烧瓶会话变量在请求后不会更改

Question

I want to update the variable('CAPTCHA_NUM') when I visit the url('/captcha') and get this variable in templates:

@app.route('/captcha')
def captcha():
    from captcha.image import ImageCaptcha
    from random import random
    image = ImageCaptcha()
    x = int(round(random() * 10000))
    if x < 1000: x += 1000
    session['CAPTCHA_NUM'] = x
    return image.generate(str(session['CAPTCHA_NUM']), 'png').getvalue()

But each time when I refresh my page(visit this url), the captcha updates, however the session['CAPTCHA_NUM'] doesn't.

For example, first I get the captcha 7530 , then I refresh register.html (which visits the url) and captcha is updated but the session['CAPTCHA_NUM'] still is 7530 .

And this is where I visit the url(captcha):

register.html

<img id="vcode" src="{{url_for('captcha')}}" alt="captcha" />

and I get session['CAPTCHA_NUM'] in validate_capcha() :

<input type="text" name="captcha" onblur="validate_captcha()" />

=================Solution========================

In the official doc of flask session , it says:

This variable is unavailable if the template was rendered without an active request context.

I just change the src attribute of img tag, and apparently this isn't an active request context.

And finally I put the captcha validation part at the server-side so that I can avoid this problem.

Answer 1

if you use visit http://***.com/captcha it won't refresh. you Need to give it a param so it will refresh

at first you write

url_for('.captcha')

change it to

url_for('.captcha',t=some_random_value)

then it will refresh cause it generate a url like this: http://***.com/captcha?t=some_random_value