Calling a Python function from HTML is not working

Question

In my HTML page, I have a button. When I click on the button it should call a Python function that takes a screenshot and save it in the same directory. I tried my Python method and it is working correctly on local. But when I used Flask to call the function from a HTML button, it does nothing and there are no errors. How to get the screenshot image ?

Python Flask:
@app.route('/')
def index():
    return render_template('index.html')

# Function to take the screenshot and save it
def takesc():
    with mss() as sct:
        sct.shot()

@app.route('/takeScreenshot')
def takeScreenshot():
    return takesc()

My HTML

<button onclick="{{ takeScreenshot }}">ScreenShoot</button>

I also tried to use 'url_for' as following, but still nothing happened:

<button onclick="{{ url_for('takeScreenshot') }}">ScreenShoot</button>

Ajax1234 · Accepted Answer · 2018-02-24 18:37:31Z

3

Instead of a button, it is shorter use an href:

<a href='/takeScreenshot' class='my_button_class'>ScreenShoot</a>

You can then use css to add style under the .my_button_class class.

However, to use a button, you need to specify the redirect:

<button type="button" onclick="window.location.href='{{url_for( 'takeScreenshot') }}';">Display Table Y</button>

Also, takeScreenshot is not returning text to be rendered on the screen. takesc does not return anything, thus, it should be called before the route returns a response:

@app.route('/takeScreenshot')
def takeScreenshot():
   takesc()
   return "screen shot saved"

edited Feb 24, 2018 at 18:37

answered Feb 24, 2018 at 18:26

Ajax1234

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2 Comments

codeDojo Over a year ago

Thank you so much, it worked. If you do not mind would you please tell me why I cannot use a button or what is the difference ? Also after clicking the link, the screenshot is taken but the execution ends and gives me this error 'ValueError: View function did not return a response'

codeDojo Over a year ago

Thank you so much, you are a life saver! Instead of returning "Screenshot saved" I return render("index.html") so that it does not take me to another page. Thanks again man!!!

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