Building a Secure Flask App with PostgreSQL: Connecting Storing and Testing User Data

Connecting Flask Application with PostgreSQL

Developing a Flask application that can store user information in a PostgreSQL database is an essential skill for any aspiring web developer. This article will cover the basics of connecting Flask Application with PostgreSQL using SQLAlchemy and how to code Flask Application to store user information in the database.

Part 1: Connecting Flask Application with PostgreSQL database using SQLAlchemy

PostgreSQL is a community-driven RDBMS that utilizes SQL to manage Table structures, records, and fields. It is an ORBDMS, which means it supports advanced data types such as JSON and XML.

When developing a Flask Application, we can use SQLAlchemy, a Python ORM, to connect our application with PostgreSQL. Before we move on to connecting Flask Application with PostgreSQL, let’s first understand the differences between MySQL and PostgreSQL.

While MySQL is a widely-used community-driven RDBMS, PostgreSQL is an ORDBMS, making it a more comprehensive database system. While MySQL is an excellent choice for small to medium-sized projects, PostgreSQL is better suited for larger projects that require advanced data types.

Now that we have a clear understanding of PostgreSQL, we can connect our Flask Application with the database using SQLAlchemy. We must first set up PostgreSQL in our system and obtain connection details.

We can then create models using SQLAlchemy, Flask-SQLAlchemy, and Flask-Migrate, which can map our Python Class objects with our PostgreSQL database tables. We can then create an InfoModel table to store user information.

This table will have columns for the user’s name, email, and password.

Part 2: Coding Flask Application to store user information in the database

Now that we’ve set up our connection, let’s move on to coding our Flask Application to store user information in the database.

We’ll first connect our Flask object to our PostgreSQL Connection using SQLAlchemy, SQLAlchemy object, and Migrate Object. We’ll then provide views that allow users to interact with our database by submitting user information.

When a user clicks on the submit button, our view will utilize the POST method to send a request to our Flask Application’s server. Our code will then retrieve the information submitted by the user and create a new_user instance.

The new_user instance will contain the information submitted by the user. We’ll then use the db.session.add() method on our new_user instance to save the user’s information to our InfoModel table.

Finally, we’ll utilize the db.session.commit() method to finalize the storage of the user’s information to our database.

Running Migrations and Testing the Application

In the previous section, we discussed how to connect our Flask Application to PostgreSQL and store user information in the database. This section will delve deeper into implementing the Flask code and running migrations to make changes to the database. We will also discuss how to test our Flask Application and check the results in the PostgreSQL shell.

Part 1: Running migrations to make changes to the database

After we have set up our Flask Application and connected it to our PostgreSQL database, we can make changes to the database’s structure by running migrations. We can create a migration repository by using the following command:

flask db init

Once we have created the migration repository, we can create our first migration by using the following command:

flask db migrate -m "create user table"

This command will create a migration script that we can use to make changes to our database structure. We can then apply the migration to our database by using the following command:

flask db upgrade

This command will apply the migration to our database, adding or modifying tables as needed. The upgrade command will also be used to apply any additional migrations created in the future.

Part 2: Testing the Flask Application and checking results in the PostgreSQL shell

After we have implemented our Flask Application and made changes to our database structure, we need to test our application to ensure that it works correctly. We can do this by using a browser to interact with our application, submitting user information through the form.

Once we have collected some user information in our database, we can check the results by accessing the PostgreSQL shell. We can use the SELECT statement to retrieve the user information from the InfoModel table:

SELECT * FROM InfoModel;

This command will return a list of all the users and their information stored in the InfoModel table.

We can use this information to verify that our Flask Application is successfully storing and retrieving user information.

Conclusion

In conclusion, we have discussed how to run migrations to make changes to our database structure and test our Flask Application to ensure that it is functioning correctly. The ability to run migrations and test an application is crucial for ensuring proper functionality and security.

With these skills, developers can build Flask Applications that are efficient, secure, and reliable, ensuring user satisfaction and organizational success.