烧瓶RESTful得到404错误？

Question

I followed the official docs of flask-RESTful and I'm trying to implement the first hello world demo.

At first, I put all the example code in a single file and every thing works fine.

However, when I split the code in three separated files (trying to make the project more structured), I always got a 404 error .

file stucture

.
├── app.py
├── app
    ├── __init__.py
    ├── __api__.py
└── venv

__init__.py

# -*- coding: utf-8 -*-
#initialization
from flask import Flask
from flask_restful import Resource, Api

app = Flask(__name__)
api = Api(app)

api.py

# -*- coding: utf-8 -*-
from app import app, api
from flask_restful import Resource, Api

class HelloWorld(Resource):
    def get(self):
        return {'hello': 'world'}

api.add_resource(HelloWorld, '/')

app.py

# -*- coding: utf-8 -*-
from app import app

if __name__ == '__main__':
    app.run(debug=True)

In python console:

 * Running on http://127.0.0.1:5000/ (Press CTRL+C to quit)
 * Restarting with stat
 * Debugger is active!
 * Debugger pin code: 250-643-552
127.0.0.1 - - [03/May/2016 22:35:20] "GET / HTTP/1.1" 404 -
127.0.0.1 - - [03/May/2016 22:35:24] "GET / HTTP/1.1" 404 -
127.0.0.1 - - [03/May/2016 22:38:15] "GET / HTTP/1.1" 404 -

What's wrong?

---

EDIT

I can now get the expected result by move api.add_resource(HelloWorld, '/') to app.py

app.py (edited)

# -*- coding: utf-8 -*-
from app import app, api
from app.api import HelloWorld

api.add_resource(HelloWorld, '/')


if __name__ == '__main__':
    app.run(debug=True)

Can't figure out why?

Answer 1

The reason why your previous version doesn't work is that module api.py is never loaded and thus below code (for mapping the URI to the given resource) does NOT get executed:

api.add_resource(HelloWorld, '/')

Actually in your edited/latest version, you don't have to rewrite that line of code in app.py. Instead you just need to import something from api.py.

Just a side note, normally it is more often that decorator api.resource is used to declare the mapping.