Built-in Views

Several of Django’s built-in views are documented in Escrevendo “views” as well as elsewhere in the documentation.

Serving files in development

static.serve(request, path, document_root, show_indexes=False)

There may be files other than your project’s static assets that, for convenience, you’d like to have Django serve for you in local development. The serve() view can be used to serve any directory you give it. (This view is not hardened for production use and should be used only as a development aid; you should serve these files in production using a real front-end web server).

The most likely example is user-uploaded content in MEDIA_ROOT. django.contrib.staticfiles is intended for static assets and has no built-in handling for user-uploaded files, but you can have Django serve your MEDIA_ROOT by appending something like this to your URLconf:

from django.conf import settings
from django.urls import re_path
from django.views.static import serve

# ... the rest of your URLconf goes here ...

if settings.DEBUG:
    urlpatterns += [
        re_path(r'^media/(?P<path>.*)$', serve, {
            'document_root': settings.MEDIA_ROOT,
        }),
    ]

Note, the snippet assumes your MEDIA_URL has a value of '/media/'. This will call the serve() view, passing in the path from the URLconf and the (required) document_root parameter.

Since it can become a bit cumbersome to define this URL pattern, Django ships with a small URL helper function static() that takes as parameters the prefix such as MEDIA_URL and a dotted path to a view, such as 'django.views.static.serve'. Any other function parameter will be transparently passed to the view.

Error views

Django comes with a few views by default for handling HTTP errors. To override these with your own custom views, see Personalizando “views” de erro.

A view 404 (página não encontrada)

defaults.page_not_found(request, exception, template_name='404.html')

When you raise Http404 from within a view, Django loads a special view devoted to handling 404 errors. By default, it’s the view django.views.defaults.page_not_found(), which either produces a “Not Found” message or loads and renders the template 404.html if you created it in your root template directory.

The default 404 view will pass two variables to the template: request_path, which is the URL that resulted in the error, and exception, which is a useful representation of the exception that triggered the view (e.g. containing any message passed to a specific Http404 instance).

Three things to note about 404 views:

• The 404 view is also called if Django doesn’t find a match after checking every regular expression in the URLconf.
• The 404 view is passed a RequestContext and will have access to variables supplied by your template context processors (e.g. MEDIA_URL).
• If DEBUG is set to True (in your settings module), then your 404 view will never be used, and your URLconf will be displayed instead, with some debug information.

A view 500 (erro no servidor)

defaults.server_error(request, template_name='500.html')

Similarly, Django executes special-case behavior in the case of runtime errors in view code. If a view results in an exception, Django will, by default, call the view django.views.defaults.server_error, which either produces a “Server Error” message or loads and renders the template 500.html if you created it in your root template directory.

A view padrão 500, não passa nenhuma variável ao template “500.html”, dessa forma, será renderizado um “Context” vazio para reduzir a chance de erros adicionais.

If DEBUG is set to True (in your settings module), then your 500 view will never be used, and the traceback will be displayed instead, with some debug information.

The 403 (HTTP Forbidden) view

defaults.permission_denied(request, exception, template_name='403.html')

In the same vein as the 404 and 500 views, Django has a view to handle 403 Forbidden errors. If a view results in a 403 exception then Django will, by default, call the view django.views.defaults.permission_denied.

Essa view carrega e renderiza o template 403.html

django.views.defaults.permission_denied is triggered by a PermissionDenied exception. To deny access in a view you can use code like this:

from django.core.exceptions import PermissionDenied

def edit(request, pk):
    if not request.user.is_staff:
        raise PermissionDenied
    # ...

A view 400 (pedido ruim)

defaults.bad_request(request, exception, template_name='400.html')

When a SuspiciousOperation is raised in Django, it may be handled by a component of Django (for example resetting the session data). If not specifically handled, Django will consider the current request a ‘bad request’ instead of a server error.

django.views.defaults.bad_request é entretanto, muito similar a server_error view, contudo, ele retorna com o status code 400, indicando que a condição do erro é resultado de uma operação do cliente. Por padrão, nada relacionado à excessão que disparou a view é passado ao template context, uma vez que a mensagem de excessão pode conter informações importantes como “filesystem paths”.

bad_request views são também utilizadas somente quando DEBUG is False.