How to change the variable by input given by the template engine?

Question

Jinja

I pass a variable to html in this way using Jinja:

<h3>Себестоимость продаж: {{data.cost_of_sales}} </h3>

You need the ability to change its values ​​by entering it in a text field, how can this be done? Code welcome

Answer 1

<form action="адрес обработчика" method="post">
  <input type="text" name="cost" value="{{data.cost_of_sales}}">
</form>

And of course you need to write a form handler.