Book Image

Web App Development Made Simple with Streamlit

By : Rosario Moscato
Book Image

Web App Development Made Simple with Streamlit

By: Rosario Moscato

Overview of this book

This book is a comprehensive guide to the Streamlit open-source Python library and simplifying the process of creating web applications. Through hands-on guidance and realistic examples, you’ll progress from crafting simple to sophisticated web applications from scratch. This book covers everything from understanding Streamlit's central principles, modules, basic features, and widgets to advanced skills such as dealing with databases, hashes, sessions, and multipages. Starting with fundamental concepts like operation systems virtualization, IDEs, development environments, widgets, scripting, and the anatomy of web apps, the initial chapters set the groundwork. You’ll then apply this knowledge to develop some real web apps, gradually advancing to more complex apps, incorporating features like natural language processing (NLP), computer vision, dashboards with interactive charts, file uploading, and much more. The book concludes by delving into the implementation of advanced skills and deployment techniques. By the end of this book, you’ll have transformed into a proficient developer, equipped with advanced skills for handling databases, implementing secure login processes, managing session states, creating multipage applications, and seamlessly deploying them on the cloud.
Table of Contents (23 chapters)
Free Chapter
1
Part 1: Getting Started with Streamlit
5
Part 2: Building a Basic Web App for Essential Streamlit Skills
10
Part 3: Developing Advanced Skills with a Covid-19 Detection Tool
15
Part 4: Advanced Techniques for Secure and Customizable Web Applications

Connecting to a relational database and interacting with it

As explained in the Understanding the logic behind the login and signup page section, we want to save the accounts in a database. So, we have to import the database libraries. As mentioned previously, we are using a SQLite3 database. So, first of all, let’s install its Python library by typing the following:

pipenv install sqlite3

Then, simply import the library by writing import sqlite3 in our app.py file.

Making a SQLite3 database work for us is a quite simple task. For this, we need to open a connection to the database by specifying its name (in our case, userdata.db) as an argument and creating a cursor to execute operations in it.

On lines 6 and 7 in Figure 13.4, the connection and cursor are created:

Figure 13.4: The connection to the database and its cursor

Figure 13.4: The connection to the database and its cursor

To recap, the connection (conn) opens a connection to the database while the cursor (c) makes it possible to operate...