Redirecting to URL in Flask

Question

I'm new to Python and Flask and I'm trying to do the equivalent of Response.redirect as in C# - ie: redirect to a specific URL - how do I go about this?

Here is my code:

import os
from flask import Flask

app = Flask(__name__)

@app.route('/')
def hello():
    return 'Hello World!'

if __name__ == '__main__':
    # Bind to PORT if defined, otherwise default to 5000.
    port = int(os.environ.get('PORT', 5000))
    app.run(host='0.0.0.0', port=port)

Solution 1

You have to return a redirect:

import os
from flask import Flask,redirect

app = Flask(__name__)

@app.route('/')
def hello():
    return redirect("http://www.example.com", code=302)

if __name__ == '__main__':
    # Bind to PORT if defined, otherwise default to 5000.
    port = int(os.environ.get('PORT', 5000))
    app.run(host='0.0.0.0', port=port)

See the documentation on flask docs. The default value for code is 302 so code=302 can be omitted or replaced by other redirect code (one in 301, 302, 303, 305, and 307).

Solution 2

#!/usr/bin/env python
# -*- coding: utf-8 -*-

import os
from flask import Flask, redirect, url_for

app = Flask(__name__)

@app.route('/')
def hello():
    return redirect(url_for('foo'))

@app.route('/foo')
def foo():
    return 'Hello Foo!'

if __name__ == '__main__':
    # Bind to PORT if defined, otherwise default to 5000.
    port = int(os.environ.get('PORT', 5000))
    app.run(host='0.0.0.0', port=port)

Take a look at the example in the documentation.

Solution 3

From the Flask API Documentation (v. 2.0.x):

flask.redirect(location, code=302, Response=None)

Returns a response object (a WSGI application) that, if called, redirects the client to the target location. Supported codes are 301, 302, 303, 305, and 307. 300 is not supported because it’s not a real redirect and 304 because it’s the answer for a request with a request with defined If-Modified-Since headers.

New in version 0.6: The location can now be a unicode string that is encoded using the iri_to_uri() function.

Parameters:

• location – the location the response should redirect to.
• code – the redirect status code. defaults to 302.
• Response (class) – a Response class to use when instantiating a response. The default is werkzeug.wrappers.Response if unspecified.

Solution 4

I believe that this question deserves an updated. Just compare with other approaches.

Here's how you do redirection (3xx) from one url to another in Flask (0.12.2):

#!/usr/bin/env python

from flask import Flask, redirect

app = Flask(__name__)

@app.route("/")
def index():
    return redirect('/you_were_redirected')

@app.route("/you_were_redirected")
def redirected():
    return "You were redirected. Congrats :)!"

if __name__ == "__main__":
    app.run(host="0.0.0.0",port=8000,debug=True)

For other official references, here.

Solution 5

Flask includes the redirect function for redirecting to any url. Futhermore, you can abort a request early with an error code with abort:

from flask import abort, Flask, redirect, url_for

app = Flask(__name__)

@app.route('/')
def hello():
    return redirect(url_for('hello'))

@app.route('/hello'):
def world:
    abort(401)

By default a black and white error page is shown for each error code.

The redirect method takes by default the code 302. A list for http status codes here.

View more solutions

Comments

[Sunvic]

note that you are passing the function name into url_for which then builds a URL which is passed to redirect and you return that.

[Rylan Schaeffer]

When I do this, my client hitting the endpoint receives a CORS error. Do you know an easy to get around this? I can find a lot of questions and a lot of answers, but not much clarity

[Xavier Combelle]

This is a different problem, can you ask your own question @RylanSchaeffer ?