フォームセット (Formsets)

class BaseFormSet[ソース]

フォームセットとは、同じページで複数のフォームを扱うための抽象化レイヤで、いわばデータグリッドのようなものです。フォームセットを説明するために、まず以下のようなフォームを考えましょう。

>>> from django import forms
>>> class ArticleForm(forms.Form):
...     title = forms.CharField()
...     pub_date = forms.DateField()

このフォームを使って、ユーザが一度に複数の記事を作成できるようにしたいとします。ArticleForm からフォームセットを生成するには、次のようにします。

>>> from django.forms import formset_factory
>>> ArticleFormSet = formset_factory(ArticleForm)

ArticleFormSet という名前のフォームセットができました。このフォー ムセットには、フォームセットに入っているフォームを一つ一つ取り出して、それぞれを普通のフォームとして表示する機能があります。

>>> 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>

出力を見て分かる通り、空のフォームが 1 つだけ表示されています。 今表示されている空っぽのフォームの合計数は、extra パラメータによってコントロールされます。formset_factory() のデフォルトの設定で、「追加のフォーム表示数 (extra)」 を 1 に設定しているからです。次の例は、2 つの空っぽのフォームを出します。

>>> ArticleFormSet = formset_factory(ArticleForm, extra=2)

formset をイテレートすると、フォームは作成された順番でレンダリングされます。この順番は、 __iter__() メソッドで代わりの実装をすることで変更できます。

フォームセットは、インデックスを入れこむこともできます。フォームセットは組み込まれたフォームを返します。もし、 __iter__ をオーバーライドしたならば、 __getitem__ も、フォームとのマッチングのためにオーバーライドする必要があります。

フォームセットに初期データを指定する

初期データは、フォームセットのユーザビリティに大きく影響します。上に示したように、 追加するフォームの数を指定できます。 この「追加」とは、初期データから生成されるフォームに加えて、追加で表示される空のフォーム数という意味です。以下の例を見てください:

>>> import datetime
>>> from django.forms import formset_factory
>>> from myapp.forms import ArticleForm
>>> ArticleFormSet = formset_factory(ArticleForm, extra=2)
>>> formset = ArticleFormSet(initial=[
...     {'title': '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>

上の例では、今度は 3 つのフォームが表示されました。初期データとして渡された 1 つと、2 つの追加フォームです。初期データとして、辞書のリストを渡していることにも注意してください。

フォームセットを描画するために initial を使う場合、フォームセットの送信を処理するときに同じ initial を渡して、どのフォームがユーザによって変更されたかをフォームセットが検出できるようにしてください。例えば、ArticleFormSet(request.POST, initial=[...]) のようになるでしょう。

フォームの最大表示数を制限する

formset_factory()max_num パラメータを指定すると、フォームセット中に表示されるフォームの最大数を制限できます。

>>> from django.forms import formset_factory
>>> from myapp.forms import ArticleForm
>>> 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>

もし、max_num の値が初期データ内に存在するオブジェクトの合計より大きい場合、 extra を上限として空のフォームがフォームセットに追加されます。 フォームの合計の長さは max_num を超えることはできません。例えば、extra=2max_num=2、そしてフォームセットが 1 つの initial 項目で初期化される場合、この初期項目のフォームと 1 つの空のフォームが表示されます。

初期データ内の項目数が max_num を超える場合、max_num の値に関わらず全ての初期データのフォームが表示され、追加フォームは 1 つも表示されません。例えば、extra=3max_num=1、そしてフォームセットが 2 つの初期項目で初期化される場合、2 つのフォームが初期データとともに表示されます。

max_num の値が None (デフォルト) だった場合、表示されるフォームの上限は大きな数になります (1000)。この数は、実際には制限がないと見なせるでしょう。

デフォルトでは、max_num はいくつのフォームが表示されるかだけに影響し、バリデーションには影響しません。validate_max=Trueformset_factory() に渡される場合は、max_num はバリデーションに影響します。validate_max をご覧ください。

フォームセットのバリデーション

フォームセットのバリデーションは、普通の Form とほぼ同じです。フォームセットにも is_valid メソッドがあり、フォームセット内の全てのフォームを簡単に検証できます。

>>> from django.forms import formset_factory
>>> from myapp.forms import ArticleForm
>>> ArticleFormSet = formset_factory(ArticleForm)
>>> data = {
...     'form-TOTAL_FORMS': '1',
...     'form-INITIAL_FORMS': '0',
...     'form-MAX_NUM_FORMS': '',
... }
>>> formset = ArticleFormSet(data)
>>> formset.is_valid()
True

この例では、フォームセットにデータを渡さなかったので、有効なフォームを返しています。フォームセットは賢くて、データの変更されなかったフォームを無視してくれます。不適切な記事を提供しようとすると、以下のようになります。

>>> data = {
...     'form-TOTAL_FORMS': '2',
...     'form-INITIAL_FORMS': '0',
...     'form-MAX_NUM_FORMS': '',
...     'form-0-title': 'Test',
...     'form-0-pub_date': '1904-06-16',
...     'form-1-title': 'Test',
...     'form-1-pub_date': '', # <-- this date is missing but required
... }
>>> formset = ArticleFormSet(data)
>>> formset.is_valid()
False
>>> formset.errors
[{}, {'pub_date': ['This field is required.']}]

見て分かるように、 formset.errors はリストで、 そのエントリーはフォームセット内のフォームと一致します。 バリデーションは、2 つのフォームそれぞれに働いて、2 つ目の項目にエラーメッセージが表示されています。

通常の Form を使うときとまったく同じように、フォームセットのフォーム内のそれぞれのフィールドは、ブラウザのバリデーションのための maxlength のような HTML 属性を含むことができます。ただし、フォームセットのフォームフィールドは、required 属性を含みません。これは、フォームを追加したり削除するときにバリデーションが正しく働かない可能性があるためです。

BaseFormSet.total_error_count()[ソース]

フォームセット内にいくつのエラーがあるかを確かめるためには、total_error_count メソッドが使えます。

>>> # Using the previous example
>>> formset.errors
[{}, {'pub_date': ['This field is required.']}]
>>> len(formset.errors)
2
>>> formset.total_error_count()
1

また、フォームに入力されたデータと初期データが異なっているかどうかもチェックできます (たとえば、フォームがデータなしで送信された場合など)。

>>> data = {
...     'form-TOTAL_FORMS': '1',
...     'form-INITIAL_FORMS': '0',
...     'form-MAX_NUM_FORMS': '',
...     'form-0-title': '',
...     'form-0-pub_date': '',
... }
>>> formset = ArticleFormSet(data)
>>> formset.has_changed()
False

ManagementForm を理解する

You may have noticed the additional data (form-TOTAL_FORMS, form-INITIAL_FORMS and form-MAX_NUM_FORMS) that was required in the formset's data above. This data is required for the ManagementForm. This form is used by the formset to manage the collection of forms contained in the formset. If you don't provide this management data, an exception will be raised:

>>> data = {
...     'form-0-title': 'Test',
...     'form-0-pub_date': '',
... }
>>> formset = ArticleFormSet(data)
>>> formset.is_valid()
Traceback (most recent call last):
...
django.forms.utils.ValidationError: ['ManagementForm data is missing or has been tampered with']

It is used to keep track of how many form instances are being displayed. If you are adding new forms via JavaScript, you should increment the count fields in this form as well. On the other hand, if you are using JavaScript to allow deletion of existing objects, then you need to ensure the ones being removed are properly marked for deletion by including form-#-DELETE in the POST data. It is expected that all forms are present in the POST data regardless.

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).

total_form_count and initial_form_count

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.

empty_form

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.

Custom formset validation

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 import BaseFormSet
>>> from django.forms import formset_factory
>>> from myapp.forms import ArticleForm

>>> 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 form in self.forms:
...             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': '2',
...     'form-INITIAL_FORMS': '0',
...     'form-MAX_NUM_FORMS': '',
...     'form-0-title': 'Test',
...     'form-0-pub_date': '1904-06-16',
...     'form-1-title': 'Test',
...     'form-1-pub_date': '1912-06-23',
... }
>>> formset = ArticleFormSet(data)
>>> formset.is_valid()
False
>>> formset.errors
[{}, {}]
>>> formset.non_form_errors()
['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.

Validating the number of forms in a formset

Django provides a couple ways to validate the minimum or maximum number of submitted forms. Applications which need more customizable validation of the number of forms should use custom formset validation.

validate_max

If validate_max=True is passed to formset_factory(), validation will also check that the number of forms in the data set, minus those marked for deletion, is less than or equal to max_num.

>>> from django.forms import formset_factory
>>> from myapp.forms import ArticleForm
>>> ArticleFormSet = formset_factory(ArticleForm, max_num=1, validate_max=True)
>>> data = {
...     'form-TOTAL_FORMS': '2',
...     'form-INITIAL_FORMS': '0',
...     'form-MIN_NUM_FORMS': '',
...     'form-MAX_NUM_FORMS': '',
...     'form-0-title': 'Test',
...     'form-0-pub_date': '1904-06-16',
...     'form-1-title': 'Test 2',
...     'form-1-pub_date': '1912-06-23',
... }
>>> formset = ArticleFormSet(data)
>>> formset.is_valid()
False
>>> formset.errors
[{}, {}]
>>> formset.non_form_errors()
['Please submit 1 or fewer forms.']

validate_max=True validates against max_num strictly even if max_num was exceeded because the amount of initial data supplied was excessive.

注釈

Regardless of validate_max, if the number of forms in a data set exceeds max_num by more than 1000, then the form will fail to validate as if validate_max were set, and additionally only the first 1000 forms above max_num will be validated. The remainder will be truncated entirely. This is to protect against memory exhaustion attacks using forged POST requests.

validate_min

If validate_min=True is passed to formset_factory(), validation will also check that the number of forms in the data set, minus those marked for deletion, is greater than or equal to min_num.

>>> from django.forms import formset_factory
>>> from myapp.forms import ArticleForm
>>> ArticleFormSet = formset_factory(ArticleForm, min_num=3, validate_min=True)
>>> data = {
...     'form-TOTAL_FORMS': '2',
...     'form-INITIAL_FORMS': '0',
...     'form-MIN_NUM_FORMS': '',
...     'form-MAX_NUM_FORMS': '',
...     'form-0-title': 'Test',
...     'form-0-pub_date': '1904-06-16',
...     'form-1-title': 'Test 2',
...     'form-1-pub_date': '1912-06-23',
... }
>>> formset = ArticleFormSet(data)
>>> formset.is_valid()
False
>>> formset.errors
[{}, {}]
>>> formset.non_form_errors()
['Please submit 3 or more forms.']

Dealing with ordering and deletion of forms

The formset_factory() provides two optional parameters can_order and can_delete to help with ordering of forms in formsets and deletion of forms from a formset.

can_order

BaseFormSet.can_order

デフォルト値: False

Lets you create a formset with the ability to order:

>>> from django.forms import formset_factory
>>> from myapp.forms import ArticleForm
>>> ArticleFormSet = formset_factory(ArticleForm, can_order=True)
>>> formset = ArticleFormSet(initial=[
...     {'title': 'Article #1', 'pub_date': datetime.date(2008, 5, 10)},
...     {'title': '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="number" 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="number" 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="number" 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': '3',
...     'form-INITIAL_FORMS': '2',
...     'form-MAX_NUM_FORMS': '',
...     'form-0-title': 'Article #1',
...     'form-0-pub_date': '2008-05-10',
...     'form-0-ORDER': '2',
...     'form-1-title': 'Article #2',
...     'form-1-pub_date': '2008-05-11',
...     'form-1-ORDER': '1',
...     'form-2-title': 'Article #3',
...     'form-2-pub_date': '2008-05-01',
...     'form-2-ORDER': '0',
... }

>>> formset = ArticleFormSet(data, initial=[
...     {'title': 'Article #1', 'pub_date': datetime.date(2008, 5, 10)},
...     {'title': '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': 'Article #3'}
{'pub_date': datetime.date(2008, 5, 11), 'ORDER': 1, 'title': 'Article #2'}
{'pub_date': datetime.date(2008, 5, 10), 'ORDER': 2, 'title': 'Article #1'}

can_delete

BaseFormSet.can_delete

デフォルト値: False

Lets you create a formset with the ability to select forms for deletion:

>>> from django.forms import formset_factory
>>> from myapp.forms import ArticleForm
>>> ArticleFormSet = formset_factory(ArticleForm, can_delete=True)
>>> formset = ArticleFormSet(initial=[
...     {'title': 'Article #1', 'pub_date': datetime.date(2008, 5, 10)},
...     {'title': '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-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': '3',
...     'form-INITIAL_FORMS': '2',
...     'form-MAX_NUM_FORMS': '',
...     'form-0-title': 'Article #1',
...     'form-0-pub_date': '2008-05-10',
...     'form-0-DELETE': 'on',
...     'form-1-title': 'Article #2',
...     'form-1-pub_date': '2008-05-11',
...     'form-1-DELETE': '',
...     'form-2-title': '',
...     'form-2-pub_date': '',
...     'form-2-DELETE': '',
... }

>>> formset = ArticleFormSet(data, initial=[
...     {'title': 'Article #1', 'pub_date': datetime.date(2008, 5, 10)},
...     {'title': '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': 'Article #1'}]

If you are using a ModelFormSet, model instances for deleted forms will be deleted when you call formset.save().

If you call formset.save(commit=False), objects will not be deleted automatically. You'll need to call delete() on each of the formset.deleted_objects to actually delete them:

>>> instances = formset.save(commit=False)
>>> for obj in formset.deleted_objects:
...     obj.delete()

On the other hand, if you are using a plain FormSet, it's up to you to handle formset.deleted_forms, perhaps in your formset's save() method, as there's no general notion of what it means to delete a form.

Adding additional fields to a formset

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:

>>> from django.forms import BaseFormSet
>>> from django.forms import formset_factory
>>> from myapp.forms import ArticleForm
>>> class BaseArticleFormSet(BaseFormSet):
...     def add_fields(self, form, index):
...         super().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>

Passing custom parameters to formset forms

Sometimes your form class takes custom parameters, like MyArticleForm. You can pass this parameter when instantiating the formset:

>>> from django.forms import BaseFormSet
>>> from django.forms import formset_factory
>>> from myapp.forms import ArticleForm

>>> class MyArticleForm(ArticleForm):
...     def __init__(self, *args, user, **kwargs):
...         self.user = user
...         super().__init__(*args, **kwargs)

>>> ArticleFormSet = formset_factory(MyArticleForm)
>>> formset = ArticleFormSet(form_kwargs={'user': request.user})

The form_kwargs may also depend on the specific form instance. The formset base class provides a get_form_kwargs method. The method takes a single argument - the index of the form in the formset. The index is None for the empty_form:

>>> from django.forms import BaseFormSet
>>> from django.forms import formset_factory

>>> class BaseArticleFormSet(BaseFormSet):
...     def get_form_kwargs(self, index):
...         kwargs = super().get_form_kwargs(index)
...         kwargs['custom_kwarg'] = index
...         return kwargs

Customizing a formset's prefix

In the rendered HTML, formsets include a prefix on each field's name. By default, the prefix is 'form', but it can be customized using the formset's prefix argument.

For example, in the default case, you might see:

<label for="id_form-0-title">Title:</label>
<input type="text" name="form-0-title" id="id_form-0-title" />

But with ArticleFormset(prefix='article') that becomes:

<label for="id_article-0-title">Title:</label>
<input type="text" name="article-0-title" id="id_article-0-title" />

This is useful if you want to use more than one formset in a view.

Using a formset in views and templates

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:

from django.forms import formset_factory
from django.shortcuts import render
from myapp.forms import ArticleForm

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(request, '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 there's a slight shortcut for the above by letting 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.

Manually rendered can_delete and can_order

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 %}
        <ul>
            <li>{{ form.title }}</li>
            <li>{{ form.pub_date }}</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 }}.

Using more than one formset in a view

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:

from django.forms import formset_factory
from django.shortcuts import render
from myapp.forms import ArticleForm, BookForm

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(request, '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.

Each formset's prefix replaces the default form prefix that's added to each field's name and id HTML attributes.

Back to Top