you should use::

    {% if a > b and b > c %}


Filters
^^^^^^^

You can also use filters in the :ttag:`if` expression. For example::

    {% if messages|length >= 100 %}
       You have lots of messages today!
    {% endif %}

Complex expressions
^^^^^^^^^^^^^^^^^^^

All of the above can be combined to form complex expressions. For such
expressions, it can be important to know how the operators are grouped when the
expression is evaluated - that is, the precedence rules.  The precedence of the
operators, from lowest to highest, is as follows:

* ``or``
* ``and``
* ``not``
* ``in``
* ``==``, ``!=``, ``<``, ``>``, ``<=``, ``>=``

(This follows Python exactly). So, for example, the following complex
:ttag:`if` tag:

.. code-block:: django

    {% if a == b or c == d and e %}

...will be interpreted as:

.. code-block:: python

    (a == b) or ((c == d) and e)

If you need different precedence, you will need to use nested :ttag:`if` tags.
Sometimes that is better for clarity anyway, for the sake of those who do not
know the precedence rules.


.. templatetag:: ifchanged

ifchanged
^^^^^^^^^

Check if a value has changed from the last iteration of a loop.

The ``{% ifchanged %}`` block tag is used within a loop. It has two possible
uses.

1. Checks its own rendered contents against its previous state and only
   displays the content if it has changed. For example, this displays a list of
   days, only displaying the month if it changes::

        <h1>Archive for {{ year }}</h1>

        {% for date in days %}
            {% ifchanged %}<h3>{{ date|date:"F" }}</h3>{% endifchanged %}
            <a href="{{ date|date:"M/d"|lower }}/">{{ date|date:"j" }}</a>
        {% endfor %}

2. If given one or more variables, check whether any variable has changed.
   For example, the following shows the date every time it changes, while
   showing the hour if either the hour or the date has changed::

        {% for date in days %}
            {% ifchanged date.date %} {{ date.date }} {% endifchanged %}
            {% ifchanged date.hour date.date %}
                {{ date.hour }}
            {% endifchanged %}
        {% endfor %}

The ``ifchanged`` tag can also take an optional ``{% else %}`` clause that
will be displayed if the value has not changed::

        {% for match in matches %}
            <div style="background-color:
                {% ifchanged match.ballot_id %}
                    {% cycle "red" "blue" %}
                {% else %}
                    grey
                {% endifchanged %}
            ">{{ match }}</div>
        {% endfor %}

.. templatetag:: ifequal

ifequal
^^^^^^^

Output the contents of the block if the two arguments equal each other.

Example::

    {% ifequal user.id comment.user_id %}
        ...
    {% endifequal %}

As in the :ttag:`if` tag, an ``{% else %}`` clause is optional.

The arguments can be hard-coded strings, so the following is valid::

    {% ifequal user.username "adrian" %}
        ...
    {% endifequal %}

It is only possible to compare an argument to template variables or strings.
You cannot check for equality with Python objects such as ``True`` or
``False``.  If you need to test if something is true or false, use the
:ttag:`if` tag instead.

.. versionadded:: 1.2
   An alternative to the ``ifequal`` tag is to use the :ttag:`if` tag and the
   ``==`` operator.

.. templatetag:: ifnotequal

ifnotequal
^^^^^^^^^^

Just like :ttag:`ifequal`, except it tests that the two arguments are not
equal.

.. versionadded:: 1.2
   An alternative to the ``ifnotequal`` tag is to use the :ttag:`if` tag and
   the ``!=`` operator.

.. templatetag:: include

include
^^^^^^^

Loads a template and renders it with the current context. This is a way of
"including" other templates within a template.

The template name can either be a variable or a hard-coded (quoted) string,
in either single or double quotes.

This example includes the contents of the template ``"foo/bar.html"``::

    {% include "foo/bar.html" %}

This example includes the contents of the template whose name is contained in
the variable ``template_name``::

    {% include template_name %}

An included template is rendered with the context of the template that's
including it. This example produces the output ``"Hello, John"``:

* Context: variable ``person`` is set to ``"john"``.
* Template::

    {% include "name_snippet.html" %}

* The ``name_snippet.html`` template::

    {{ greeting }}, {{ person|default:"friend" }}!

.. versionchanged:: 1.3
   Additional context and exclusive context.

You can pass additional context to the template using keyword arguments::

    {% include "name_snippet.html" with person="Jane" greeting="Hello" %}

If you want to only render the context with the variables provided (or even
no variables at all), use the ``only`` option::

    {% include "name_snippet.html" with greeting="Hi" only %}

.. note::
    The :ttag:`include` tag should be considered as an implementation of
    "render this subtemplate and include the HTML", not as "parse this
    subtemplate and include its contents as if it were part of the parent".
    This means that there is no shared state between included templates --
    each include is a completely independent rendering process.

See also: :ttag:`{% ssi %}<ssi>`.

.. templatetag:: load

load
^^^^

Loads a custom template tag set.

For example, the following template would load all the tags and filters
registered in ``somelibrary`` and ``otherlibrary`` located in package
``package``::

    {% load somelibrary package.otherlibrary %}

.. versionchanged:: 1.3

You can also selectively load individual filters or tags from a library, using
the ``from`` argument. In this example, the template tags/filters named ``foo``
and ``bar`` will be loaded from ``somelibrary``::

    {% load foo bar from somelibrary %}

See :doc:`Custom tag and filter libraries </howto/custom-template-tags>` for
more information.

.. templatetag:: now

now
^^^

Displays the current date and/or time, using a format according to the given
string. Such string can contain format specifiers characters as described
in the :tfilter:`date` filter section.

Example::

    It is {% now "jS F Y H:i" %}

Note that you can backslash-escape a format string if you want to use the
"raw" value. In this example, "f" is backslash-escaped, because otherwise
"f" is a format string that displays the time. The "o" doesn't need to be
escaped, because it's not a format character::

    It is the {% now "jS o\f F" %}

This would display as "It is the 4th of September".

.. versionchanged:: 1.4

.. note::

    The format passed can also be one of the predefined ones
    :setting:`DATE_FORMAT`, :setting:`DATETIME_FORMAT`,
    :setting:`SHORT_DATE_FORMAT` or :setting:`SHORT_DATETIME_FORMAT`.
    The predefined formats may vary depending on the current locale and
    if :ref:`format-localization` is enabled, e.g.::

        It is {% now "SHORT_DATETIME_FORMAT" %}

.. templatetag:: regroup

regroup
^^^^^^^

Regroups a list of alike objects by a common attribute.

This complex tag is best illustrated by use of an example: say that ``people``
is a list of people represented by dictionaries with ``first_name``,
``last_name``, and ``gender`` keys:

.. code-block:: python

    people = [
        {'first_name': 'George', 'last_name': 'Bush', 'gender': 'Male'},
        {'first_name': 'Bill', 'last_name': 'Clinton', 'gender': 'Male'},
        {'first_name': 'Margaret', 'last_name': 'Thatcher', 'gender': 'Female'},
        {'first_name': 'Condoleezza', 'last_name': 'Rice', 'gender': 'Female'},
        {'first_name': 'Pat', 'last_name': 'Smith', 'gender': 'Unknown'},
    ]

...and you'd like to display a hierarchical list that is ordered by gender,
like this:

* Male:

  * George Bush
  * Bill Clinton

* Female:

  * Margaret Thatcher
  * Condoleezza Rice

* Unknown:

  * Pat Smith

You can use the ``{% regroup %}`` tag to group the list of people by gender.
The following snippet of template code would accomplish this::

    {% regroup people by gender as gender_list %}

    <ul>
    {% for gender in gender_list %}
        <li>{{ gender.grouper }}
        <ul>
            {% for item in gender.list %}
            <li>{{ item.first_name }} {{ item.last_name }}</li>
            {% endfor %}
        </ul>
        </li>
    {% endfor %}
    </ul>

Let's walk through this example. ``{% regroup %}`` takes three arguments: the
list you want to regroup, the attribute to group by, and the name of the
resulting list. Here, we're regrouping the ``people`` list by the ``gender``
attribute and calling the result ``gender_list``.

``{% regroup %}`` produces a list (in this case, ``gender_list``) of
**group objects**. Each group object has two attributes:

* ``grouper`` -- the item that was grouped by (e.g., the string "Male" or
  "Female").
* ``list`` -- a list of all items in this group (e.g., a list of all people
  with gender='Male').

Note that ``{% regroup %}`` does not order its input! Our example relies on
the fact that the ``people`` list was ordered by ``gender`` in the first place.
If the ``people`` list did *not* order its members by ``gender``, the
regrouping would naively display more than one group for a single gender. For
example, say the ``people`` list was set to this (note that the males are not
grouped together):

.. code-block:: python

    people = [
        {'first_name': 'Bill', 'last_name': 'Clinton', 'gender': 'Male'},
        {'first_name': 'Pat', 'last_name': 'Smith', 'gender': 'Unknown'},
        {'first_name': 'Margaret', 'last_name': 'Thatcher', 'gender': 'Female'},
        {'first_name': 'George', 'last_name': 'Bush', 'gender': 'Male'},
        {'first_name': 'Condoleezza', 'last_name': 'Rice', 'gender': 'Female'},
    ]

With this input for ``people``, the example ``{% regroup %}`` template code
above would result in the following output:

* Male:

  * Bill Clinton

* Unknown:

  * Pat Smith

* Female:

  * Margaret Thatcher

* Male:

  * George Bush

* Female:

  * Condoleezza Rice

The easiest solution to this gotcha is to make sure in your view code that the
data is ordered according to how you want to display it.

Another solution is to sort the data in the template using the
:tfilter:`dictsort` filter, if your data is in a list of dictionaries::

    {% regroup people|dictsort:"gender" by gender as gender_list %}


Grouping on other properties
^^^^^^^^^^^^^^^^^^^^^^^^^^^^

Any valid template lookup is a legal grouping attribute for the regroup
tag, including methods, attributes, dictionary keys and list items. For
example, if the "gender" field is a foreign key to a class with
an attribute "description," you could use::

    {% regroup people by gender.description as gender_list %}

Or, if ``gender`` is a field with ``choices``, it will have a
:meth:`^django.db.models.Model.get_FOO_display` method available as an
attribute, allowing  you to group on the display string rather than the
``choices`` key::

    {% regroup people by get_gender_display as gender_list %}

``{{ gender.grouper }}`` will now display the value fields from the
``choices`` set rather than the keys.

.. templatetag:: spaceless

spaceless
^^^^^^^^^

Removes whitespace between HTML tags. This includes tab
characters and newlines.

Example usage::

    {% spaceless %}
        <p>
            <a href="foo/">Foo</a>
        </p>
    {% endspaceless %}

This example would return this HTML::

    <p><a href="foo/">Foo</a></p>

Only space between *tags* is removed -- not space between tags and text. In
this example, the space around ``Hello`` won't be stripped::

    {% spaceless %}
        <strong>
            Hello
        </strong>
    {% endspaceless %}

.. templatetag:: ssi

ssi
^^^

Outputs the contents of a given file into the page.

Like a simple :ttag:`include` tag, ``{% ssi %}`` includes the contents of
another file -- which must be specified using an absolute path -- in the
current page::

    {% ssi /home/html/ljworld.com/includes/right_generic.html %}

If the optional "parsed" parameter is given, the contents of the included
file are evaluated as template code, within the current context::

    {% ssi /home/html/ljworld.com/includes/right_generic.html parsed %}

Note that if you use ``{% ssi %}``, you'll need to define
:setting:`ALLOWED_INCLUDE_ROOTS` in your Django settings, as a security
measure.

See also: :ttag:`{% include %}<include>`.

.. admonition:: Forwards compatibility

    .. versionchanged:: 1.3

    In Django 1.5, the behavior of the :ttag:`ssi` template tag will
    change, with the first argument being made into a context
    variable, rather than being a special case unquoted constant. This
    will allow the :ttag:`ssi` tag to use a context variable as the
    value of the page to be included.

    In order to provide a forwards compatibility path, Django 1.3
    provides a future compatibility library -- ``future`` -- that
    implements the new behavior. To use this library, add a
    :ttag:`load` call at the top of any template using the :ttag:`ssi`
    tag, and wrap the first argument to the :ttag:`ssi` tag in quotes.
    For example::

        {% load ssi from future %}
        {% ssi '/home/html/ljworld.com/includes/right_generic.html' %}

    In Django 1.5, the unquoted constant behavior will be replaced
    with the behavior provided by the ``future`` tag library.
    Existing templates should be migrated to use the new syntax.

.. templatetag:: templatetag

templatetag
^^^^^^^^^^^

Outputs one of the syntax characters used to compose template tags.

Since the template system has no concept of "escaping", to display one of the
bits used in template tags, you must use the ``{% templatetag %}`` tag.

The argument tells which template bit to output:

==================  =======
Argument            Outputs
==================  =======
``openblock``       ``{%``
``closeblock``      ``%}``
``openvariable``    ``{{``
``closevariable``   ``}}``
``openbrace``       ``{``
``closebrace``      ``}``
``opencomment``     ``{#``
``closecomment``    ``#}``
==================  =======

.. templatetag:: url

url
^^^

Returns an absolute path reference (a URL without the domain name) matching a
given view function and optional parameters. This is a way to output links
without violating the DRY principle by having to hard-code URLs in your
templates::

    {% url path.to.some_view v1 v2 %}

The first argument is a path to a view function in the format
``package.package.module.function``. Additional arguments are optional and
should be space-separated values that will be used as arguments in the URL.
The example above shows passing positional arguments. Alternatively you may
use keyword syntax::

    {% url path.to.some_view arg1=v1 arg2=v2 %}

Do not mix both positional and keyword syntax in a single call. All arguments
required by the URLconf should be present.

For example, suppose you have a view, ``app_views.client``, whose URLconf
takes a client ID (here, ``client()`` is a method inside the views file
``app_views.py``). The URLconf line might look like this:

.. code-block:: python

    ('^client/(\d+)/$', 'app_views.client')

If this app's URLconf is included into the project's URLconf under a path
such as this:

.. code-block:: python

    ('^clients/', include('project_name.app_name.urls'))

...then, in a template, you can create a link to this view like this::

    {% url app_views.client client.id %}

The template tag will output the string ``/clients/client/123/``.

If you're using :ref:`named URL patterns <naming-url-patterns>`, you can
refer to the name of the pattern in the ``url`` tag instead of using the
path to the view.

Note that if the URL you're reversing doesn't exist, you'll get an
:exc:`^django.core.urlresolvers.NoReverseMatch` exception raised, which will
cause your site to display an error page.

If you'd like to retrieve a URL without displaying it, you can use a slightly
different call::


    {% url path.to.view arg arg2 as the_url %}

    <a href="{{ the_url }}">I'm linking to {{ the_url }}</a>

This ``{% url ... as var %}`` syntax will *not* cause an error if the view is
missing. In practice you'll use this to link to views that are optional::

    {% url path.to.view as the_url %}
    {% if the_url %}
      <a href="{{ the_url }}">Link to optional stuff</a>
    {% endif %}

If you'd like to retrieve a namespaced URL, specify the fully qualified name::

    {% url myapp:view-name %}

This will follow the normal :ref:`namespaced URL resolution strategy
<topics-http-reversing-url-namespaces>`, including using any hints provided
by the context as to the current application.

.. versionchanged:: 1.2

For backwards compatibility, the ``{% url %}`` tag also supports the
use of commas to separate arguments. You shouldn't use this in any new
projects, but for the sake of the people who are still using it,
here's what it looks like::

    {% url path.to.view arg,arg2 %}
    {% url path.to.view arg, arg2 %}

This syntax doesn't support the use of literal commas, or equals
signs. Did we mention you shouldn't use this syntax in any new
projects?

.. admonition:: Forwards compatibility

    .. versionchanged:: 1.3

    In Django 1.5, the behavior of the :ttag:`url` template tag will
    change, with the first argument being made into a context
    variable, rather than being a special case unquoted constant. This
    will allow the :ttag:`url` tag to use a context variable as the
    value of the URL name to be reversed.

    In order to provide a forwards compatibility path, Django 1.3
    provides a future compatibility library -- ``future`` -- that
    implements the new behavior. To use this library, add a
    :ttag:`load` call at the top of any template using the :ttag:`url`
    tag, and wrap the first argument to the :ttag:`url` tag in quotes.
    For example::

        {% load url from future %}


        {% url 'app_views.client' %}

        {% url 'myapp:view-name' %}

        {% with view_path="app_views.client" %}
        {% url view_path client.id %}
        {% endwith %}

        {% with url_name="client-detail-view" %}
        {% url url_name client.id %}
        {% endwith %}

    The new library also drops support for the comma syntax for
    separating arguments to the :ttag:`url` template tag.

    In Django 1.5, the old behavior will be replaced with the behavior
    provided by the ``future`` tag library. Existing templates be
    migrated to use the new syntax.

.. templatetag:: widthratio

widthratio
^^^^^^^^^^

For creating bar charts and such, this tag calculates the ratio of a given
value to a maximum value, and then applies that ratio to a constant.

For example::

    <img src="bar.gif" height="10" width="{% widthratio this_value max_value 100 %}" />

Above, if ``this_value`` is 175 and ``max_value`` is 200, the image in the
above example will be 88 pixels wide (because 175/200 = .875; .875 * 100 = 87.5
which is rounded up to 88).

.. templatetag:: with

with
^^^^

.. versionchanged:: 1.3
   New keyword argument format and multiple variable assignments.

Caches a complex variable under a simpler name. This is useful when accessing
an "expensive" method (e.g., one that hits the database) multiple times.

For example::

    {% with total=business.employees.count %}
        {{ total }} employee{{ total|pluralize }}
    {% endwith %}

The populated variable (in the example above, ``total``) is only available
between the ``{% with %}`` and ``{% endwith %}`` tags.

You can assign more than one context variable::

    {% with alpha=1 beta=2 %}
        ...
    {% endwith %}

.. note:: The previous more verbose format is still supported:
   ``{% with business.employees.count as total %}``

.. _ref-templates-builtins-filters:

Built-in filter reference
-------------------------

.. templatefilter:: add

add
^^^

Adds the argument to the value.

For example::

    {{ value|add:"2" }}

If ``value`` is ``4``, then the output will be ``6``.

.. versionchanged:: 1.2
   The following behavior didn't exist in previous Django versions.

This filter will first try to coerce both values to integers. If this fails,
it'll attempt to add the values together anyway. This will work on some data
types (strings, list, etc.) and fail on others. If it fails, the result will
be an empty string.

For example, if we have::

    {{ first|add:second }}

and ``first`` is ``[1, 2, 3]`` and ``second`` is ``[4, 5, 6]``, then the
output will be ``[1, 2, 3, 4, 5, 6]``.

.. warning::

    Strings that can be coerced to integers will be **summed**, not
    concatenated, as in the first example above.

.. templatefilter:: addslashes

addslashes
^^^^^^^^^^

Adds slashes before quotes. Useful for escaping strings in CSV, for example.

For example::

    {{ value|addslashes }}

If ``value`` is ``"I'm using Django"``, the output will be
``"I\'m using Django"``.

.. templatefilter:: capfirst

capfirst
^^^^^^^^

Capitalizes the first character of the value.

For example::

    {{ value|capfirst }}

If ``value`` is ``"django"``, the output will be ``"Django"``.

.. templatefilter:: center

center
^^^^^^

Centers the value in a field of a given width.

For example::

    "{{ value|center:"15" }}"

If ``value`` is ``"Django"``, the output will be ``"     Django    "``.

.. templatefilter:: cut

cut
^^^

Removes all values of arg from the given string.

For example::

    {{ value|cut:" "}}

If ``value`` is ``"String with spaces"``, the output will be
``"Stringwithspaces"``.

.. templatefilter:: date

date
^^^^

Formats a date according to the given format.

Uses a similar format as PHP's ``date()`` function (http://php.net/date)
with some differences.

Available format strings:

================  ========================================  =====================
Format character  Description                               Example output
================  ========================================  =====================
a                 ``'a.m.'`` or ``'p.m.'`` (Note that       ``'a.m.'``
                  this is slightly different than PHP's
                  output, because this includes periods
                  to match Associated Press style.)
A                 ``'AM'`` or ``'PM'``.                     ``'AM'``
b                 Month, textual, 3 letters, lowercase.     ``'jan'``
B                 Not implemented.
c                 ISO 8601 format. (Note: unlike others     ``2008-01-02T10:30:00.000123+02:00``,
                  formatters, such as "Z", "O" or "r",      or ``2008-01-02T10:30:00.000123`` if the datetime is naive
                  the "c" formatter will not add timezone
                  offset if value is a naive datetime
                  (see :class:`datetime.tzinfo`).
d                 Day of the month, 2 digits with           ``'01'`` to ``'31'``
                  leading zeros.
D                 Day of the week, textual, 3 letters.      ``'Fri'``
e                 Timezone name. Could be in any format,
                  or might return an empty string,          ``''``, ``'GMT'``, ``'-500'``, ``'US/Eastern'``, etc.
                  depending on the datetime.
E                 Month, locale specific alternative
                  representation usually used for long
                  date representation.                      ``'listopada'`` (for Polish locale, as opposed to ``'Listopad'``)
f                 Time, in 12-hour hours and minutes,       ``'1'``, ``'1:30'``
                  with minutes left off if they're zero.
                  Proprietary extension.
F                 Month, textual, long.                     ``'January'``
g                 Hour, 12-hour format without leading      ``'1'`` to ``'12'``
                  zeros.
G                 Hour, 24-hour format without leading      ``'0'`` to ``'23'``
                  zeros.
h                 Hour, 12-hour format.                     ``'01'`` to ``'12'``
H                 Hour, 24-hour format.                     ``'00'`` to ``'23'``
i                 Minutes.                                  ``'00'`` to ``'59'``
I                 Not implemented.
j                 Day of the month without leading          ``'1'`` to ``'31'``
                  zeros.
l                 Day of the week, textual, long.           ``'Friday'``
L                 Boolean for whether it's a leap year.     ``True`` or ``False``
m                 Month, 2 digits with leading zeros.       ``'01'`` to ``'12'``
M                 Month, textual, 3 letters.                ``'Jan'``
n                 Month without leading zeros.              ``'1'`` to ``'12'``
N                 Month abbreviation in Associated Press    ``'Jan.'``, ``'Feb.'``, ``'March'``, ``'May'``
                  style. Proprietary extension.
o                 ISO-8601 week-numbering year,             ``'1999'``
                  corresponding to
                  the ISO-8601 week number (W)
O                 Difference to Greenwich time in hours.    ``'+0200'``
P                 Time, in 12-hour hours, minutes and       ``'1 a.m.'``, ``'1:30 p.m.'``, ``'midnight'``, ``'noon'``, ``'12:30 p.m.'``
                  'a.m.'/'p.m.', with minutes left off
                  if they're zero and the special-case
                  strings 'midnight' and 'noon' if
                  appropriate. Proprietary extension.
r                 :rfc:`2822` formatted date.               ``'Thu, 21 Dec 2000 16:01:07 +0200'``
s                 Seconds, 2 digits with leading zeros.     ``'00'`` to ``'59'``
S                 English ordinal suffix for day of the     ``'st'``, ``'nd'``, ``'rd'`` or ``'th'``
                  month, 2 characters.
t                 Number of days in the given month.        ``28`` to ``31``
T                 Time zone of this machine.                ``'EST'``, ``'MDT'``
u                 Microseconds.                             ``0`` to ``999999``
U                 Seconds since the Unix Epoch
                  (January 1 1970 00:00:00 UTC).
w                 Day of the week, digits without           ``'0'`` (Sunday) to ``'6'`` (Saturday)
                  leading zeros.
W                 ISO-8601 week number of year, with        ``1``, ``53``
                  weeks starting on Monday.
y                 Year, 2 digits.                           ``'99'``
Y                 Year, 4 digits.                           ``'1999'``
z                 Day of the year.                          ``0`` to ``365``
Z                 Time zone offset in seconds. The          ``-43200`` to ``43200``
                  offset for timezones west of UTC is
                  always negative, and for those east of
                  UTC is always positive.
================  ========================================  =====================

.. versionadded:: 1.2

The ``c`` and ``u`` format specification characters were added in Django 1.2.

.. versionadded:: 1.4

The ``e`` and ``o`` format specification characters were added in Django 1.4.

For example::

    {{ value|date:"D d M Y" }}

If ``value`` is a ``datetime`` object (e.g., the result of
``datetime.datetime.now()``), the output will be the string
``'Wed 09 Jan 2008'``.

The format passed can be one of the predefined ones :setting:`DATE_FORMAT`,
:setting:`DATETIME_FORMAT`, :setting:`SHORT_DATE_FORMAT` or
:setting:`SHORT_DATETIME_FORMAT`, or a custom format that uses the format
specifiers shown in the table above. Note that predefined formats may vary
depending on the current locale.

Assuming that :setting:`USE_L10N` is ``True`` and :setting:`LANGUAGE_CODE` is,
for example, ``"es"``, then for::

    {{ value|date:"SHORT_DATE_FORMAT" }}

the output would be the string ``"09/01/2008"`` (the ``"SHORT_DATE_FORMAT"``
format specifier for the ``es`` locale as shipped with Django is ``"d/m/Y"``).

When used without a format string::

    {{ value|date }}

...the formatting string defined in the :setting:`DATE_FORMAT` setting will be
used, without applying any localization.

.. versionchanged:: 1.2
    Predefined formats can now be influenced by the current locale.

.. templatefilter:: default

default
^^^^^^^

If value evaluates to ``False``, uses the given default. Otherwise, uses the
value.

For example::

    {{ value|default:"nothing" }}

If ``value`` is ``""`` (the empty string), the output will be ``nothing``.

.. templatefilter:: default_if_none

default_if_none
^^^^^^^^^^^^^^^

If (and only if) value is ``None``, uses the given default. Otherwise, uses the
value.

Note that if an empty string is given, the default value will *not* be used.
Use the :tfilter:`default` filter if you want to fallback for empty strings.

For example::

    {{ value|default_if_none:"nothing" }}

If ``value`` is ``None``, the output will be the string ``"nothing"``.

.. templatefilter:: dictsort

dictsort
^^^^^^^^

Takes a list of dictionaries and returns that list sorted by the key given in
the argument.

For example::

    {{ value|dictsort:"name" }}

If ``value`` is:

.. code-block:: python

    [
        {'name': 'zed', 'age': 19},
        {'name': 'amy', 'age': 22},
        {'name': 'joe', 'age': 31},
    ]

then the output would be:

.. code-block:: python

    [
        {'name': 'amy', 'age': 22},
        {'name': 'joe', 'age': 31},
        {'name': 'zed', 'age': 19},
    ]

.. templatefilter:: dictsortreversed

dictsortreversed
^^^^^^^^^^^^^^^^

Takes a list of dictionaries and returns that list sorted in reverse order by
the key given in the argument. This works exactly the same as the above filter,
but the returned value will be in reverse order.

.. templatefilter:: divisibleby

divisibleby
^^^^^^^^^^^

Returns ``True`` if the value is divisible by the argument.

For example::

    {{ value|divisibleby:"3" }}

If ``value`` is ``21``, the output would be ``True``.

.. templatefilter:: escape

escape
^^^^^^

Escapes a string's HTML. Specifically, it makes these replacements:

* ``<`` is converted to ``&lt;``
* ``>`` is converted to ``&gt;``
* ``'`` (single quote) is converted to ``&#39;``
* ``"`` (double quote) is converted to ``&quot;``
* ``&`` is converted to ``&amp;``

The escaping is only applied when the string is output, so it does not matter
where in a chained sequence of filters you put ``escape``: it will always be
applied as though it were the last filter. If you want escaping to be applied
immediately, use the :tfilter:`force_escape` filter.

Applying ``escape`` to a variable that would normally have auto-escaping
applied to the result will only result in one round of escaping being done. So
it is safe to use this function even in auto-escaping environments. If you want
multiple escaping passes to be applied, use the :tfilter:`force_escape` filter.

.. templatefilter:: escapejs

escapejs
^^^^^^^^

Escapes characters for use in JavaScript strings. This does *not* make the
string safe for use in HTML, but does protect you from syntax errors when using
templates to generate JavaScript/JSON.

For example::

    {{ value|escapejs }}

If ``value`` is ``"testing\r\njavascript \'string" <b>escaping</b>"``,
the output will be ``"testing\\u000D\\u000Ajavascript \\u0027string\\u0022 \\u003Cb\\u003Eescaping\\u003C/b\\u003E"``.

.. templatefilter:: filesizeformat

filesizeformat
^^^^^^^^^^^^^^

Formats the value like a 'human-readable' file size (i.e. ``'13 KB'``,
``'4.1 MB'``, ``'102 bytes'``, etc).

For example::

    {{ value|filesizeformat }}

If ``value`` is 123456789, the output would be ``117.7 MB``.

.. templatefilter:: first

first
^^^^^

Returns the first item in a list.

For example::

    {{ value|first }}

If ``value`` is the list ``['a', 'b', 'c']``, the output will be ``'a'``.

.. templatefilter:: fix_ampersands

fix_ampersands
^^^^^^^^^^^^^^

.. note::

    This is rarely useful as ampersands are automatically escaped. See
    :tfilter:`escape` for more information.

Replaces ampersands with ``&amp;`` entities.

For example::

    {{ value|fix_ampersands }}

If ``value`` is ``Tom & Jerry``, the output will be ``Tom &amp; Jerry``.

However, ampersands used in named entities and numeric character references
will not be replaced. For example, if ``value`` is ``Caf&eacute;``, the output
will *not* be ``Caf&amp;eacute;`` but remain ``Caf&eacute;``. This means that
in some edge cases, such as acronyms followed by semicolons, this filter will
not replace ampersands that need replacing. For example, if ``value`` is
``Contact the R&D;``, the output will remain unchanged because ``&D;``
resembles a named entity.

.. templatefilter:: floatformat

floatformat
^^^^^^^^^^^

When used without an argument, rounds a floating-point number to one decimal
place -- but only if there's a decimal part to be displayed. For example:

============  ===========================  ========
``value``     Template                     Output
============  ===========================  ========
``34.23234``  ``{{ value|floatformat }}``  ``34.2``
``34.00000``  ``{{ value|floatformat }}``  ``34``
``34.26000``  ``{{ value|floatformat }}``  ``34.3``
============  ===========================  ========

If used with a numeric integer argument, ``floatformat`` rounds a number to
that many decimal places. For example:

============  =============================  ==========
``value``     Template                       Output
============  =============================  ==========
``34.23234``  ``{{ value|floatformat:3 }}``  ``34.232``
``34.00000``  ``{{ value|floatformat:3 }}``  ``34.000``
``34.26000``  ``{{ value|floatformat:3 }}``  ``34.260``
============  =============================  ==========

If the argument passed to ``floatformat`` is negative, it will round a number
to that many decimal places -- but only if there's a decimal part to be
displayed. For example:

============  ================================  ==========
``value``     Template                          Output
============  ================================  ==========
``34.23234``  ``{{ value|floatformat:"-3" }}``  ``34.232``
``34.00000``  ``{{ value|floatformat:"-3" }}``  ``34``
``34.26000``  ``{{ value|floatformat:"-3" }}``  ``34.260``
============  ================================  ==========

Using ``floatformat`` with no argument is equivalent to using ``floatformat``
with an argument of ``-1``.

.. templatefilter:: force_escape

force_escape
^^^^^^^^^^^^

Applies HTML escaping to a string (see the :tfilter:`escape` filter for
details). This filter is applied *immediately* and returns a new, escaped
string. This is useful in the rare cases where you need multiple escaping or
want to apply other filters to the escaped results. Normally, you want to use
the :tfilter:`escape` filter.

.. templatefilter:: get_digit

get_digit
^^^^^^^^^

Given a whole number, returns the requested digit, where 1 is the right-most
digit, 2 is the second-right-most digit, etc. Returns the original value for
invalid input (if input or argument is not an integer, or if argument is less
than 1). Otherwise, output is always an integer.

For example::

    {{ value|get_digit:"2" }}

If ``value`` is ``123456789``, the output will be ``8``.

.. templatefilter:: iriencode

iriencode
^^^^^^^^^

Converts an IRI (Internationalized Resource Identifier) to a string that is
suitable for including in a URL. This is necessary if you're trying to use
strings containing non-ASCII characters in a URL.

It's safe to use this filter on a string that has already gone through the
:tfilter:`urlencode` filter.

For example::

    {{ value|iriencode }}

If ``value`` is ``"?test=1&me=2"``, the output will be ``"?test=1&amp;me=2"``.

.. templatefilter:: join

join
^^^^

Joins a list with a string, like Python's ``str.join(list)``

For example::

    {{ value|join:" // " }}

If ``value`` is the list ``['a', 'b', 'c']``, the output will be the string
``"a // b // c"``.

.. templatefilter:: last

last
^^^^

Returns the last item in a list.

For example::

    {{ value|last }}

If ``value`` is the list ``['a', 'b', 'c', 'd']``, the output will be the
string ``"d"``.

.. templatefilter:: length

length
^^^^^^

Returns the length of the value. This works for both strings and lists.

For example::

    {{ value|length }}

If ``value`` is ``['a', 'b', 'c', 'd']``, the output will be ``4``.

.. templatefilter:: length_is

length_is
^^^^^^^^^

Returns ``True`` if the value's length is the argument, or ``False`` otherwise.

For example::

    {{ value|length_is:"4" }}

If ``value`` is ``['a', 'b', 'c', 'd']``, the output will be ``True``.

.. templatefilter:: linebreaks

linebreaks
^^^^^^^^^^

Replaces line breaks in plain text with appropriate HTML; a single
newline becomes an HTML line break (``<br />``) and a new line
followed by a blank line becomes a paragraph break (``</p>``).

For example::

    {{ value|linebreaks }}

If ``value`` is ``Joel\nis a slug``, the output will be ``<p>Joel<br />is a
slug</p>``.

.. templatefilter:: linebreaksbr

linebreaksbr
^^^^^^^^^^^^

Converts all newlines in a piece of plain text to HTML line breaks
(``<br />``).

For example::

    {{ value|linebreaksbr }}

If ``value`` is ``Joel\nis a slug``, the output will be ``Joel<br />is a
slug``.

.. templatefilter:: linenumbers

linenumbers
^^^^^^^^^^^

Displays text with line numbers.

For example::

    {{ value|linenumbers }}

If ``value`` is::

    one
    two
    three

the output will be::

    1. one
    2. two
    3. three

.. templatefilter:: ljust

ljust
^^^^^

Left-aligns the value in a field of a given width.

**Argument:** field size

For example::

    "{{ value|ljust:"10" }}"

If ``value`` is ``Django``, the output will be ``"Django    "``.

.. templatefilter:: lower

lower
^^^^^

Converts a string into all lowercase.

For example::

    {{ value|lower }}

If ``value`` is ``Still MAD At Yoko``, the output will be
``still mad at yoko``.

.. templatefilter:: make_list

make_list
^^^^^^^^^

Returns the value turned into a list. For a string, it's a list of characters.
For an integer, the argument is cast into an unicode string before creating a
list.

For example::

    {{ value|make_list }}

If ``value`` is the string ``"Joel"``, the output would be the list
``[u'J', u'o', u'e', u'l']``. If ``value`` is ``123``, the output will be the
list ``[u'1', u'2', u'3']``.

.. templatefilter:: phone2numeric

phone2numeric
^^^^^^^^^^^^^

Converts a phone number (possibly containing letters) to its numerical
equivalent.

The input doesn't have to be a valid phone number. This will happily convert
any string.

For example::

    {{ value|phone2numeric }}

If ``value`` is ``800-COLLECT``, the output will be ``800-2655328``.

.. templatefilter:: pluralize

pluralize
^^^^^^^^^

Returns a plural suffix if the value is not 1. By default, this suffix is
``'s'``.

Example::

    You have {{ num_messages }} message{{ num_messages|pluralize }}.

If ``num_messages`` is ``1``, the output will be ``You have 1 message.``
If ``num_messages`` is ``2``  the output will be ``You have 2 messages.``

For words that require a suffix other than ``'s'``, you can provide an alternate
suffix as a parameter to the filter.

Example::

    You have {{ num_walruses }} walrus{{ num_walruses|pluralize:"es" }}.

For words that don't pluralize by simple suffix, you can specify both a
singular and plural suffix, separated by a comma.

Example::

    You have {{ num_cherries }} cherr{{ num_cherries|pluralize:"y,ies" }}.

.. note:: Use :ttag:`blocktrans` to pluralize translated strings.

.. templatefilter:: pprint

pprint
^^^^^^

A wrapper around :func:`pprint.pprint` -- for debugging, really.

.. templatefilter:: random

random
^^^^^^

Returns a random item from the given list.

For example::

    {{ value|random }}

If ``value`` is the list ``['a', 'b', 'c', 'd']``, the output could be ``"b"``.

.. templatefilter:: removetags

removetags
^^^^^^^^^^

Removes a space-separated list of [X]HTML tags from the output.

For example::

    {{ value|removetags:"b span"|safe }}

If ``value`` is ``"<b>Joel</b> <button>is</button> a <span>slug</span>"`` the
output will be ``"Joel <button>is</button> a slug"``.

Note that this filter is case-sensitive.

If ``value`` is ``"<B>Joel</B> <button>is</button> a <span>slug</span>"`` the
output will be ``"<B>Joel</B> <button>is</button> a slug"``.

.. templatefilter:: rjust

rjust
^^^^^

Right-aligns the value in a field of a given width.

**Argument:** field size

For example::

    "{{ value|rjust:"10" }}"

If ``value`` is ``Django``, the output will be ``"    Django"``.

.. templatefilter:: safe

safe
^^^^

Marks a string as not requiring further HTML escaping prior to output. When
autoescaping is off, this filter has no effect.

.. note::

    If you are chaining filters, a filter applied after ``safe`` can
    make the contents unsafe again. For example, the following code
    prints the variable as is, unescaped:

    .. code-block:: html+django

        {{ var|safe|escape }}

.. templatefilter:: safeseq

safeseq
^^^^^^^

Applies the :tfilter:`safe` filter to each element of a sequence.  Useful in
conjunction with other filters that operate on sequences, such as
:tfilter:`join`.  For example::

    {{ some_list|safeseq|join:", " }}

You couldn't use the :tfilter:`safe` filter directly in this case, as it would
first convert the variable into a string, rather than working with the
individual elements of the sequence.

.. templatefilter:: slice

slice
^^^^^

Returns a slice of the list.

Uses the same syntax as Python's list slicing. See
http://diveintopython.net/native_data_types/lists.html#odbchelper.list.slice
for an introduction.

Example::

    {{ some_list|slice:":2" }}

If ``some_list`` is ``['a', 'b', 'c']``, the output will be ``['a', 'b']``.

.. templatefilter:: slugify

slugify
^^^^^^^

Converts to lowercase, removes non-word characters (alphanumerics and
underscores) and converts spaces to hyphens. Also strips leading and trailing
whitespace.

For example::

    {{ value|slugify }}

If ``value`` is ``"Joel is a slug"``, the output will be ``"joel-is-a-slug"``.

.. templatefilter:: stringformat

stringformat
^^^^^^^^^^^^

Formats the variable according to the argument, a string formatting specifier.
This specifier uses Python string formatting syntax, with the exception that
the leading "%" is dropped.

See http://docs.python.org/library/stdtypes.html#string-formatting-operations
for documentation of Python string formatting

For example::

    {{ value|stringformat:"s" }}

If ``value`` is ``"Joel is a slug"``, the output will be ``"Joel is a slug"``.

.. templatefilter:: striptags

striptags
^^^^^^^^^

Strips all [X]HTML tags.

For example::

    {{ value|striptags }}

If ``value`` is ``"<b>Joel</b> <button>is</button> a <span>slug</span>"``, the
output will be ``"Joel is a slug"``.

.. templatefilter:: time

time
^^^^

Formats a time according to the given format.

Given format can be the predefined one :setting:`TIME_FORMAT`, or a custom
format, same as the :tfilter:`date` filter. Note that the predefined format
is locale-dependant.

The time filter will only accept parameters in the format string that relate
to the time of day, not the date (for obvious reasons). If you need to
format a date, use the :tfilter:`date` filter.

For example::

    {{ value|time:"H:i" }}

If ``value`` is equivalent to ``datetime.datetime.now()``, the output will be
the string ``"01:23"``.

Another example:

Assuming that :setting:`USE_L10N` is ``True`` and :setting:`LANGUAGE_CODE` is,
for example, ``"de"``, then for::

    {{ value|time:"TIME_FORMAT" }}

the output will be the string ``"01:23:00"`` (The ``"TIME_FORMAT"`` format
specifier for the ``de`` locale as shipped with Django is ``"H:i:s"``).

When used without a format string::

    {{ value|time }}

...the formatting string defined in the :setting:`TIME_FORMAT` setting will be
used, without applying any localization.

.. versionchanged:: 1.2
    Predefined formats can now be influenced by the current locale.

.. templatefilter:: timesince

timesince
^^^^^^^^^

Formats a date as the time since that date (e.g., "4 days, 6 hours").

Takes an optional argument that is a variable containing the date to use as
the comparison point (without the argument, the comparison point is *now*).
For example, if ``blog_date`` is a date instance representing midnight on 1
June 2006, and ``comment_date`` is a date instance for 08:00 on 1 June 2006,
then ``{{ blog_date|timesince:comment_date }}`` would return "8 hours".

Comparing offset-naive and offset-aware datetimes will return an empty string.

Minutes is the smallest unit used, and "0 minutes" will be returned for any
date that is in the future relative to the comparison point.

.. templatefilter:: timeuntil

timeuntil
^^^^^^^^^

Similar to ``timesince``, except that it measures the time from now until the
given date or datetime. For example, if today is 1 June 2006 and
``conference_date`` is a date instance holding 29 June 2006, then
``{{ conference_date|timeuntil }}`` will return "4 weeks".

Takes an optional argument that is a variable containing the date to use as
the comparison point (instead of *now*). If ``from_date`` contains 22 June
2006, then ``{{ conference_date|timeuntil:from_date }}`` will return "1 week".

Comparing offset-naive and offset-aware datetimes will return an empty string.

Minutes is the smallest unit used, and "0 minutes" will be returned for any
date that is in the past relative to the comparison point.

.. templatefilter:: title

title
^^^^^

Converts a string into titlecase.

For example::

    {{ value|title }}

If ``value`` is ``"my first post"``, the output will be ``"My First Post"``.

.. templatefilter:: truncatechars

truncatechars
^^^^^^^^^^^^^

.. versionadded:: 1.4

Truncates a string if it is longer than the specified number of characters.
Truncated strings will end with a translatable ellipsis sequence ("...").

**Argument:** Number of characters to truncate to

For example::

    {{ value|truncatechars:9 }}

If ``value`` is ``"Joel is a slug"``, the output will be ``"Joel i..."``.

.. templatefilter:: truncatewords

truncatewords
^^^^^^^^^^^^^

Truncates a string after a certain number of words.

**Argument:** Number of words to truncate after

For example::

    {{ value|truncatewords:2 }}

If ``value`` is ``"Joel is a slug"``, the output will be ``"Joel is ..."``.

Newlines within the string will be removed.

.. templatefilter:: truncatewords_html

truncatewords_html
^^^^^^^^^^^^^^^^^^

Similar to :tfilter:`truncatewords`, except that it is aware of HTML tags. Any
tags that are opened in the string and not closed before the truncation point,
are closed immediately after the truncation.

This is less efficient than :tfilter:`truncatewords`, so should only be used
when it is being passed HTML text.

For example::

    {{ value|truncatewords_html:2 }}

If ``value`` is ``"<p>Joel is a slug</p>"``, the output will be
``"<p>Joel is ...</p>"``.

Newlines in the HTML content will be preserved.

.. templatefilter:: unordered_list

unordered_list
^^^^^^^^^^^^^^

Recursively takes a self-nested list and returns an HTML unordered list --
WITHOUT opening and closing <ul> tags.

The list is assumed to be in the proper format. For example, if ``var``
contains ``['States', ['Kansas', ['Lawrence', 'Topeka'], 'Illinois']]``, then
``{{ var|unordered_list }}`` would return::

    <li>States
    <ul>
            <li>Kansas
            <ul>
                    <li>Lawrence</li>
                    <li>Topeka</li>
            </ul>
            </li>
            <li>Illinois</li>
    </ul>
    </li>

Note: An older, more restrictive and verbose input format is also supported:
``['States', [['Kansas', [['Lawrence', []], ['Topeka', []]]], ['Illinois', []]]]``,

.. templatefilter:: upper

upper
^^^^^

Converts a string into all uppercase.

For example::

    {{ value|upper }}

If ``value`` is ``"Joel is a slug"``, the output will be ``"JOEL IS A SLUG"``.

.. templatefilter:: urlencode

urlencode
^^^^^^^^^

Escapes a value for use in a URL.

For example::

    {{ value|urlencode }}

If ``value`` is ``"http://www.example.org/foo?a=b&c=d"``, the output will be
``"http%3A//www.example.org/foo%3Fa%3Db%26c%3Dd"``.

.. versionadded:: 1.3

An optional argument containing the characters which should not be escaped can
be provided.

If not provided, the '/' character is assumed safe. An empty string can be
provided when *all* characters should be escaped. For example::

    {{ value|urlencode:"" }}

If ``value`` is ``"http://www.example.org/"``, the output will be
``"http%3A%2F%2Fwww.example.org%2F"``.

.. templatefilter:: urlize

urlize
^^^^^^

Converts URLs in text into clickable links.

This template tag works on links prefixed with ``http://``, ``https://``, or
``www.``. For example, ``http://goo.gl/aia1t`` will get converted but
``goo.gl/aia1t`` won't.

It also supports domain-only links ending in one of the original top level
domains (``.com``, ``.edu``, ``.gov``, ``.int``, ``.mil``, ``.net``, and
``.org``). For example, ``djangoproject.com`` gets converted.

.. versionchanged:: 1.4

Until Django 1.4, only the ``.com``, ``.net`` and ``.org`` suffixes were
supported for domain-only links.

Links can have trailing punctuation (periods, commas, close-parens) and leading
punctuation (opening parens), and ``urlize`` will still do the right thing.

Links generated by ``urlize`` have a ``rel="nofollow"`` attribute added
to them.

For example::

    {{ value|urlize }}

If ``value`` is ``"Check out www.djangoproject.com"``, the output will be
``"Check out <a href="http://www.djangoproject.com"
rel="nofollow">www.djangoproject.com</a>"``.

The ``urlize`` filter also takes an optional parameter ``autoescape``. If
``autoescape`` is ``True``, the link text and URLs will be escaped using
Django's built-in :tfilter:`escape` filter. The default value for
``autoescape`` is ``True``.

.. note::

    If ``urlize`` is applied to text that already contains HTML markup,
    things won't work as expected. Apply this filter only to plain text.

.. templatefilter:: urlizetrunc

urlizetrunc
^^^^^^^^^^^

Converts URLs into clickable links just like urlize_, but truncates URLs
longer than the given character limit.

**Argument:** Number of characters that link text should be truncated to,
including the ellipsis that's added if truncation is necessary.

For example::

    {{ value|urlizetrunc:15 }}

If ``value`` is ``"Check out www.djangoproject.com"``, the output would be
``'Check out <a href="http://www.djangoproject.com"
rel="nofollow">www.djangopr...</a>'``.

As with urlize_, this filter should only be applied to plain text.

.. templatefilter:: wordcount

wordcount
^^^^^^^^^

Returns the number of words.

For example::

    {{ value|wordcount }}

If ``value`` is ``"Joel is a slug"``, the output will be ``4``.

.. templatefilter:: wordwrap

wordwrap
^^^^^^^^

Wraps words at specified line length.

**Argument:** number of characters at which to wrap the text

For example::

    {{ value|wordwrap:5 }}

If ``value`` is ``Joel is a slug``, the output would be::

    Joel
    is a
    slug

.. templatefilter:: yesno

yesno
^^^^^

Maps values for true, false and (optionally) None, to the strings "yes", "no",
"maybe", or a custom mapping passed as a comma-separated list, and
returns one of those strings according to the value:

For example::

    {{ value|yesno:"yeah,no,maybe" }}

==========  ======================  ==================================
Value       Argument                Outputs
==========  ======================  ==================================
``True``                            ``yes``
``True``    ``"yeah,no,maybe"``     ``yeah``
``False``   ``"yeah,no,maybe"``     ``no``
``None``    ``"yeah,no,maybe"``     ``maybe``
``None``    ``"yeah,no"``           ``"no"`` (converts None to False
                                    if no mapping for None is given)
==========  ======================  ==================================

Internationalization tags and filters
-------------------------------------

Django provides template tags and filters to control each aspect of
:doc:`internationalization </topics/i18n/index>` in templates. They allow for
granular control of translations, formatting, and time zone conversions.

i18n
^^^^

This library allows specifying translatable text in templates.
To enable it, set :setting:`USE_I18N` to ``True``, then load it with
``{% load i18n %}``.

See :ref:`specifying-translation-strings-in-template-code`.

l10n
^^^^

This library provides control over the localization of values in templates.
You only need to load the library using ``{% load l10n %}``, but you'll often
set :setting:`USE_L10N` to ``True`` so that localization is active by default.

See :ref:`topic-l10n-templates`.

tz
^^

.. versionadded:: 1.4

This library provides control over time zone conversions in templates.
Like ``l10n``, you only need to load the library using ``{% load tz %}``,
but you'll usually also set :setting:`USE_TZ` to ``True`` so that conversion
to local time happens by default.

See :ref:`time-zones-in-templates`.

Other tags and filters libraries
--------------------------------

Django comes with a couple of other template-tag libraries that you have to
enable explicitly in your :setting:`INSTALLED_APPS` setting and enable in your
template with the :ttag:`{% load %}<load>` tag.

django.contrib.humanize
^^^^^^^^^^^^^^^^^^^^^^^

A set of Django template filters useful for adding a "human touch" to data. See
:doc:`/ref/contrib/humanize`.

django.contrib.markup
^^^^^^^^^^^^^^^^^^^^^

A collection of template filters that implement these common markup languages:

* Textile
* Markdown
* reST (reStructuredText)

See the :doc:`markup documentation </ref/contrib/markup>`.

django.contrib.webdesign
^^^^^^^^^^^^^^^^^^^^^^^^

A collection of template tags that can be useful while designing a Web site,
such as a generator of Lorem Ipsum text. See :doc:`/ref/contrib/webdesign`.

static
^^^^^^

.. templatetag:: static

static
""""""

.. highlight:: html+django

To link to static files that are saved in :setting:`STATIC_ROOT` Django ships
with a :ttag:`static` template tag. You can use this regardless if you're
using :class:`~django.template.RequestContext` or not.

.. code-block:: html+django

    {% load static %}
    <img src="{% static "images/hi.jpg" %}" />

It is also able to consume standard context variables, e.g. assuming a
``user_stylesheet`` variable is passed to the template:

.. code-block:: html+django

    {% load static %}
    <link rel="stylesheet" href="{% static user_stylesheet %}" type="text/css" media="screen" />

.. note::

    The :mod:`staticfiles<django.contrib.staticfiles>` contrib app also ships
    with a :ttag:`static template tag<staticfiles-static>` which uses
    ``staticfiles'`` :setting:`STATICFILES_STORAGE` to build the URL of the
    given path. Use that instead if you have an advanced use case such as
    :ref:`using a cloud service to serve static files<staticfiles-from-cdn>`::

        {% load static from staticfiles %}
        <img src="{% static "images/hi.jpg" %}" />

.. templatetag:: get_static_prefix

get_static_prefix
"""""""""""""""""

.. highlight:: html+django

If you're not using :class:`~django.template.RequestContext`, or if you need
more control over exactly where and how :setting:`STATIC_URL` is injected
into the template, you can use the :ttag:`get_static_prefix` template tag
instead::

    {% load static %}
    <img src="{% get_static_prefix %}images/hi.jpg" />

There's also a second form you can use to avoid extra processing if you need
the value multiple times::

    {% load static %}
    {% get_static_prefix as STATIC_PREFIX %}

    <img src="{{ STATIC_PREFIX }}images/hi.jpg" />
    <img src="{{ STATIC_PREFIX }}images/hi2.jpg" />

.. templatetag:: get_media_prefix

get_media_prefix
""""""""""""""""

.. highlight:: html+django

Similar to the :ttag:`get_static_prefix`, ``get_media_prefix`` populates a
template variable with the media prefix :setting:`MEDIA_URL`, e.g.::

    <script type="text/javascript" charset="utf-8">
    var media_path = '{% get_media_prefix %}';
    </script>