Set Up Python fast API

To start a project with FastAPI in Python, follow these steps:

1. Install Python & Dependencies

Make sure you have Python 3.7 or later installed. You can check your Python version with:

python --version

2. Create a virtual environment:

3.  python -m venv .venv
   

4. Activate the virtual environment:

   • On Windows:

       .venv\Scripts\activate
     

   • On macOS/Linux:

       source .venv/bin/activate
     

install them using pip:

pip install fastapi uvicorn

2. Create main.py

from fastapi import FastAPI

app = FastAPI()

@app.get("/")
def read_root():
    return {"message": "Hello, FastAPI!"}

4. Run the FastAPI Application

Now, you can run the FastAPI app using uvicorn. From your project directory, run:

uvicorn main:app --reload

• main: This refers to the Python file main.py (without the .py extension).

• app: This is the FastAPI app instance.

• --reload: This flag enables auto-reloading during development, so the server restarts when you make changes to your code.

You should see output similar to this:

INFO:     Will watch for changes in these directories: ['<your_project_directory>']
INFO:     Uvicorn running on http://127.0.0.1:8000 (Press CTRL+C to quit)

5. Access the FastAPI App

Open a browser and go to:

http://127.0.0.1:8000

You should see a JSON response:

{
  "message": "Hello, FastAPI!"
}

6. Explore the Documentation

FastAPI automatically generates interactive documentation for your API. To view it:

• Swagger UI: Go to http://127.0.0.1:8000/docs

• ReDoc: Go to http://127.0.0.1:8000/redoc

  

7. Add More Routes

You can add more endpoints (routes) to your app by defining more functions with FastAPI decorators. For example:

from fastapi import FastAPI

app = FastAPI()

@app.get("/")
def read_root():
    return {"message": "Hello, FastAPI!"}

@app.get("/items/{item_id}")
def read_item(item_id: int, q: str = None):
    return {"item_id": item_id, "q": q}

In this case, the endpoint /items/{item_id} will accept an item_id as a URL parameter, and an optional query parameter q.

8. Test Your API

You can test the new /items/{item_id} endpoint by navigating to:

http://127.0.0.1:8000/items/42?q=test

This should return:

{
  "item_id": 42,
  "q": "test"
}

10. Optional: Create a requirements.txt

To share the project with others, you can generate a requirements.txt file that lists all your dependencies:

pip freeze > requirements.txt

Others can install the dependencies by running:

pip install -r requirements.txt