# Dokumentasi Django 5.2.8

# Menangani formulir dengan tampilan berdasarkan-kelas

Pengolahan formulir umumnya mempunyai 3 jalur:

- Inisial GET (kosong atau formulir diisi dimuka)

- POST dengan data tidak sah (khususnya memperlihatkan kembali formulir dengan kesalahan)

- POST dengan data sah (pengolahan data dan khususnya pengalihan)

Menerapkan ini anda sendiri sering menghasilkan banyak perulangan kode boilerplate (lihat Using a form in a view). Untuk menghindai ini, Django menyediakan kumpulan dari tampilan berdasarkan-kelas umum untuk pengolahan formulir.

## Formulir dasar

Diberikan formulir kontak:

`forms.py`

    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

Tampilan dapat dibangun menggunakan `FormView`:

`views.py`

    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)

Catatan:

- FormView mewarisi `TemplateResponseMixin` jadi `template_name` dapat digunakan disini.

- Penerapan awalan untuk `form_valid()` cukup mengalihkan ke `success_url`.

## Formulir model

Generic views really shine when working with models. These generic views will automatically create a `ModelForm`, so long as they can work out which model class to use:

- Jika atribut `model` diberikan, kelas model itu akan digunakan.

- If `get_object()` returns an object, the class of that object will be used.

- Jika sebuah `queryset` diberikan, model untuk queryset itu akan digunakan.

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.

Jika anda ingin menggunakan penyesuaian `ModelForm` (misalnya untuk menambahkan validasi ekstra), atur `form_class` pada tampilan anda.

Catatan

Ketika menentukan sebuah penyesuaian kelas formulir, anda harus masih menentukan model, meskipun `form_class` mungkin berupa sebuah `ModelForm`.

First we need to add `get_absolute_url()` to our `Author` class:

`models.py`

    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})

Kemudian kami dapat menggunakan `CreateView` dan teman-teman untuk melakukan pekerjaan sebenarnya. Perhatikan bagaimana kami hanya mengkonfigurasi tampilan berdasarkan-kelas umum disini; kami tidak harus menulis logika apapun kami sendiri:

`views.py`

    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")

Catatan

Kami harus menggunakan `reverse_lazy()` daripada `reverse()`, ketika url tidak dimuat ketika berkas diimpor.

Atribut `fields` bekerja cara sama seperti atribut `fields` pada kelas `Meta` sebelah dalam pada `ModelForm`. Meskipun anda menentukan kelas formulir di cara lain, atribut dibutuhkan dan tampilan akan munculkan sebuah pengecualian `ImproperlyConfigured` jika itu tidak.

Jika anda menentukan kedua atribut `fields` dan `form_class`, sebuah pengecualian `ImproperlyConfigured` akan dimunculkan.

Akhirnya, kami mengaitkan tampilan baru ini kedalam URLconf:

`urls.py`

    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"),
    ]

Catatan

Tampilan ini mewarisi class:~django.views.generic.detail.SingleObjectTemplateResponseMixin yang menggunakan `template_name_suffix` untuk membangun `template_name` berdasarkan pada model.

Di contoh ini:

- `CreateView` dan `UpdateView` menggunakan `myapp/author_form.html`

- `DeleteView` menggunakan `myapp/author_confirm_delete.html`

Jika anda berharap untuk mempunyai cetakan terpisah untuk `CreateView` dan `UpdateView`, anda dapat menyetel antara `template_name` atau `template_name_suffix` pada kelas tampilan anda.

## Models dan `request.user`

Untuk melacak pengguna yang membuat sebuah obyek menggunakan sebuah `CreateView`, anda dapat menggunakan sebuah penyesuaian `ModelForm` untuk melakukan ini. Pertama, tambah hubungan foreign key pada model:

`models.py`

    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:

`views.py`

    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()`.

## Contoh negosiasi isi

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"]

The above example assumes that if the client supports `text/html`, that they would prefer it. However, this may not always be true. When requesting a `.css` file, many browsers will send the header `Accept: text/css,*/*;q=0.1`, indicating that they would prefer CSS, but anything else is fine. This means `request.accepts("text/html")` will be `True`.

To determine the correct format, taking into consideration the client's preference, use `django.http.HttpRequest.get_preferred_type()`:

    class JsonableResponseMixin:
        """
        Mixin to add JSON support to a form.
        Must be used with an object-based FormView (e.g. CreateView).
        """

        accepted_media_types = ["text/html", "application/json"]

        def dispatch(self, request, *args, **kwargs):
            if request.get_preferred_type(self.accepted_media_types) is None:
                # No format in common.
                return HttpResponse(
                    status_code=406, headers={"Accept": ",".join(self.accepted_media_types)}
                )

            return super().dispatch(request, *args, **kwargs)

        def form_invalid(self, form):
            response = super().form_invalid(form)
            accepted_type = self.request.get_preferred_type(self.accepted_media_types)
            if accepted_type == "text/html":
                return response
            elif accepted_type == "application/json":
                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)
            accepted_type = self.request.get_preferred_type(self.accepted_media_types)
            if accepted_type == "text/html":
                return response
            elif accepted_type == "application/json":
                data = {
                    "pk": self.object.pk,
                }
                return JsonResponse(data)

Changed in Django 5.2:

The `HttpRequest.get_preferred_type()` method was added.