How to prevent data from disappearing when refreshing web page?

Question

In app.py I established a connection with my database then retrieved the data and stored it in a cursor object. I want to show the data on a web page so I transferred it with :

render_template('home.html', data=cursor)

Which works, it shows the data on my web page but when I refresh the page I get :

GET http://127.0.0.1:5000/static/css/template.css net::ERR_ABORTED 404 (NOT FOUND)

and my data doesn’t show anymore.

app.py :

from flask import Flask, render_template
import sqlite3
import os.path

app = Flask(__name__)
BASE_DIR = os.path.dirname(os.path.abspath(__file__))
db_path = os.path.join(BASE_DIR, "movies.db")
with sqlite3.connect(db_path, check_same_thread=False) as db:
#I used check_same_thread=False to solve a same thread error 
     cursor = db.cursor()
     cursor.execute("SELECT * FROM data")

@app.route("/")
def home():

   return render_template('home.html', data=cursor)

if __name__== "__main__":
    app.run(debug=True)

A piece of home.html :

<body>
    {% extends "template.html" %}
    {% block content %}
    {% for item in data %}
    <tr>
        <td><a>{{item[1]}}</a></td>
    </tr>
    {% endfor %}
    {% endblock %}
  </body>

I want my web page to show the data without disappearing when I refresh my page.

Asked By: imkeVr

||

Source

Answer 1

Try moving all code related to connecting and making a request inside a request handler function (home()). Also, official documentation may give you a hint on a proper implementation.

Answered By: Fine

Answer 2

According to the official documentation as @Fian suggested, you need to open the database connection on demand and close them when the context dies.

Updated code for app.py:

import os
import sqlite3
from flask import Flask, render_template, g

app = Flask(__name__)
BASE_DIR = os.path.dirname(os.path.abspath(__file__))
DATABASE = os.path.join(BASE_DIR, "movies.db")

def get_db():
    db = getattr(g, '_database', None)
    if db is None:
        db = g._database = sqlite3.connect(DATABASE)
    return db

@app.teardown_appcontext
def close_connection(exception):
    db = getattr(g, '_dattabase', None)
    if db is not None:
        db.close()

@app.route('/')
def index():
    cur = get_db().cursor()
    cur.execute('SELECT * FROM data')
    rows = cur.fetchall()
    return render_template('index.html', rows = rows)

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

index.html:

<html>
    <head>
        <title>SQLite in Flask</title>
    </head>
    <body>
        <h1>Movies</h1>
        {% if rows %}
            <ul>                
            {% for row in rows %}
                <li>{{ row[0] }}</li>
            {% endfor %}
            </ul>
        {% endif %}
    </body>
</html>

Output:

Reference:

Using SQLite 3 with Flask – Official documentation

Answered By: arsho

How to prevent data from disappearing when refreshing web page?

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