Flask Class-Based Views API
Flask provides two kinds of class-based views, allowing you to organize view logic in an object-oriented way.
ViewIs the most basic class-based view,MethodViewAutomatically dispatches according to HTTP methods.
View base class
| Attributes/Methods | Description |
|---|---|
| methods | Class attribute, the list of HTTP methods accepted by the view. Default None (uses the default value of add_url_rule) |
| decorators | Class attribute, the list of decorators. Applied in order to the generated view function |
| init_every_request | Class attribute, bool. When True (default), a new instance is created for each request; when False, a single instance is reused. |
| provide_automatic_options | Class attribute, whether to automatically implement OPTIONS. Default None (uses the app configuration) |
| dispatch_request(**kwargs) | Core method, must be overridden. kwargs are the URL variables |
| as_view(name, *class_args, **class_kwargs) | Class method, creates a view function that can be used in add_url_rule |
MethodView class
Inherits from View, automatically dispatches to the corresponding instance method according to HTTP method.
| Method Naming Conventions | Description |
|---|---|
| get(self, **kwargs) | Handles GET requests |
| post(self, **kwargs) | Handles POST requests |
| put(self, **kwargs) | Handles PUT requests |
| delete(self, **kwargs) | Handles DELETE requests |
| patch(self, **kwargs) | Handles PATCH requests |
After defining these methods,methodsThe attribute is automatically set based on the defined methods.
View vs MethodView
| Features | View | MethodView |
|---|---|---|
| Dispatch method | A single dispatch_request handles all methods | Automatically dispatches by method name (get→GET, etc.) |
| Applicable scenarios | Generic views, template rendering | RESTful API |
Code Examples
Example
from flask import Flask, request, session, redirect, url_for
from flask.views import View, MethodView
app = Flask(__name__)
# Basic View: single dispatch_request
class HelloView(View):
def dispatch_request(self, name):
return f"<h1>Hello, {name}!</h1>"
app.add_url_rule("/hello/<name>", view_func=HelloView.as_view("hello"))
# MethodView：RESTful API
class PostAPI(MethodView):
# Custom initialization (called on every request)
def __init__(self):
self.db = get_database_connection()
def get(self, post_id=None):
if post_id is None:
posts = self.db.query_all_posts()
return {"posts": posts}
return self.db.get_post(post_id)
def post(self):
data = request.json
post_id = self.db.create_post(data["title"], data["body"])
return {"id": post_id}, 201
def delete(self, post_id):
self.db.delete_post(post_id)
return {"message": "deleted"}
# Registration: the same view function handles multiple methods
post_view = PostAPI.as_view("post_api")
app.add_url_rule("/api/posts", defaults={"post_id": None},
view_func=post_view, methods=["GET", "POST"])
app.add_url_rule("/api/posts/<int:post_id>",
view_func=post_view, methods=["GET", "DELETE"])
from flask.views import View, MethodView
app = Flask(__name__)
# Basic View: single dispatch_request
class HelloView(View):
def dispatch_request(self, name):
return f"<h1>Hello, {name}!</h1>"
app.add_url_rule("/hello/<name>", view_func=HelloView.as_view("hello"))
# MethodView：RESTful API
class PostAPI(MethodView):
# Custom initialization (called on every request)
def __init__(self):
self.db = get_database_connection()
def get(self, post_id=None):
if post_id is None:
posts = self.db.query_all_posts()
return {"posts": posts}
return self.db.get_post(post_id)
def post(self):
data = request.json
post_id = self.db.create_post(data["title"], data["body"])
return {"id": post_id}, 201
def delete(self, post_id):
self.db.delete_post(post_id)
return {"message": "deleted"}
# Registration: the same view function handles multiple methods
post_view = PostAPI.as_view("post_api")
app.add_url_rule("/api/posts", defaults={"post_id": None},
view_func=post_view, methods=["GET", "POST"])
app.add_url_rule("/api/posts/<int:post_id>",
view_func=post_view, methods=["GET", "DELETE"])