Views

Take a request, return a response.

Plain views are written as classes, with a straightforward API that keeps simple views simple, but gives you the power of a full class to handle more complex cases.

from plain.views import View


class ExampleView(View):
    def get(self):
        return "Hello, world!"

HTTP methods -> class methods

The HTTP methd of the request will map to a class method of the same name on the view.

If a request comes in and there isn't a matching method on the view, Plain will return a 405 Method Not Allowed response.

from plain.views import View


class ExampleView(View):
    def get(self):
        pass

    def post(self):
        pass

    def put(self):
        pass

    def patch(self):
        pass

    def delete(self):
        pass

    def trace(self):
        pass

The base View class defines default options and head behavior, but you can override these too.

Return types

For simple plain text and JSON responses, you don't need to instantiate a Response object.

class TextView(View):
    def get(self):
        return "Hello, world!"


class JsonView(View):
    def get(self):
        return {"message": "Hello, world!"}

Template views

The most common behavior for a view is to render a template.

from plain.views import TemplateView


class ExampleView(TemplateView):
    template_name = "example.html"

    def get_template_context(self):
        context = super().get_template_context()
        context["message"] = "Hello, world!"
        return context

The TemplateView is also the base class for most of the other built-in view classes.

Form views

Standard forms can be rendered and processed by a FormView.

from plain.views import FormView
from .forms import ExampleForm


class ExampleView(FormView):
    template_name = "example.html"
    form_class = ExampleForm
    success_url = "."  # Redirect to the same page

    def form_valid(self, form):
        # Do other successfull form processing here
        return super().form_valid(form)

Rendering forms is done directly in the HTML.

{% extends "base.html" %}

{% block content %}

<form method="post">
    {{ csrf_input }}

    <!-- Render general form errors -->
    {% for error in form.non_field_errors %}
    <div>{{ error }}</div>
    {% endfor %}

    <!-- Render form fields individually (or with Jinja helps or other concepts) -->
    <label for="{{ form.email.html_id }}">Email</label>
    <input
        type="email"
        name="{{ form.email.html_name }}"
        id="{{ form.email.html_id }}"
        value="{{ form.email.value() or '' }}"
        autocomplete="email"
        autofocus
        required>
    {% if form.email.errors %}
    <div>{{ form.email.errors|join(', ') }}</div>
    {% endif %}

    <button type="submit">Save</button>
</form>

{% endblock %}

Object views

The object views support the standard CRUD (create, read/detail, update, delete) operations, plus a list view.

from plain.views import DetailView, CreateView, UpdateView, DeleteView, ListView


class ExampleDetailView(DetailView):
    template_name = "detail.html"

    def get_object(self):
        return MyObjectClass.objects.get(
            pk=self.url_kwargs["pk"],
            user=self.request.user,  # Limit access
        )


class ExampleCreateView(CreateView):
    template_name = "create.html"
    form_class = CustomCreateForm
    success_url = "."


class ExampleUpdateView(UpdateView):
    template_name = "update.html"
    form_class = CustomUpdateForm
    success_url = "."

    def get_object(self):
        return MyObjectClass.objects.get(
            pk=self.url_kwargs["pk"],
            user=self.request.user,  # Limit access
        )


class ExampleDeleteView(DeleteView):
    template_name = "delete.html"
    success_url = "."

    # No form class necessary.
    # Just POST to this view to delete the object.

    def get_object(self):
        return MyObjectClass.objects.get(
            pk=self.url_kwargs["pk"],
            user=self.request.user,  # Limit access
        )


class ExampleListView(ListView):
    template_name = "list.html"

    def get_objects(self):
        return MyObjectClass.objects.filter(
            user=self.request.user,  # Limit access
        )

Response exceptions

At any point in the request handling, a view can raise a ResponseException to immediately exit and return the wrapped response.

This isn't always necessary, but can be useful for raising rate limits or authorization errors when you're a couple layers deep in the view handling or helper functions.

from plain.views import DetailView
from plain.views.exceptions import ResponseException
from plain.http import Response


class ExampleView(DetailView):
    def get_object(self):
        if self.request.user.exceeds_rate_limit:
            raise ResponseException(
                Response("Rate limit exceeded", status=429)
            )

        return AnExpensiveObject()

Error views

By default, HTTP errors will be rendered by templates/<status_code>.html or templates/error.html.

You can define your own error views by pointing the HTTP_ERROR_VIEWS setting to a dictionary of status codes and view classes.

# app/settings.py
HTTP_ERROR_VIEWS = {
    404: "errors.NotFoundView",
}

# app/errors.py
from plain.views import View


class NotFoundView(View):
    def get(self):
        # A custom implementation or error view handling
        pass

Redirect views

from plain.views import RedirectView


class ExampleRedirectView(RedirectView):
    url = "/new-location/"
    permanent = True

CSRF exemption

from plain.views import View
from plain.views.csrf import CsrfExemptViewMixin


class ExemptView(CsrfExemptViewMixin, View):
    def post(self):
        return "Hello, world!"

Source

plain

views

redirect.py

 1import logging
 2
 3from plain.http import (
 4    ResponseGone,
 5    ResponsePermanentRedirect,
 6    ResponseRedirect,
 7)
 8from plain.urls import reverse
 9
10from .base import View
11
12logger = logging.getLogger("plain.request")
13
14
15class RedirectView(View):
16    """Provide a redirect on any GET request."""
17
18    permanent = False
19    url: str | None = None
20    pattern_name: str | None = None
21    query_string = False
22
23    def get_redirect_url(self):
24        """
25        Return the URL redirect to. Keyword arguments from the URL pattern
26        match generating the redirect request are provided as kwargs to this
27        method.
28        """
29        if self.url:
30            url = self.url % self.url_kwargs
31        elif self.pattern_name:
32            url = reverse(self.pattern_name, args=self.url_args, kwargs=self.url_kwargs)
33        else:
34            return None
35
36        args = self.request.META.get("QUERY_STRING", "")
37        if args and self.query_string:
38            url = f"{url}?{args}"
39        return url
40
41    def get(self):
42        url = self.get_redirect_url()
43        if url:
44            if self.permanent:
45                return ResponsePermanentRedirect(url)
46            else:
47                return ResponseRedirect(url)
48        else:
49            logger.warning(
50                "Gone: %s",
51                self.request.path,
52                extra={"status_code": 410, "request": self.request},
53            )
54            return ResponseGone()
55
56    def head(self):
57        return self.get()
58
59    def post(self):
60        return self.get()
61
62    def options(self):
63        return self.get()
64
65    def delete(self):
66        return self.get()
67
68    def put(self):
69        return self.get()
70
71    def patch(self):
72        return self.get()