Python redirect (with delay)

Question

So I have this python page running on flask. It works fine until I want to have a redirect.

@app.route("/last_visit")
def check_last_watered():
    templateData = template(text = water.get_last_watered())
    return render_template('main.html', **templateData)
    return redirect(url_for('new_page')) #with a delay here of 3 secs

The site works fine, but does not redirect and I wouldn't know how to delay the whole thing. Ideas... Please :-)

You can't return twice from a function and can't tell a browser to render a page then redirect. Either return a page which redirects using Javascript or return an HTTP redirect. (You should probably understand what the `redirect` method actually does) — Alastair McCormack, Nov 15 '18 at 13:12
ok, well ... after two seconds the page should forward to another page. — Sabrina Tesla, Nov 15 '18 at 13:21

dmitrybelyakov · Answer 1 · 2021-07-15T10:33:45.587

5

Well, your function just returns a rendered template and never reaches the redirect statement. If you want to show a page AND then do a redirect after a delay, use a javascript redirect in your template:

@app.route("/last_visit")
def check_last_watered():
    templateData = template(text = water.get_last_watered())
    templateData['redirect_url'] = url_for('new_page')
    return render_template('main.html', **templateData)

Then in your main.html:

<script>
    setTimeout(function(){
        window.location.href = '{{redirect_url}}';
    }, 2000);
</script>

UPDATE: Also, have a look at an alternative (and possibly better) way by Adrián, where you can return a Refresh header along with your rendered template response.

edited Jul 15 '21 at 10:33

answered Nov 15 '18 at 13:09

dmitrybelyakov

3,709
2
22
26

Thanks. So I am trying this: @app.route("/last_visit") def check_last_watered(): templateData = template(text = water.get_last_watered()) return render_template('main.html', **templateData['main.html'] = url_for('new_page')) with the javascript in the main.html but flask crashes – Sabrina Tesla Nov 15 '18 at 13:17
@SabrinaTesla I have updated my answer to include your flask view in its entirety – dmitrybelyakov Nov 15 '18 at 13:23
Thank you. the site is now reloading every 2000ms in every case, not just for @app.route("/last_visit") – Sabrina Tesla Nov 15 '18 at 15:15
I am also getting this error: BuildError: Could not build url for endpoint 'new_page'. – Sabrina Tesla Nov 15 '18 at 15:19
1

Please read up on flask a little. A good point to start is the quickstart guide: http://flask.pocoo.org/docs/1.0/quickstart/ – dmitrybelyakov Nov 15 '18 at 15:58

score 5 · Answer 2 · answered Sep 17 '20 at 16:13

5

If you need to render a template and redirect after three seconds you can pass refresh as time and url with the URL you need to redirect.

@app.route('/error/', methods=['GET'])
def error():
    return render_template('error.html'), {"Refresh": "1; url=https://google.com"}

answered Sep 17 '20 at 16:13

Adrian

380
3
13

1

Oh, that's a nice one! Thanks, @Adrián – dmitrybelyakov Jul 15 '21 at 10:31
2

this is much more better than putting stupid setTimeout in javascript – alexzander Dec 12 '21 at 16:36

blkpingu · Answer 3 · 2019-08-06T11:47:36.690

You could use a return statement and return a string format.

As the <redirect url> you could set any URL from available to your back-end.

This solution is similar to dmitrybelyakov's, but it's a quick fix without having to deal with new, small html templates.

return f"<html><body><p>You will be redirected in 3 seconds</p><script>var timer = setTimeout(function() {{window.location='{ <redirect url> }'}}, 3000);</script></body></html>"

Example:

Lets say you want to submit a form and have a run time issue that requires you to do this redirect after a certain time.

@app.route('/')
def your_func():
  form = FormFunc()

  if form.validate_on_submit():
    # do something
    wait_time = 3000
    seconds = wait_time / 1000
    redirect_url = 'https://www.example.com/'

    # if the validation is successful, forward to redirect page, wait 3 seconds, redirect to specified url
    return f"<html><body><p>You will be redirected in { seconds } seconds</p><script>var timer = setTimeout(function() {{window.location='{ redirect url }'}}, { wait_time });</script></body></html>"

# if the validation is not successful, reload the form
return render_template('formPage.html', form=form)

Python redirect (with delay)

3 Answers3

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