---
title: "クラスベースビュー"
version: 3.0
locale: ja
source: https://docs.djangoproject.com/ja/3.0/topics/class-based-views/
canonical: https://djangodocs.dev/ja/3.0/topics/class-based-views/
---
# クラスベースビュー

A view is a callable which takes a request and returns a
response. This can be more than just a function, and Django provides
an example of some classes which can be used as views. These allow you
to structure your views and reuse code by harnessing inheritance and
mixins. There are also some generic views for tasks which we'll get to later,
but you may want to design your own structure of reusable views which suits
your use case. For full details, see the [class-based views reference
documentation](/ja/3.0/ref/class-based-views/).

- [クラスベースビュー入門](/ja/3.0/topics/class-based-views/intro/)
- [ビルトインのクラスベースのジェネリックビュー](/ja/3.0/topics/class-based-views/generic-display/)
- [クラスベースのビューでフォームを扱う](/ja/3.0/topics/class-based-views/generic-editing/)
- [クラスベースのビューでミックスインを使用する](/ja/3.0/topics/class-based-views/mixins/)

## 基本的な例

Django provides base view classes which will suit a wide range of applications.
All views inherit from the [`View`](/ja/3.0/ref/class-based-views/base/#django.views.generic.base.View) class, which
handles linking the view into the URLs, HTTP method dispatching and other
common features. [`RedirectView`](/ja/3.0/ref/class-based-views/base/#django.views.generic.base.RedirectView) provides a
HTTP redirect, and [`TemplateView`](/ja/3.0/ref/class-based-views/base/#django.views.generic.base.TemplateView) extends the
base class to make it also render a template.

## Usage in your URLconf

The most direct way to use generic views is to create them directly in your
URLconf. If you're only changing a few attributes on a class-based view, you
can pass them into the [`as_view()`](/ja/3.0/ref/class-based-views/base/#django.views.generic.base.View.as_view) method
call itself:

```
from django.urls import path
from django.views.generic import TemplateView

urlpatterns = [
    path('about/', TemplateView.as_view(template_name="about.html")),
]
```

[`as_view()`](/ja/3.0/ref/class-based-views/base/#django.views.generic.base.View.as_view) に渡されたすべての引数は、クラスで設定された属性を上書きします。次の例では `TemplateView` の `template_name` を設定しています。同様の上書きのパターンは、[`RedirectView`](/ja/3.0/ref/class-based-views/base/#django.views.generic.base.RedirectView) の `url` 属性でも使えます。

## ジェネリックビューのサブクラス化

The second, more powerful way to use generic views is to inherit from an
existing view and override attributes (such as the `template_name`) or
methods (such as `get_context_data`) in your subclass to provide new values
or methods. Consider, for example, a view that just displays one template,
`about.html`. Django has a generic view to do this -
[`TemplateView`](/ja/3.0/ref/class-based-views/base/#django.views.generic.base.TemplateView) \- so we can subclass it, and
override the template name:

```
# some_app/views.py
from django.views.generic import TemplateView

class AboutView(TemplateView):
    template_name = "about.html"
```

Then we need to add this new view into our URLconf.
[`TemplateView`](/ja/3.0/ref/class-based-views/base/#django.views.generic.base.TemplateView) is a class, not a function, so
we point the URL to the [`as_view()`](/ja/3.0/ref/class-based-views/base/#django.views.generic.base.View.as_view) class
method instead, which provides a function-like entry to class-based views:

```
# urls.py
from django.urls import path
from some_app.views import AboutView

urlpatterns = [
    path('about/', AboutView.as_view()),
]
```

組み込みのジェネリックビューの使用方法の詳細については、次のトピック [generic class-based views](/ja/3.0/topics/class-based-views/generic-display/) を参照してください。

### その他の HTTP メソッドをサポートする

誰かが私たちの図書館に HTTP 経由でアクセスして、ビューを API として使用したいという状況を考えてください。API クライアントはたびたびコネクションを張り、最終訪問日時以降に出版された本のデータをダウンロードするとします。しかし、新しい本の情報が存在しない場合には、データベースから本のデータを取得し、レスポンステキストをレンダリングし、クライアントに送信し返すための CPU タイムとバンド幅は無駄になってしまいます。最新の本が出版された時点で API に問い合わせた方が好ましいかもしれません。

そのために、URLconf 内で、本のリストビューへの URL を次のようにマッピングします。

```
from django.urls import path
from books.views import BookListView

urlpatterns = [
    path('books/', BookListView.as_view()),
]
```

そして、ビューには次のように書きます。

```
from django.http import HttpResponse
from django.views.generic import ListView
from books.models import Book

class BookListView(ListView):
    model = Book

    def head(self, *args, **kwargs):
        last_book = self.get_queryset().latest('publication_date')
        response = HttpResponse()
        # RFC 1123 date format
        response['Last-Modified'] = last_book.publication_date.strftime('%a, %d %b %Y %H:%M:%S GMT')
        return response
```

If the view is accessed from a `GET` request, an object list is returned in
the response (using the `book_list.html` template). But if the client issues
a `HEAD` request, the response has an empty body and the `Last-Modified`
header indicates when the most recent book was published.  Based on this
information, the client may or may not download the full object list.