Python Flask, Jinja Global

Question

I am currently using Python Flask and Jinja2. I have a table with some message. I want to basically have a button on the menu with the number of messages that a user has.

I've used this to make my sidebar global so it can appear on multiple pages: app.jinja_env.globals.update(...)

This is the code I've used to get the number of messages: def message_notification(): c.execute("SELECT count(*) FROM messages WHERE read = 0 AND receiver = ?",(session['username'],)) msgnotifcation = c.fetchone() return msgnotifcation[0]

However I am getting this error: RuntimeError: Working outside of request context.

Is there any other way to do this as I figured out that the problem is to do with the session['username'] bit.

Answer 1

You need to move this code so that it executes before the template starts to render, ie it will be inside the request context.

Flask provides the context_processor decorator to achieve this. http://flask.pocoo.org/docs/0.12/templating/#context-processors The values returned will be available in all your templates as though they had been returned as any other context item from a view.

@app.context_processor
def message_count():
    value = ...your sql...
    return dict(message_count=value)

Then in your views you can use:

{{ message_count }}