FastAPI installation and setup - Mini Project: Build & Apply

FastAPI installation and setup

📖 Scenario: You want to create a simple web API using FastAPI, a modern Python web framework. Before writing any code, you need to install FastAPI and set up a basic application file.

🎯 Goal: Install FastAPI and create a minimal FastAPI app file that can run a web server.

📋 What You'll Learn

Install FastAPI using pip

Install an ASGI server called 'uvicorn' to run the app

Create a Python file named main.py

In main.py, create a FastAPI app instance

💡 Why This Matters

🌍 Real World

FastAPI is used to build fast and efficient web APIs for real-world applications like data services, web backends, and microservices.

💼 Career

Knowing how to install and set up FastAPI is essential for backend developers working with modern Python web frameworks.

1

Install FastAPI package

Use the command pip install fastapi in your terminal or command prompt to install the FastAPI package.

FastAPI

# Install the FastAPI package using pip
# Your code here

Hint

Open your terminal and type exactly pip install fastapi to install the package.

2

Install Uvicorn ASGI server

Use the command pip install uvicorn in your terminal to install Uvicorn, which will run your FastAPI app.

FastAPI

# Run the command 'pip install uvicorn' in your terminal

Hint

Uvicorn is a lightweight server for FastAPI. Install it by typing pip install uvicorn.

3

Create FastAPI app instance

In a new file named main.py, write the code to import FastAPI from fastapi and create an app instance called app with app = FastAPI().

FastAPI

# Create a file named main.py
# Write 'from fastapi import FastAPI' and 'app = FastAPI()' inside it
# Your code here

Hint

Open main.py and type exactly from fastapi import FastAPI and then app = FastAPI().

4

Run the FastAPI app with Uvicorn

Run the command uvicorn main:app --reload in your terminal to start the FastAPI server with auto-reload enabled.

FastAPI

# Run the command 'uvicorn main:app --reload' in your terminal

Hint

Start your server by typing exactly uvicorn main:app --reload in your terminal.

Practice

1. What is the main command to install FastAPI with all optional dependencies for full functionality?

easy

A. pip install fastapi[all]

B. pip install fastapi-core

C. pip install fastapi-full

D. pip install fastapi-basic

Solution

1. Step 1: Understand FastAPI installation options

   FastAPI can be installed with or without optional dependencies. The command with [all] installs everything needed for full features.

2. Step 2: Identify the correct pip command

   The correct command to install FastAPI with all optional dependencies is pip install fastapi[all].

3. Final Answer:

   pip install fastapi[all] -> Option A

4. Quick Check:

   Full install command = pip install fastapi[all] [OK]

Hint: Remember: [all] installs everything FastAPI needs [OK]

Common Mistakes:

• Using pip install fastapi without [all] misses optional tools
• Trying pip install fastapi-core which doesn't exist
• Confusing with pip install fastapi-full or fastapi-basic

2. Which command correctly runs a FastAPI app locally using Uvicorn?

easy

A. uvicorn app:app --reload

B. fastapi run app.py

C. python app.py

D. uvicorn run app.py

Solution

1. Step 1: Identify the tool to run FastAPI apps

   Uvicorn is the ASGI server used to run FastAPI apps locally for testing.

2. Step 2: Use the correct command syntax

   The correct command is uvicorn app:app --reload, where the first 'app' is the Python file name (without .py) and the second 'app' is the FastAPI instance.

3. Final Answer:

   uvicorn app:app --reload -> Option A

4. Quick Check:

   Run FastAPI with uvicorn app:app --reload [OK]

Hint: Use uvicorn with file:instance and --reload for dev [OK]

Common Mistakes:

• Trying to run FastAPI with python app.py directly
• Using wrong uvicorn syntax like 'uvicorn run app.py'
• Confusing fastapi run command which does not exist

3. Given this command run in terminal: uvicorn main:app --reload, what does the --reload flag do?

medium

A. Disables debugging features

B. Automatically restarts the server on code changes

C. Runs the server in production mode

D. Compiles the app to bytecode

Solution

1. Step 1: Understand the purpose of --reload flag

   The --reload flag tells Uvicorn to watch for code changes and restart the server automatically.

2. Step 2: Identify what happens without --reload

   Without --reload, the server runs but does not restart on code edits, making development slower.

3. Final Answer:

   Automatically restarts the server on code changes -> Option B

4. Quick Check:

   --reload means auto restart on code change [OK]

Hint: Reload flag = auto restart server on code edits [OK]

Common Mistakes:

• Thinking --reload enables production mode
• Assuming it disables debugging
• Believing it compiles code instead of reloading

4. You run uvicorn app:app --reload but get an error: ModuleNotFoundError: No module named 'app'. What is the likely cause?

medium

A. Uvicorn is not installed

B. The FastAPI instance is not named 'app' inside the file

C. The Python file named app.py does not exist in the current directory

D. The --reload flag is incompatible with your Python version

Solution

1. Step 1: Understand the error meaning

   The error means Python cannot find a module named 'app', which should be the filename without .py.

2. Step 2: Check the file existence

   If the file app.py is missing or you are in the wrong directory, this error occurs.

3. Final Answer:

   The Python file named app.py does not exist in the current directory -> Option C

4. Quick Check:

   ModuleNotFoundError means missing file/module [OK]

Hint: Check your file name and directory for the module [OK]

Common Mistakes:

• Assuming Uvicorn is not installed causes this error
• Thinking the FastAPI instance name causes ModuleNotFoundError
• Blaming --reload flag for import errors

5. You want to start a new FastAPI project. Which sequence correctly sets up and runs your app locally?

hard

A. pip install fastapi[all] -> create app.py -> uvicorn run app.py

B. pip install uvicorn -> create app.py -> python app.py

C. pip install fastapi -> create app.py -> fastapi run app.py

D. pip install fastapi[all] -> create app.py with FastAPI instance -> uvicorn app:app --reload

Solution

1. Step 1: Install FastAPI with all dependencies

   Use pip install fastapi[all] to get FastAPI and recommended tools like Uvicorn.

2. Step 2: Create your app.py file with a FastAPI instance named 'app'

   This file contains your API code and the FastAPI() instance.

3. Step 3: Run the app locally with Uvicorn and reload

   Use uvicorn app:app --reload to start the server with auto-reload for development.

4. Final Answer:

   pip install fastapi[all] -> create app.py with FastAPI instance -> uvicorn app:app --reload -> Option D

5. Quick Check:

   Install, create app, run with uvicorn --reload [OK]

Hint: Install FastAPI[all], create app.py, run uvicorn app:app --reload [OK]

Common Mistakes:

• Installing only uvicorn without FastAPI
• Trying to run app.py directly with python
• Using wrong uvicorn command syntax