Flask Blueprint AttributeError: 'module' object has no attribute 'name' error

Question

My API is being built to allow developers to extend it's functionality. My plan is to do this by providing an "extensions" directory where they can drop in Blueprints and they will be dynamically loaded. This is the code I am utilizing to import (modifed from this tutorial)

from flask import Flask

import pkgutil
import sys

app = Flask(__name__)

EXTENSIONS_DIR = "extensions"
modules = pkgutil.iter_modules(path=[EXTENSIONS_DIR])
for loader, mod_name, ispkg in modules: 
    if mod_name not in sys.modules:
        # It imports fine
        loaded_mod = __import__(EXTENSIONS_DIR+"."+mod_name+"."+mod_name, fromlist=[mod_name])
        # It does not register
        app.register_blueprint(loaded_mod)

This is the directory layout of my project. The extensions directory is where developers drop in their expanded functionality.

/root
    /extensions
        /extension1
            __init__.py
            extension1.py
        /extension2
            __init__.py
            extension2.py
    simple_example.py

The problem is that I get this error and am not sure what it is telling me.

>python simple_example.py
Traceback (most recent call last):
  File "simple_example.py", line 14, in <module>
    app.register_blueprint(loaded_mod)
  File "C:\Python27\lib\site-packages\flask\app.py", line 62, in wrapper_func
    return f(self, *args, **kwargs)
  File "C:\Python27\lib\site-packages\flask\app.py", line 880, in register_blueprint
    if blueprint.name in self.blueprints:
AttributeError: 'module' object has no attribute 'name'

A simple extension looks like this

from flask import Blueprint

extension1 = Blueprint('extension1', __name__)

@extension1.route("/my_route")
def treasure_list():
    return "list of objects"

How do I solve the AttributeError in a way that allows my app.register_blueprint call to succeed?

Answer 1

You are trying to register the module and not the contained Blueprint object.

You'll need to introspect the module to find Blueprint instances instead:

if mod_name not in sys.modules:
    loaded_mod = __import__(EXTENSIONS_DIR+"."+mod_name+"."+mod_name, fromlist=[mod_name])
    for obj in vars(loaded_mod).values():
        if isinstance(obj, Blueprint):
            app.register_blueprint(obj)