Post output from user input on same web page using HTML and Flask (python)

I'm trying to post output on a web page based on user input using HTML and Flask. Given below are the codes.

app.py :

import pandas as pd
from flask import Flask, render_template, request

app = Flask(__name__)



@app.route('/', methods=['GET', 'POST'])
def predict():

        if request.method == 'POST':
                x_in = request.form.get('x_in')
        elif request.method == 'GET':
                data = pd.DataFrame({'data':[int(x_in)*10]})
                return render_template('index.html', data=data.to_html())


if __name__ == '__main__':

        app.run(host='0.0.0.0', port=80, debug=False)

I have used the following 2 html files for rendering.

template.html:

html lang="en" dir="ltr">
  <head>
    <meta charset="utf-8">
    <title>Flask Parent Template</title>
  </head>
  <body>
    <header>
      <div class="container">
        <h1 class="logo">Trial</h1>
        <strong><nav>
            <ul class="menu">
              <li><a href="{{ url_for('predict') }}">Home</a></li>
            </ul>
          </nav></strong>
        </div>
      </header>

      {% block content %}
      {% endblock %}

    </body>
  </html>

index.html:

html>
  <title>About the App</title>
  <head>
  <body>
    {% extends "template.html" %}
    {% block content %}

    <form action = / method="POST">
      <label for="x_in">INPUT:</label>
      <input type="text" name="x_in" id="x_in" size="15">
      <input type="submit" value="Generate Result" />
    </form>
        {{data|safe}}
    {% endblock %}
  </body>
</html>

However, I am getting an error as follows : UnboundLocalError: local variable 'x_in' referenced before assignment

This is a very simple code and I am not sure why the 'POST' method isn't receiving the input from user. My guess is it's a trivial error but any help would be appreciated.

Solution

According to me you want to show a input form and user enter imput and get result

@app.route('/', methods=['GET', 'POST'])
def predict():
      if request.method == 'POST':
           x_in = request.form.get('x_in')
           data = pd.DataFrame({'data':[int(x_in)*10]})
           return render_template('index.html', data=data.to_html())
      return render_template("index.html")

in jinja do this

{% if data %}
{{data|safe}}
{% endif %}