Flask register_blueprint error (Python)

I just ran into this same issue with another application that I was refactoring to use blueprints. There's no need for a workaround, since Flask offers a decorator for just such a case: app_errorhandler. It works exactly like errorhandler in that it registers an error route for the entire app, but it works with blueprints. Like so:

from flask import render_templatefrom . import main @main.app_errorhandler(404)def page_not_found(e):    return render_template('404.html'), 404@main.app_errorhandler(500)def internal_server_error(e):    return render_template('500.html'), 500

Grinberg's book, Flask Web Development -- an excellent read -- uses this decorator for error pages registered on the main blueprint. You can review the companion code here. I missed it at first, too. :P

You can't create a 500 handler on a blueprint.

https://www.bountysource.com/issues/1400879-can-not-register-a-500-error-handler-for-blueprint

You'll have to do it on the main application. I feel your pain though, since you have an app factory and no routes in app/__init__.py.

I usually do something like this in my app factory modules to handle this shortcoming:

def register_errorhandlers(app):    def render_error(error):        error_code = getattr(error, 'code', 500)        return render_template("{0}.html".format(error_code)), error_code    for errcode in [500]:        app.errorhandler(errcode)(render_error)    return None

and in create_app(config_name), app factory method, I call it:

register_errorhandlers(app)