Flask decorator : Can't pass a parameter from URL

You defined group_id as a function parameter; that makes it a local name in that function.

That doesn't make the name available to other scopes; the global namespace that the decorator lives in cannot see that name.

The wrapper function, however, can. It'll be passed that parameter from the @apps.route() wrapper when called:

def group_required(func):    @wraps(func)    def wrapper(group_id, *args, **kwargs):        #Core_usergroup : table to match users and groups        groups = Core_usergroup.query.filter_by(user_id = g.user.id).all()        for group in groups:            #if the current user is in the group : return func            if int(group.group_id) == int(group_id) :                return func(*args, **kwargs)        flash(gettext('You have no right on this group'))        return render_template('access_denied.html')         return wrapper

Note that this decorator doesn’t bother with passing on the group_id parameter to the decorated function; use return func(group_id, *args, **kwargs) instead of you still need access to that value in the view function.