![]() ![]() A common pattern in database design for transactional systems of this type are to break the orders into two additional tables, orders and line items (sometimes referred to as order details) to achieve greater normalization. Upon inspecting this data it is evident that it contains information about customers, products, and orders. However, to aid in our discussion of SQLite database programming with Python I will be working off the premise that a database needs to be created for a fictitious book store that has the below data already collected on book sales. I will not be going into the details of this practice and will instead leave it up to reader to further investigate. There are many design considerations that go into defining the tables of a relational database, which entire books have been written about. In order to create database tables you need to have an idea of the structure of the data you are interested in storing. # create a default path to connect to and create (if necessary) a database # called 'database.sqlite3' in the same directory as this scriptĭEFAULT_PATH = os.path.join(os.path.dirname(_file_), 'database.sqlite3') You will find that in everyday database programming you will be constantly creating connections to your database, so it is a good idea to wrap this simple connection statement into a reusable generalized function. import sqlite3Ĭon = nnect( '/path/to/file/db.sqlite3') To establish a connection all you need to do is pass a file path to the connect(.) method in the sqlite3 module, and if the database represented by the file does not exists one will be created at that path. Creating a Database and Making a ConnectionĬreating a new SQLite database is as simple as creating a connection using the sqlite3 module in the Python standard library. However, it is not uncommon to hear it being used for small to medium web and desktop applications. SQLite is often the technology of choice for small applications, particularly those of embedded systems and devices like phones and tablets, smart appliances, and instruments. SQLite is a single file relational database bundled with most standard Python installs. Now the webapp should also show the list of logged users.This tutorial will cover using SQLite in combination with Python's sqlite3 interface. If you complete and submit the form, the results will be also reflected in the terminal (pay attention at the POST method): * Running on (Press CTRL+C to quit)ġ27.0.0.1 - "POST / HTTP/1.1" 200. Open your browser and visit 0.0.0.0:5000 (or 127.0.0.1:5000), the html will render and show up the login form. Output : * Running on (Press CTRL+C to quit) To run the Flask app (server) type into your terminal: python main.py All together: Testing and explaining data's flow Note: The host parameter can be changed to 127.0.0.1 (localhost) instead of 0.0.0.0. ![]() The Database Handler (models.py) methods are called when main.py has to acces and/or modify the database: dbHandler.insertUser(username, password), users = dbHandler.retrieveUsers(). This app makes database calls in order to insert new users and to return the logged users list requested by the POST method. Return render_template( 'index.html', users = users)Īpp. route( '/', methods =) def home():ĭbHandler. In the case of a POST request (created after the form submission) it returns the list of logged users.įrom flask import Flask from flask import render_template from flask import request import models as dbHandler app = Flask( app. If the HTTP request is GET, the app returns the HTML form. This application works with a single flask function/route/url (views for convention) which answers to two types of HTTP methods (GET, POST). Flask Appįlask is a python microframework intended for the developement of web applications (server side). The html contains a simple html form with two text type inputs: username and password, and a submit type input (Login button). ![]() ![]() It uses the Flask template engine to render the 'logged users' list. The html code used for this app can be found in index.html file (in this same git). We'll later call these methods from main.py to handle the database. execute( "SELECT username, password FROM users") execute( "INSERT INTO users (username,password) VALUES (?,?)", ( username, password))Ĭur. Import sqlite3 as sql def insertUser( username, password):Ĭur. ![]()
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