redirect while passing arguments

Question

In flask, I can do this:

render_template(\"foo.html\", messages={\'main\':\'hello\'})

And if foo.html contains {{ messages[\'main\']

Answer 1

You could pass the messages as explicit URL parameter (appropriately encoded), or store the messages into session (cookie) variable before redirecting and then get the variable before rendering the template. For example:

def do_baz():
    messages = json.dumps({"main":"Condition failed on page baz"})
    session['messages'] = messages
    return redirect(url_for('.do_foo', messages=messages))

@app.route('/foo')
def do_foo():
    messages = request.args['messages']  # counterpart for url_for()
    messages = session['messages']       # counterpart for session
    return render_template("foo.html", messages=json.loads(messages))

(encoding the session variable might not be necessary, flask may be handling it for you, but can't recall the details)

Or you could probably just use Flask Message Flashing if you just need to show simple messages.