装饰器：flask / flask_login，使用login_required

Question

I want to use my rendering function both with and without the flask login_required decorator. My attempt was as follows: define the basic function, then assign to a new variable, wrapped with login_required :

import pymongo
from flask import render_template
from flask_login import login_required

def base_page(collection='posts'):
    db = pymongo.MongoClient().www
    title = collection.capitalize()
    page = db[collection].find().sort("created", pymongo.DESCENDING)
    return render_template('home/home.html', **locals())

base_page_login_required = login_required(base_page)

I then use these in my app.add_url_rule calls:

app.add_url_rule('/blog', view_func=base_page, defaults={'collection': 'posts'})
app.add_url_rule('/users', view_func=base_page_login_required, defaults={'collection': 'users'})

But obviously I've got something wrong:

Traceback (most recent call last):\r, referer: http://localhost/
   File "C:/www/flask/wsgi.py", line 26, in <module>\r, referer: http://localhost/
     app.add_url_rule('/users', view_func=base_page_login_required, defaults={'collection': 'users'})\r, referer: http://localhost/
   File "C:\\bin\\Python34\\lib\\site-packages\\flask\\app.py", line 62, in wrapper_func\r, referer: http://localhost/
     return f(self, *args, **kwargs)\r, referer: http://localhost/
   File "C:\\bin\\Python34\\lib\\site-packages\\flask\\app.py", line 984, in add_url_rule\r, referer: http://localhost/
     'existing endpoint function: %s' % endpoint)\r, referer: http://localhost/
 AssertionError: View function mapping is overwriting an existing endpoint function: base_page\r, referer: http://localhost/

Can anyone help me understand this error? I assume this is specific to flask and add_url_rule . I know I could just copy the first function code to a second and use the decorator normally, but I want to follow DRY.

Answer 1

Flask registers routes with an endpoint name; you use this name in url_for() to generate URLs.

By default, Flask uses the name of the function for this, the value of function.__name__ . Assigning a function to another name (even when decorated with a properly constructed decorator), does not give the function object a new name.

You can use the endpoint keyword argument to give your second registration a different name instead:

app.add_url_rule('/blog', view_func=base_page, 
                 defaults={'collection': 'posts'})
app.add_url_rule('/users', view_func=base_page_login_required,
                 endpoint='users',
                 defaults={'collection': 'users'})