You should try running the Flask app in debug mode:
app.run(host='127.0.0.1', port=5000, debug=True)
That will give you a more detailed error message:
werkzeug.exceptions.BadRequestKeyError: 400 Bad Request: The browser (or proxy) sent a request that this server could not understand.
KeyError: 'number'
This indicates that there is no form item with the name number in the submitted form. Looking at your HTML form, it looks like the name attribute has been misplaced; you also need it in the select element. This HTML form fixes the error:
<form action="#" method="POST">
<select name="number">
{% for i in range(length) %}
<option name="number">change number {{d[i]}}</option>
{% endfor %}
</select>
<input type="submit">
</form>
I try to use select method in html with flask. My code is
from flask import Flask, render_template, request
import psycopg2
import numpy as np
d = [10,12,16,17]
@app.route('/demo_html', methods=['GET', 'POST'])
def process_number():
selected_number = ''
if request.method == 'POST':
selected_number = request.form['number']
return render_template('demo_html.html', d=d, length=len(d),selected_number=selected_number)
This is my html file
demo_html
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<title>Title</title>
</head>
<body>
<form action="" method="POST">
<select>
{% for i in range(length) %}
<option name="number">change number {{d[i]}}</option>
{% endfor %}
</select>
<input type="submit">
</form>
<p>you selected number {{ selected_number }}</p>
</body>
</html>
At the second step I get the following error: Bad Request
The browser (or proxy) sent a request that this server could not understand.
The question: How do I render the template successfully using the post method?
shouldnt the form action be something like this: form action=”{{ url_for(‘process_number’) }}”
