---
title: "クラスベースのビューでフォームを扱う"
version: 3.0
locale: ja
source: https://docs.djangoproject.com/ja/3.0/topics/class-based-views/generic-editing/
canonical: https://djangodocs.dev/ja/3.0/topics/class-based-views/generic-editing/
---
# クラスベースのビューでフォームを扱う

フォームの処理には、一般に3つの場合分けが存在します。

- 最初の GET リクエスト (空白またはデフォルト値が埋め込まれたフォームを返す)
- 無効なデータの POST リクエスト (よくあるパターンは、エラー表示を追加したフォームを再表示する)
- 有効なデータの POST リクエスト (データを処理し、普通はリダイレクトを行う)

これらの処理を自分で実装しようとすると、多くの場合、多数の繰り返しの定型コードを書くことになってしまいます ([Using a form in a view](/ja/3.0/topics/forms/#using-a-form-in-a-view) を参照)。これを避けるために、Django はフォームを処理するための一般的なクラスビューを用意しています。

## 基本的なフォーム

Given a contact form:

*forms.py*

```python
from django import forms

class ContactForm(forms.Form):
    name = forms.CharField()
    message = forms.CharField(widget=forms.Textarea)

    def send_email(self):
        # send email using the self.cleaned_data dictionary
        pass
```

このとき、ビューは `FormView` を使用することで構築することができます。

*views.py*

```python
from myapp.forms import ContactForm
from django.views.generic.edit import FormView

class ContactView(FormView):
    template_name = 'contact.html'
    form_class = ContactForm
    success_url = '/thanks/'

    def form_valid(self, form):
        # This method is called when valid form data has been POSTed.
        # It should return an HttpResponse.
        form.send_email()
        return super().form_valid(form)
```

メモ:

- FormView は [`TemplateResponseMixin`](/ja/3.0/ref/class-based-views/mixins-simple/#django.views.generic.base.TemplateResponseMixin) を継承するため、ここでは [`template_name`](/ja/3.0/ref/class-based-views/mixins-simple/#django.views.generic.base.TemplateResponseMixin.template_name) を使うことができます。
- [`form_valid()`](/ja/3.0/ref/class-based-views/mixins-editing/#django.views.generic.edit.FormMixin.form_valid) デフォルトの実装は、ただ単に [`success_url`](/ja/3.0/ref/class-based-views/mixins-editing/#django.views.generic.edit.FormMixin.success_url) にリダイレクトするというものです。

## モデルフォーム

ジェネリックビューが輝きを見せるのは、モデルとともに使用した時です。ジェネリックビューは  [`ModelForm`](/ja/3.0/topics/forms/modelforms/#django.forms.ModelForm) を自動的に生成するので、どのモデルクラスを使うのかを選択することができます。

- [`model`](/ja/3.0/ref/class-based-views/mixins-editing/#django.views.generic.edit.ModelFormMixin.model) 属性が与えられた場合には、そのモデルクラスが使用されます。
- [`get_object()`](/ja/3.0/ref/class-based-views/mixins-single-object/#django.views.generic.detail.SingleObjectMixin.get_object) がオブジェクトを帰す場合には、そのオブジェクトのクラスが使用されます。
- [`queryset`](/ja/3.0/ref/class-based-views/mixins-single-object/#django.views.generic.detail.SingleObjectMixin.queryset) が与えられた場合には、そのクエリセットに対するモデルが使用されます。

Model form views provide a
[`form_valid()`](/ja/3.0/ref/class-based-views/mixins-editing/#django.views.generic.edit.ModelFormMixin.form_valid) implementation
that saves the model automatically.  You can override this if you have any
special requirements; see below for examples.

You don't even need to provide a `success_url` for
[`CreateView`](/ja/3.0/ref/class-based-views/generic-editing/#django.views.generic.edit.CreateView) or
[`UpdateView`](/ja/3.0/ref/class-based-views/generic-editing/#django.views.generic.edit.UpdateView) \- they will use
[`get_absolute_url()`](/ja/3.0/ref/models/instances/#django.db.models.Model.get_absolute_url) on the model object if available.

If you want to use a custom [`ModelForm`](/ja/3.0/topics/forms/modelforms/#django.forms.ModelForm) (for instance to
add extra validation), set
[`form_class`](/ja/3.0/ref/class-based-views/mixins-editing/#django.views.generic.edit.FormMixin.form_class) on your view.

> **Note**
>
> カスタムのフォームクラスを指定した場合、[`form_class`](/ja/3.0/ref/class-based-views/mixins-editing/#django.views.generic.edit.FormMixin.form_class) が [`ModelForm`](/ja/3.0/topics/forms/modelforms/#django.forms.ModelForm) だったとしても、モデルを指定する必要があります。

最初に、`Author` クラスに [`get_absolute_url()`](/ja/3.0/ref/models/instances/#django.db.models.Model.get_absolute_url) を追加する必要があります:

*models.py*

```python
from django.db import models
from django.urls import reverse

class Author(models.Model):
    name = models.CharField(max_length=200)

    def get_absolute_url(self):
        return reverse('author-detail', kwargs={'pk': self.pk})
```

そうしたら、[`CreateView`](/ja/3.0/ref/class-based-views/flattened-index/#CreateView) およびその仲間たちを使って実際に動作させることができます。ここでは一般的なクラスベースのビューのみを設定している点が重要です; 自分自身でロジックを書く必要はありません:

*views.py*

```python
from django.urls import reverse_lazy
from django.views.generic.edit import CreateView, DeleteView, UpdateView
from myapp.models import Author

class AuthorCreate(CreateView):
    model = Author
    fields = ['name']

class AuthorUpdate(UpdateView):
    model = Author
    fields = ['name']

class AuthorDelete(DeleteView):
    model = Author
    success_url = reverse_lazy('author-list')
```

> **Note**
>
> We have to use [`reverse_lazy()`](/ja/3.0/ref/urlresolvers/#django.urls.reverse_lazy) instead of
> `reverse()`, as the urls are not loaded when the file is imported.

The `fields` attribute works the same way as the `fields` attribute on the
inner `Meta` class on [`ModelForm`](/ja/3.0/topics/forms/modelforms/#django.forms.ModelForm). Unless you define the
form class in another way, the attribute is required and the view will raise
an [`ImproperlyConfigured`](/ja/3.0/ref/exceptions/#django.core.exceptions.ImproperlyConfigured) exception if it's not.

If you specify both the [`fields`](/ja/3.0/ref/class-based-views/mixins-editing/#django.views.generic.edit.ModelFormMixin.fields)
and [`form_class`](/ja/3.0/ref/class-based-views/mixins-editing/#django.views.generic.edit.FormMixin.form_class) attributes, an
[`ImproperlyConfigured`](/ja/3.0/ref/exceptions/#django.core.exceptions.ImproperlyConfigured) exception will be raised.

Finally, we hook these new views into the URLconf:

*urls.py*

```python
from django.urls import path
from myapp.views import AuthorCreate, AuthorDelete, AuthorUpdate

urlpatterns = [
    # ...
    path('author/add/', AuthorCreate.as_view(), name='author-add'),
    path('author/<int:pk>/', AuthorUpdate.as_view(), name='author-update'),
    path('author/<int:pk>/delete/', AuthorDelete.as_view(), name='author-delete'),
]
```

> **Note**
>
> These views inherit
> [`SingleObjectTemplateResponseMixin`](/ja/3.0/ref/class-based-views/mixins-single-object/#django.views.generic.detail.SingleObjectTemplateResponseMixin)
> which uses
> [`template_name_suffix`](/ja/3.0/ref/class-based-views/mixins-single-object/#django.views.generic.detail.SingleObjectTemplateResponseMixin.template_name_suffix)
> to construct the
> [`template_name`](/ja/3.0/ref/class-based-views/mixins-simple/#django.views.generic.base.TemplateResponseMixin.template_name)
> based on the model.
>
> In this example:
>
> - [`CreateView`](/ja/3.0/ref/class-based-views/flattened-index/#CreateView) and [`UpdateView`](/ja/3.0/ref/class-based-views/flattened-index/#UpdateView) use `myapp/author_form.html`
> - [`DeleteView`](/ja/3.0/ref/class-based-views/flattened-index/#DeleteView) uses `myapp/author_confirm_delete.html`
>
> If you wish to have separate templates for [`CreateView`](/ja/3.0/ref/class-based-views/flattened-index/#CreateView) and
> [`UpdateView`](/ja/3.0/ref/class-based-views/flattened-index/#UpdateView), you can set either
> [`template_name`](/ja/3.0/ref/class-based-views/mixins-simple/#django.views.generic.base.TemplateResponseMixin.template_name) or
> [`template_name_suffix`](/ja/3.0/ref/class-based-views/mixins-single-object/#django.views.generic.detail.SingleObjectTemplateResponseMixin.template_name_suffix)
> on your view class.

## Models and `request.user`

To track the user that created an object using a [`CreateView`](/ja/3.0/ref/class-based-views/flattened-index/#CreateView),
you can use a custom [`ModelForm`](/ja/3.0/topics/forms/modelforms/#django.forms.ModelForm) to do this. First, add
the foreign key relation to the model:

*models.py*

```python
from django.contrib.auth.models import User
from django.db import models

class Author(models.Model):
    name = models.CharField(max_length=200)
    created_by = models.ForeignKey(User, on_delete=models.CASCADE)

    # ...
```

In the view, ensure that you don't include `created_by` in the list of fields
to edit, and override
[`form_valid()`](/ja/3.0/ref/class-based-views/mixins-editing/#django.views.generic.edit.ModelFormMixin.form_valid) to add the user:

*views.py*

```python
from django.contrib.auth.mixins import LoginRequiredMixin
from django.views.generic.edit import CreateView
from myapp.models import Author

class AuthorCreate(LoginRequiredMixin, CreateView):
    model = Author
    fields = ['name']

    def form_valid(self, form):
        form.instance.created_by = self.request.user
        return super().form_valid(form)
```

[`LoginRequiredMixin`](/ja/3.0/topics/auth/default/#django.contrib.auth.mixins.LoginRequiredMixin) prevents users who
aren't logged in from accessing the form. If you omit that, you'll need to
handle unauthorized users in [`form_valid()`](/ja/3.0/ref/class-based-views/mixins-editing/#django.views.generic.edit.ModelFormMixin.form_valid).

## AJAX の例

Here is an example showing how you might go about implementing a form that
works for AJAX requests as well as 'normal' form POSTs:

```
from django.http import JsonResponse
from django.views.generic.edit import CreateView
from myapp.models import Author

class AjaxableResponseMixin:
    """
    Mixin to add AJAX support to a form.
    Must be used with an object-based FormView (e.g. CreateView)
    """
    def form_invalid(self, form):
        response = super().form_invalid(form)
        if self.request.is_ajax():
            return JsonResponse(form.errors, status=400)
        else:
            return response

    def form_valid(self, form):
        # We make sure to call the parent's form_valid() method because
        # it might do some processing (in the case of CreateView, it will
        # call form.save() for example).
        response = super().form_valid(form)
        if self.request.is_ajax():
            data = {
                'pk': self.object.pk,
            }
            return JsonResponse(data)
        else:
            return response

class AuthorCreate(AjaxableResponseMixin, CreateView):
    model = Author
    fields = ['name']
```