Python FastAPI Serializers and Controllers Lab Solution

About

This repo contains the solution code for the Python FastAPI Serializers and Controllers Lab

Getting Started

1. Fork and clone this repo.

2. Navigate into the project directory:

 cd python-fastapi-serializers-and-controllers-lab-solution

3. Install dependencies (this also creates the virtual environment if it doesn’t exist):

 pipenv install

4. Activate the virtual environment:

 pipenv shell

5. Set up your PostgreSQL database:

   • Ensure PostgreSQL is installed and running on your machine.
   • Create a database named teas_db if it does not already exist:

createdb teas_db

6. Open the application in Visual Studio Code:

code .

7. The database connection string is defined in the config/environment.py file:

db_URI = "postgresql://<username>@localhost:5432/teas_db"

Modify your database connection string to use your username as the <username>.

8. Seed the database with initial data:

   • Run the seed.py file to reset the database by dropping existing tables and repopulating it with starter data:

pipenv run python seed.py

You should see output indicating the database was successfully seeded. If there are any errors, check the db_URI in the config/environment.py file.

9. Start the development server:

pipenv run uvicorn main:app --reload

You should now have the app running. Visit http://127.0.0.1:8000 in your browser to confirm it’s working.

10. Now you can test each endpoint using FastAPI’s built-in documentation.

Navigate to FastAPI Documentation: Open http://localhost:8000/docs in your browser.

Troubleshooting PostgreSQL

• The database connection string is defined in the config/environment.py file:

  db_URI = "postgresql://<username>@localhost:5432/teas_db"

• Ensure your PostgreSQL instance is configured to allow connections with the provided credentials.

• Modify your database connection string to use your username as the <username>.

Setting Up a User in PostgreSQL

To connect to a specific PostgreSQL user, use the following command:

psql -U <username>

Handling "Role Does Not Exist" Error

If you see this error:

Error: FATAL: role "<username>" does not exist

it means that the specified user does not exist in PostgreSQL.

Creating a New PostgreSQL User

To create the user, run the following command inside psql:

CREATE ROLE "<username>" WITH LOGIN PASSWORD 'your_secure_password';

🔹 Replace <username> with your desired username and choose a secure password.

This will allow you to connect using one of the following database connection strings:

Connection Strings:

If no password is required:

db_URI = "postgresql://<username>@localhost:5432/teas_db"

If a password is required:

db_URI = "postgresql://<username>:<your_secure_password>@localhost:5432/teas_db"

This ensures that PostgreSQL correctly authenticates and allows access to the teas_db database.