表单组是可以在同一个页面上放置多个表单。就好比DataGrid那样。来看看下面这个表单:
>>> from django import forms
>>> class ArticleForm(forms.Form):
... title = forms.CharField()
... pub_date = forms.DateField()
你可能会希望用户同时创建多个articles。创建一个``ArticleForm``表单组，你可以这样做:
>>> from django.forms.formsets import formset_factory
>>> ArticleFormSet = formset_factory(ArticleForm)
现在，你就构建了一个名称为``ArticleFormSet``的表单组。表单组让你可以在表单里重复呈现相同规律的 表单:
>>> formset = ArticleFormSet()
>>> for form in formset:
... print form.as_table()
<tr><th><label for="id_form-0-title">Title:</label></th><td><input type="text" name="form-0-title" id="id_form-0-title" /></td></tr>
<tr><th><label for="id_form-0-pub_date">Pub date:</label></th><td><input type="text" name="form-0-pub_date" id="id_form-0-pub_date" /></td></tr>
上面只呈现了一个空表表单。可以通过``extra``参数来控制呈现的空白表单的数量。默认情况下， ``formset_factory``只定义一个额外表单。下面的例子会呈现两个:
>>> ArticleFormSet = formset_factory(ArticleForm, extra=2)
在Django 1.3里，表单组不能被循环。要呈现表单组，你需要循环``forms``属性:
>>> formset = ArticleFormSet()
>>> for form in formset.forms:
... print form.as_table()
循环的``formset.forms``会按顺序呈现表单。默认表单组迭代器也会按这样的顺序呈现， 但你可以通过重写:meth:`__iter__()`方法来改变这个顺序。
表单组也可被索引，它会返回相应的表单。在重写``__iter__``时，你也需要重写``__getitem__`` 来提供匹配行为。
初始化参数会给予表单组主要能力。就像上面那样，你可以定义呈现多少个表单。这意味着初始化参数告诉 表单组需要呈现多少个表单。来看看下面的例子:
>>> ArticleFormSet = formset_factory(ArticleForm, extra=2)
>>> formset = ArticleFormSet(initial=[
... {'title': u'Django is now open source',
... 'pub_date': datetime.date.today(),}
... ])
>>> for form in formset:
... print form.as_table()
<tr><th><label for="id_form-0-title">Title:</label></th><td><input type="text" name="form-0-title" value="Django is now open source" id="id_form-0-title" /></td></tr>
<tr><th><label for="id_form-0-pub_date">Pub date:</label></th><td><input type="text" name="form-0-pub_date" value="2008-05-12" id="id_form-0-pub_date" /></td></tr>
<tr><th><label for="id_form-1-title">Title:</label></th><td><input type="text" name="form-1-title" id="id_form-1-title" /></td></tr>
<tr><th><label for="id_form-1-pub_date">Pub date:</label></th><td><input type="text" name="form-1-pub_date" id="id_form-1-pub_date" /></td></tr>
<tr><th><label for="id_form-2-title">Title:</label></th><td><input type="text" name="form-2-title" id="id_form-2-title" /></td></tr>
<tr><th><label for="id_form-2-pub_date">Pub date:</label></th><td><input type="text" name="form-2-pub_date" id="id_form-2-pub_date" /></td></tr>
上面一共有三个表单。其中一个初始化参数传入了2个额外表单。同时注意到我们也传入了一个字典列表作为 初始化参数。
``formset_factory``的``max_num``参数让你可以控制会有多少个空白表单生成:
>>> ArticleFormSet = formset_factory(ArticleForm, extra=2, max_num=1)
>>> formset = ArticleFormset()
>>> for form in formset:
... print form.as_table()
<tr><th><label for="id_form-0-title">Title:</label></th><td><input type="text" name="form-0-title" id="id_form-0-title" /></td></tr>
<tr><th><label for="id_form-0-pub_date">Pub date:</label></th><td><input type="text" name="form-0-pub_date" id="id_form-0-pub_date" /></td></tr>
如果``max_num``的值大于已存在对象的数量，``extra``个额外表单将添加到表单组中，只要不 超过``max_num``的数量。
如果设置``max_num``的值为``None``（这也是默认值），那么生成的表单数量将是无限个。要 注意在1.2版里，``max_num``的默认值从0改成了``None``，在1.2版里，``0``是有效值。
验证表单基本和``表单``几乎一致。表单组里的``is_valid``方法提供了一种从表单组里验证表单的功能:
>>> ArticleFormSet = formset_factory(ArticleForm)
>>> data = {
... 'form-TOTAL_FORMS': u'1',
... 'form-INITIAL_FORMS': u'0',
... 'form-MAX_NUM_FORMS': u'',
... }
>>> formset = ArticleFormSet(data)
>>> formset.is_valid()
True
我们在一个表单中不输入任何东西。表单组将只能忽略我们没作变更的额外表单。但如果我们输入 了无效的article:
>>> data = {
... 'form-TOTAL_FORMS': u'2',
... 'form-INITIAL_FORMS': u'0',
... 'form-MAX_NUM_FORMS': u'',
... 'form-0-title': u'Test',
... 'form-0-pub_date': u'1904-06-16',
... 'form-1-title': u'Test',
... 'form-1-pub_date': u'', # <-- this date is missing but required
... }
>>> formset = ArticleFormSet(data)
>>> formset.is_valid()
False
>>> formset.errors
[{}, {'pub_date': [u'This field is required.']}]
就上上面那样，``formset.errors``是整个表单组所对应的错误列表。两个表单都经过验证， 而且错误消息出现在了第二个列表里。
我们也可以看看表单数据是否和初始值是否一样（假如表单没有发来任何数据）:
>>> data = {
... 'form-TOTAL_FORMS': u'1',
... 'form-INITIAL_FORMS': u'0',
... 'form-MAX_NUM_FORMS': u'',
... 'form-0-title': u'',
... 'form-0-pub_date': u'',
... }
>>> formset = ArticleFormSet(data)
>>> formset.has_changed()
False
你可能注意到了一些额外的值（``form-TOTAL_FORMS``， ``form-INITIAL_FORMS``及``form-MAX_NUM_FORMS``）这都是表单组所需要 的数据。这些都是``ManagementForm``所必须的。这种是用于管理表单组的方式。 如果你不提供这些管理数据，将会报错:
>>> data = {
... 'form-0-title': u'Test',
... 'form-0-pub_date': u'',
... }
>>> formset = ArticleFormSet(data)
Traceback (most recent call last):
...
django.forms.util.ValidationError: [u'ManagementForm data is missing or has been tampered with']
这是用来跟踪有多少表单对象呈现用的。如果你使用JavaScript来添加新表单，那么就应该在表单里 添加这个字段的值。
The management form is available as an attribute of the formset itself. When rendering a formset in a template, you can include all the management data by rendering {{ my_formset.management_form }} (substituting the name of your formset as appropriate).
BaseFormSet has a couple of methods that are closely related to the ManagementForm, total_form_count and initial_form_count.
total_form_count returns the total number of forms in this formset. initial_form_count returns the number of forms in the formset that were pre-filled, and is also used to determine how many forms are required. You will probably never need to override either of these methods, so please be sure you understand what they do before doing so.
BaseFormSet provides an additional attribute empty_form which returns a form instance with a prefix of __prefix__ for easier use in dynamic forms with JavaScript.
A formset has a clean method similar to the one on a Form class. This is where you define your own validation that works at the formset level:
>>> from django.forms.formsets import BaseFormSet
>>> class BaseArticleFormSet(BaseFormSet):
... def clean(self):
... """Checks that no two articles have the same title."""
... if any(self.errors):
... # Don't bother validating the formset unless each form is valid on its own
... return
... titles = []
... for i in range(0, self.total_form_count()):
... form = self.forms[i]
... title = form.cleaned_data['title']
... if title in titles:
... raise forms.ValidationError("Articles in a set must have distinct titles.")
... titles.append(title)
>>> ArticleFormSet = formset_factory(ArticleForm, formset=BaseArticleFormSet)
>>> data = {
... 'form-TOTAL_FORMS': u'2',
... 'form-INITIAL_FORMS': u'0',
... 'form-MAX_NUM_FORMS': u'',
... 'form-0-title': u'Test',
... 'form-0-pub_date': u'1904-06-16',
... 'form-1-title': u'Test',
... 'form-1-pub_date': u'1912-06-23',
... }
>>> formset = ArticleFormSet(data)
>>> formset.is_valid()
False
>>> formset.errors
[{}, {}]
>>> formset.non_form_errors()
[u'Articles in a set must have distinct titles.']
The formset clean method is called after all the Form.clean methods have been called. The errors will be found using the non_form_errors() method on the formset.
Common use cases with a formset is dealing with ordering and deletion of the form instances. This has been dealt with for you. The formset_factory provides two optional parameters can_order and can_delete that will do the extra work of adding the extra fields and providing simpler ways of getting to that data.
Default: False
Lets you create a formset with the ability to order:
>>> ArticleFormSet = formset_factory(ArticleForm, can_order=True)
>>> formset = ArticleFormSet(initial=[
... {'title': u'Article #1', 'pub_date': datetime.date(2008, 5, 10)},
... {'title': u'Article #2', 'pub_date': datetime.date(2008, 5, 11)},
... ])
>>> for form in formset:
... print form.as_table()
<tr><th><label for="id_form-0-title">Title:</label></th><td><input type="text" name="form-0-title" value="Article #1" id="id_form-0-title" /></td></tr>
<tr><th><label for="id_form-0-pub_date">Pub date:</label></th><td><input type="text" name="form-0-pub_date" value="2008-05-10" id="id_form-0-pub_date" /></td></tr>
<tr><th><label for="id_form-0-ORDER">Order:</label></th><td><input type="text" name="form-0-ORDER" value="1" id="id_form-0-ORDER" /></td></tr>
<tr><th><label for="id_form-1-title">Title:</label></th><td><input type="text" name="form-1-title" value="Article #2" id="id_form-1-title" /></td></tr>
<tr><th><label for="id_form-1-pub_date">Pub date:</label></th><td><input type="text" name="form-1-pub_date" value="2008-05-11" id="id_form-1-pub_date" /></td></tr>
<tr><th><label for="id_form-1-ORDER">Order:</label></th><td><input type="text" name="form-1-ORDER" value="2" id="id_form-1-ORDER" /></td></tr>
<tr><th><label for="id_form-2-title">Title:</label></th><td><input type="text" name="form-2-title" id="id_form-2-title" /></td></tr>
<tr><th><label for="id_form-2-pub_date">Pub date:</label></th><td><input type="text" name="form-2-pub_date" id="id_form-2-pub_date" /></td></tr>
<tr><th><label for="id_form-2-ORDER">Order:</label></th><td><input type="text" name="form-2-ORDER" id="id_form-2-ORDER" /></td></tr>
This adds an additional field to each form. This new field is named ORDER and is an forms.IntegerField. For the forms that came from the initial data it automatically assigned them a numeric value. Let’s look at what will happen when the user changes these values:
>>> data = {
... 'form-TOTAL_FORMS': u'3',
... 'form-INITIAL_FORMS': u'2',
... 'form-MAX_NUM_FORMS': u'',
... 'form-0-title': u'Article #1',
... 'form-0-pub_date': u'2008-05-10',
... 'form-0-ORDER': u'2',
... 'form-1-title': u'Article #2',
... 'form-1-pub_date': u'2008-05-11',
... 'form-1-ORDER': u'1',
... 'form-2-title': u'Article #3',
... 'form-2-pub_date': u'2008-05-01',
... 'form-2-ORDER': u'0',
... }
>>> formset = ArticleFormSet(data, initial=[
... {'title': u'Article #1', 'pub_date': datetime.date(2008, 5, 10)},
... {'title': u'Article #2', 'pub_date': datetime.date(2008, 5, 11)},
... ])
>>> formset.is_valid()
True
>>> for form in formset.ordered_forms:
... print form.cleaned_data
{'pub_date': datetime.date(2008, 5, 1), 'ORDER': 0, 'title': u'Article #3'}
{'pub_date': datetime.date(2008, 5, 11), 'ORDER': 1, 'title': u'Article #2'}
{'pub_date': datetime.date(2008, 5, 10), 'ORDER': 2, 'title': u'Article #1'}
Default: False
Lets you create a formset with the ability to delete:
>>> ArticleFormSet = formset_factory(ArticleForm, can_delete=True)
>>> formset = ArticleFormSet(initial=[
... {'title': u'Article #1', 'pub_date': datetime.date(2008, 5, 10)},
... {'title': u'Article #2', 'pub_date': datetime.date(2008, 5, 11)},
... ])
>>> for form in formset:
.... print form.as_table()
<input type="hidden" name="form-TOTAL_FORMS" value="3" id="id_form-TOTAL_FORMS" /><input type="hidden" name="form-INITIAL_FORMS" value="2" id="id_form-INITIAL_FORMS" /><input type="hidden" name="form-MAX_NUM_FORMS" id="id_form-MAX_NUM_FORMS" />
<tr><th><label for="id_form-0-title">Title:</label></th><td><input type="text" name="form-0-title" value="Article #1" id="id_form-0-title" /></td></tr>
<tr><th><label for="id_form-0-pub_date">Pub date:</label></th><td><input type="text" name="form-0-pub_date" value="2008-05-10" id="id_form-0-pub_date" /></td></tr>
<tr><th><label for="id_form-0-DELETE">Delete:</label></th><td><input type="checkbox" name="form-0-DELETE" id="id_form-0-DELETE" /></td></tr>
<tr><th><label for="id_form-1-title">Title:</label></th><td><input type="text" name="form-1-title" value="Article #2" id="id_form-1-title" /></td></tr>
<tr><th><label for="id_form-1-pub_date">Pub date:</label></th><td><input type="text" name="form-1-pub_date" value="2008-05-11" id="id_form-1-pub_date" /></td></tr>
<tr><th><label for="id_form-1-DELETE">Delete:</label></th><td><input type="checkbox" name="form-1-DELETE" id="id_form-1-DELETE" /></td></tr>
<tr><th><label for="id_form-2-title">Title:</label></th><td><input type="text" name="form-2-title" id="id_form-2-title" /></td></tr>
<tr><th><label for="id_form-2-pub_date">Pub date:</label></th><td><input type="text" name="form-2-pub_date" id="id_form-2-pub_date" /></td></tr>
<tr><th><label for="id_form-2-DELETE">Delete:</label></th><td><input type="checkbox" name="form-2-DELETE" id="id_form-2-DELETE" /></td></tr>
Similar to can_order this adds a new field to each form named DELETE and is a forms.BooleanField. When data comes through marking any of the delete fields you can access them with deleted_forms:
>>> data = {
... 'form-TOTAL_FORMS': u'3',
... 'form-INITIAL_FORMS': u'2',
... 'form-MAX_NUM_FORMS': u'',
... 'form-0-title': u'Article #1',
... 'form-0-pub_date': u'2008-05-10',
... 'form-0-DELETE': u'on',
... 'form-1-title': u'Article #2',
... 'form-1-pub_date': u'2008-05-11',
... 'form-1-DELETE': u'',
... 'form-2-title': u'',
... 'form-2-pub_date': u'',
... 'form-2-DELETE': u'',
... }
>>> formset = ArticleFormSet(data, initial=[
... {'title': u'Article #1', 'pub_date': datetime.date(2008, 5, 10)},
... {'title': u'Article #2', 'pub_date': datetime.date(2008, 5, 11)},
... ])
>>> [form.cleaned_data for form in formset.deleted_forms]
[{'DELETE': True, 'pub_date': datetime.date(2008, 5, 10), 'title': u'Article #1'}]
If you need to add additional fields to the formset this can be easily accomplished. The formset base class provides an add_fields method. You can simply override this method to add your own fields or even redefine the default fields/attributes of the order and deletion fields:
>>> class BaseArticleFormSet(BaseFormSet):
... def add_fields(self, form, index):
... super(BaseArticleFormSet, self).add_fields(form, index)
... form.fields["my_field"] = forms.CharField()
>>> ArticleFormSet = formset_factory(ArticleForm, formset=BaseArticleFormSet)
>>> formset = ArticleFormSet()
>>> for form in formset:
... print form.as_table()
<tr><th><label for="id_form-0-title">Title:</label></th><td><input type="text" name="form-0-title" id="id_form-0-title" /></td></tr>
<tr><th><label for="id_form-0-pub_date">Pub date:</label></th><td><input type="text" name="form-0-pub_date" id="id_form-0-pub_date" /></td></tr>
<tr><th><label for="id_form-0-my_field">My field:</label></th><td><input type="text" name="form-0-my_field" id="id_form-0-my_field" /></td></tr>
Using a formset inside a view is as easy as using a regular Form class. The only thing you will want to be aware of is making sure to use the management form inside the template. Let’s look at a sample view:
def manage_articles(request):
ArticleFormSet = formset_factory(ArticleForm)
if request.method == 'POST':
formset = ArticleFormSet(request.POST, request.FILES)
if formset.is_valid():
# do something with the formset.cleaned_data
pass
else:
formset = ArticleFormSet()
return render_to_response('manage_articles.html', {'formset': formset})
The manage_articles.html template might look like this:
<form method="post" action="">
{{ formset.management_form }}
<table>
{% for form in formset %}
{{ form }}
{% endfor %}
</table>
</form>
However the above can be slightly shortcutted and let the formset itself deal with the management form:
<form method="post" action="">
<table>
{{ formset }}
</table>
</form>
The above ends up calling the as_table method on the formset class.
If you manually render fields in the template, you can render can_delete parameter with {{ form.DELETE }}:
<form method="post" action="">
{{ formset.management_form }}
{% for form in formset %}
{{ form.id }}
<ul>
<li>{{ form.title }}</li>
{% if formset.can_delete %}
<li>{{ form.DELETE }}</li>
{% endif %}
</ul>
{% endfor %}
</form>
Similarly, if the formset has the ability to order (can_order=True), it is possible to render it with {{ form.ORDER }}.
You are able to use more than one formset in a view if you like. Formsets borrow much of its behavior from forms. With that said you are able to use prefix to prefix formset form field names with a given value to allow more than one formset to be sent to a view without name clashing. Lets take a look at how this might be accomplished:
def manage_articles(request):
ArticleFormSet = formset_factory(ArticleForm)
BookFormSet = formset_factory(BookForm)
if request.method == 'POST':
article_formset = ArticleFormSet(request.POST, request.FILES, prefix='articles')
book_formset = BookFormSet(request.POST, request.FILES, prefix='books')
if article_formset.is_valid() and book_formset.is_valid():
# do something with the cleaned_data on the formsets.
pass
else:
article_formset = ArticleFormSet(prefix='articles')
book_formset = BookFormSet(prefix='books')
return render_to_response('manage_articles.html', {
'article_formset': article_formset,
'book_formset': book_formset,
})
You would then render the formsets as normal. It is important to point out that you need to pass prefix on both the POST and non-POST cases so that it is rendered and processed correctly.
Dec 14, 2013