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。
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 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。
Given a contact form:
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。
from myapp.forms import ContactForm
from django.views.generic.edit import FormView
class ContactFormView(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:
TemplateResponseMixin を継承するため、ここでは template_name を使うことができます。form_valid() デフォルトの実装は、ただ単に success_url にリダイレクトするというものです。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 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 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() 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 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() 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 or
UpdateView - they will use
get_absolute_url() on the model object if available.
If you want to use a custom ModelForm (for instance to
add extra validation), set
form_class on your view.
注釈
カスタムのフォームクラスを指定した場合、form_class が 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() を追加する必要があります:
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 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:
from django.urls import reverse_lazy
from django.views.generic.edit import CreateView, DeleteView, UpdateView
from myapp.models import Author
class AuthorCreateView(CreateView):
model = Author
fields = ['name']
class AuthorUpdateView(UpdateView):
model = Author
fields = ['name']
class AuthorDeleteView(DeleteView):
model = Author
success_url = reverse_lazy('author-list')
注釈
We have to use 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. Unless you define the
form class in another way, the attribute is required and the view will raise
an ImproperlyConfigured exception if it's not.
If you specify both the fields
and form_class attributes, an
ImproperlyConfigured exception will be raised.
Finally, we hook these new views into the URLconf:
from django.urls import path
from myapp.views import AuthorCreateView, AuthorDeleteView, AuthorUpdateView
urlpatterns = [
# ...
path('author/add/', AuthorCreateView.as_view(), name='author-add'),
path('author/<int:pk>/', AuthorUpdateView.as_view(), name='author-update'),
path('author/<int:pk>/delete/', AuthorDeleteView.as_view(), name='author-delete'),
]
注釈
These views inherit
SingleObjectTemplateResponseMixin
which uses
template_name_suffix
to construct the
template_name
based on the model.
In this example:
CreateView and UpdateView use myapp/author_form.htmlDeleteView uses myapp/author_confirm_delete.htmlIf you wish to have separate templates for CreateView and
UpdateView, you can set either
template_name or
template_name_suffix
on your view class.
request.user¶To track the user that created an object using a CreateView,
you can use a custom ModelForm to do this. First, add
the foreign key relation to the model:
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() to add the user:
from django.contrib.auth.mixins import LoginRequiredMixin
from django.views.generic.edit import CreateView
from myapp.models import Author
class AuthorCreateView(LoginRequiredMixin, CreateView):
model = Author
fields = ['name']
def form_valid(self, form):
form.instance.created_by = self.request.user
return super().form_valid(form)
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().
Here is an example showing how you might go about implementing a form that works with an API-based workflow as well as 'normal' form POSTs:
from django.http import JsonResponse
from django.views.generic.edit import CreateView
from myapp.models import Author
class JsonableResponseMixin:
"""
Mixin to add JSON 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.accepts('text/html'):
return response
else:
return JsonResponse(form.errors, status=400)
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.accepts('text/html'):
return response
else:
data = {
'pk': self.object.pk,
}
return JsonResponse(data)
class AuthorCreateView(JsonableResponseMixin, CreateView):
model = Author
fields = ['name']
2022年6月01日