FastAPI installation and setup - Step-by-Step Execution

Concept Flow - FastAPI installation and setup

Start

↓

Check Python installed

↓

Install FastAPI via pip

↓

Install ASGI server (uvicorn)

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Create main.py with FastAPI app

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Run uvicorn server

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Access API in browser or client

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End

This flow shows the steps to install FastAPI, set up a basic app, run the server, and access the API.

Execution Sample

FastAPI

pip install fastapi
pip install "uvicorn[standard]"

# main.py
from fastapi import FastAPI
app = FastAPI()

@app.get("/")
def read_root():
    return {"Hello": "World"}

This code installs FastAPI and uvicorn, then creates a simple FastAPI app that returns a JSON greeting.

Execution Table

Step	Action	Command/Code	Result/Output
1	Check Python installed	python --version	Python 3.x.x (must be 3.7+)
2	Install FastAPI	pip install fastapi	FastAPI installed successfully
3	Install uvicorn server	pip install "uvicorn[standard]"	uvicorn installed successfully
4	Create main.py file	Write FastAPI app code	File main.py created with FastAPI app
5	Run uvicorn server	uvicorn main:app --reload	Server starts, listens on http://127.0.0.1:8000
6	Access API root	Open browser at http://127.0.0.1:8000/	Displays JSON: {"Hello": "World"}
7	Access docs	Open browser at http://127.0.0.1:8000/docs	Interactive API docs shown
8	Exit	Ctrl+C in terminal	Server stops

💡 User stops server manually with Ctrl+C

Variable Tracker

Variable	Start	After Step 4	After Step 5	Final
app	undefined	FastAPI instance created	Running FastAPI app instance	Running FastAPI app instance
server	not running	not running	uvicorn server running	server stopped

Key Moments - 3 Insights

Why do we need to install uvicorn separately after installing FastAPI?

FastAPI is the framework, but it needs an ASGI server like uvicorn to run the app and handle requests. See execution_table steps 2 and 3.

What does the --reload option do when running uvicorn?

It makes the server restart automatically when you change your code, so you don't have to stop and start manually. See execution_table step 5.

How do we know the server is running and ready to accept requests?

The terminal shows the server address (http://127.0.0.1:8000) after running uvicorn. You can open this in a browser to see the response. See execution_table step 6.

Visual Quiz - 3 Questions

Look at the execution_table, what command installs the FastAPI framework?

A pip install uvicorn

B pip install fastapi

C uvicorn main:app --reload

D python main.py

💡 Hint

Check Step 2 in the execution_table for the FastAPI installation command.

At which step does the server start listening for requests?

A Step 5

B Step 6

C Step 4

D Step 7

💡 Hint

Look for the step where uvicorn is run and the server address appears.

If you forget to install uvicorn, what will happen when you try to run the server?

A The server will run normally

B FastAPI will install uvicorn automatically

C You will get an error saying uvicorn command not found

D The app will run but no requests will be handled

💡 Hint

Refer to the need for uvicorn in steps 3 and 5 of the execution_table.

Concept Snapshot

FastAPI installation and setup:
1. Ensure Python 3.7+ is installed.
2. Install FastAPI with 'pip install fastapi'.
3. Install uvicorn server with 'pip install "uvicorn[standard]"'.
4. Create a Python file with FastAPI app code.
5. Run server using 'uvicorn main:app --reload'.
6. Access API at http://127.0.0.1:8000/ in browser.

Full Transcript

To set up FastAPI, first check that Python 3.7 or newer is installed. Then, install FastAPI using pip. Next, install uvicorn, which is the server that runs the FastAPI app. Create a Python file named main.py with a FastAPI app instance and a simple route. Run the server with uvicorn using the command 'uvicorn main:app --reload'. The server will start and listen on http://127.0.0.1:8000/. You can open this URL in a browser to see the JSON response. The /docs path shows interactive API documentation. Stop the server anytime with Ctrl+C.