How to use flask variables from outside the function to later use in javascript?

Question

Running routes.py

@app.route('/articles', methods=['GET', 'POST'])
def articles():
    upload()
    return render_template('articles.html')

And this function that saves an image and processes its information

def upload():
    if request.method == 'POST':
        # Save the file to static/uploads
    
        label = "some string from process above"
        probability = "another string"

        return None

    return None

How do I make use of the variables label and probability in rendering the template? Some people use something close to:

return render_template('articles.html', label=label, probability=probability)

This would be done to make a reference to variables using js. But how do I make a reference to that variable if it is computed inside of upload()? Any need for global variables?

if i return them like return label, probability will I be able to use them directly somewhere else or i should instead define label, probability = upload() ? — iustin
– iustin, Commented Jul 7, 2020 at 21:43
You have to unpack the variable you are sending from function, so first, you have to return them from upload and then unpack it to send it to render_template. — ParthS007
– ParthS007, Commented Jul 7, 2020 at 21:47

ParthS007 · Accepted Answer · 2020-07-07 21:49:36Z

2

You can return those variables from the function.

You have to unpack the variable you are sending from upload function.

First, you have to return them from upload and then unpack it to send it to render_template.

@app.route('/articles', methods=['GET', 'POST'])
def articles():
    label, probability = upload()
    return render_template('articles.html', label=label, probability=probability)

def upload():
    if request.method == 'POST':
        # Save the file to static/uploads
    
        label = "some string from process above"
        probability = "another string"

        return (label, probability)

    return (None, None)

edited Jul 7, 2020 at 21:49

answered Jul 7, 2020 at 21:44

ParthS007

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4 Comments

iustin Over a year ago

Thanks, now html/javascript id for each will be the names specified in render_template() right?

ParthS007 Over a year ago

I am not sure about what is id here?

iustin Over a year ago

For example, it will be easy to use <h3 id="label"></h3> and have the text in label be displayed?

ParthS007 Over a year ago

Yes, you can certainly do that by using something like this {{ label }}

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