Flask: Render a dynamic template by clicking HTML button

Let's say I have in a view this html code

<html>
stuff...
{% if thisistrue %}
<p> let me see this </p>
{% endif %}
</html>

I'd like to have thisistrue = True only if I press a button from another view. Otherwise I want it to false.

I tried to use dynamic flask routes and jquery like

@app.route('/mainroute/<param/')
def main(param):
if param:
 return render_template(thisistrue = True)
else:
 return render_template(thisistrue = False)

but I failed since it doesn't fit with my subroutes (like mainroutes/somethingelse/

Solution

Use javascript with onclick event (for button) whose href value leads to new_template.html. The content of the new_template.html will be rendered by the python file.

Edit: The same thing can be done without javascript as well (i.e) using <button href = "/new-template">Submit</button>. But here full page reload will take place and the transition will not be smoother. For the sake of good user experience, the javascript is important.

Edit-2: Since there was an error again, edited now. Since the variable show_data is passed as an argument along with the url(which is similar to the get request), If we declare just show_data= True, It won't work. Instead, it should be show_data = request.args.get('showData', True)`. Now it is working alright.

Please no that there is a difference in spelling and case between 'showData' in javascript and show_data in the python script

HTML with button(index.html)

<!DOCTYPE html>
<html>
<head>
    
</head>
<body>
    
    <button id="new_temp">Submit</button>

    <script>
        document.getElementById("new_temp").addEventListener("click", function() {
            window.location.href = "/new_template?showData=true";
        });
    </script>
</body>
</html>

Python

from flask import Flask as fl, request as rq
from flask import render_template as tmp

app = fl(__name__)

@app.route("/")
def index(): return tmp("index.html")

@app.route("/new_template")
def new_template():
    show_data = rq.args.get("showData", True)   
    txt = "This is the new template content!"  
    return tmp("new_template.html", data=txt, show_data=show_data)

if __name__ == '__main__': app.run()

HTML (new_template.html):

<!DOCTYPE html>
<html>
<head>
</head>
<body>
    {% if show_data %}
        <h1>{{ data }}</h1>
    {% endif %}
</body>
</html>