下面是我想以Json形式而不是HTML形式返回數據的代碼

這是我的第一個文件app.py

from flask import Flask, render_template, request, redirect, url_for,flash
import psycopg2 
import psycopg2.extras

app=Flask(__name__, template_folder='templates')
app.secret_key = "cairocoders-ednalan"
 
DB_HOST = "localhost"
DB_NAME = "sampledb"
DB_USER = "postgres"
DB_PASS = "1122"
 
conn = psycopg2.connect(dbname=DB_NAME, user=DB_USER, password=DB_PASS, host=DB_HOST)

@app.route('/')
def Index():
    cur = conn.cursor(cursor_factory=psycopg2.extras.DictCursor)
    s = "SELECT * FROM students"
    cur.execute(s)
    list_users = cur.fetchall()
    return render_template('index.html', list_users = list_users)
@app.route('/add_student', methods=['POST'])
def add_student():
    cur = conn.cursor(cursor_factory=psycopg2.extras.DictCursor)
    if request.method == 'POST':
        fname = request.form['fname']
        lname = request.form['lname']
        email = request.form['email']
        cur.execute("INSERT INTO students (fname, lname, email) VALUES (%s,%s,%s)", (fname, lname, email))
        conn.commit()
        flash('Student Added successfully')
        return redirect(url_for('Index'))
if __name__ == '__main__':
    app.run(debug=True)

我想以JSON格式而不是HTML格式返回我的數據

這是HTML格式文件index.html

{% extends "layout.html" %}
{% block body%}
<div class="row"><h3>Students</h3></div>
 <div class="row">
    <div class="col-md-4">
        {% with messages = get_flashed_messages()  %}
        {% if messages %}
        {% for message in messages %}
        <div class="alert alert-success alert-dismissible fade show" role="alert">
            {{ message }}
            <button type="button" class="close" data-dismiss="alert" aria-label="Close">
                <span aria-hidden="true">×</span>
            </button>
        </div>
        {% endfor %}
        {% endif %}
        {% endwith %}
        <form action="{{url_for('add_student')}}" method="POST">
            <div class="form-group">
              <input type="text" class="form-control" name="fname" placeholder="First Name">
            </div>
            <div class="form-group">
              <input type="text" class="form-control" name="lname" placeholder="Last Name">
            </div>
            <div class="form-group">
              <input type="email" class="form-control" name="email" placeholder="Email">
            </div>
            <button class="btn btn-primary btn-block">
              Save 
            </button>
          </form>
    </div>
    <div class="col-md-8">
        <table class="table table-striped table-bordered" style="width:100%">
          <thead>
            <tr>
                <td>ID</td>
                <td>First Name</td>
                <td>Last Name</td>
                <td>Email</td>
            </tr>
          </thead>
          <tbody>
            {% for row in list_users %}
            <tr width="130">
                <td>{{row[0]}}</td>
                <td>{{row[1]}}</td>
                <td>{{row[2]}}</td>
                <td>{{row[3]}}</td>
                </td>
            </tr>
            {% endfor %}
          </tbody>
        </table>
    </div>
 </div>
{% endblock %}

所以問題是它以HTML格式返回數據，而我想以JSON格式返回數據 所以請幫我糾正我的代碼