Flask Academy · レッスン

Blueprintを作成して登録する

Blueprintを定義し、アプリに接続します

「Blueprintを作成して登録する」はCoddyKit上の無料Flask Academyレッスンです。これはレッスン2/4です。下記で完全なレッスンを無料で読むことができます。その後、ブラウザ内の組み込みコードエディタと24時間対応のAIチューターでハンズオン演習できます。これはFlask Academy学習パスの一部であり、ウェブとCoddyKitアプリ全体で進捗が同期されます。 Flask Academyコースには全4レッスンが含まれています。

このレッスンの一部はまだ翻訳されておらず、英語で表示されています。

Two Steps to a Blueprint

Working with a blueprint is two moves: first you define it in its own module, then you register it on the app. Let us walk through both.

Import the Blueprint Class

Everything starts with one import. The Blueprint class comes straight from flask, just like the Flask app object does.

from flask import Blueprint

Create the Blueprint Object

You build a blueprint by giving it a name and import_name. The name uniquely identifies this blueprint inside your whole app.

blog = Blueprint("blog", __name__)

What name Does

That second argument, __name__, tells the blueprint where it lives so Flask can later find its templates and static files.

Routes on the Blueprint

Inside the module you attach views with @blog.route instead of @app.route. Same idea, but bound to the blueprint.

@blog.route("/posts")
def posts():
    return "All posts"

Still Dormant for Now

Defining routes is not enough. Until you register the blueprint, none of its URLs respond. The blueprint is inert on its own.

Import It in the App

Over in your app setup, you import the blueprint object from its module so the app can take ownership of it.

from blog.routes import blog

Register on the App

One call wires everything up. register_blueprint copies the blueprint routes onto the app and makes them live.

app.register_blueprint(blog)

Order of Operations

Create the app, import the blueprint, then register it. Get this sequence right and your feature routes spring to life. ✅

Endpoint Names Get Namespaced

A view named posts inside the blog blueprint is referenced as blog.posts. The blueprint name becomes a tidy prefix for endpoints.

Avoiding Circular Imports

Keep the blueprint in its own file and import it where you build the app. This structure sidesteps painful circular import errors.

Quick Check

Which call actually makes a blueprint active?

Recap

Define a Blueprint with a name and __name__, add routes with @bp.route, then call register_blueprint on the app to make them live. 🎉

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