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In this lesson, we will adjust the project structure to improve code organization by moving the main file into a dedicated folder named “app”. This change groups all application-specific code in one place and simplifies package management.

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FastAPI Endpoint for Updating a Post

Below is an example of a FastAPI endpoint for updating a post. Notice that this code sample is presented only once for clarity: 
@app.put("/posts/{id}")
def update_post(id: int, post: Post):
    index = find_index_post(id)

    if index is None:
        raise HTTPException(
            status_code=status.HTTP_404_NOT_FOUND,
            detail=f"Post with id: {id} does not exist"
        )

    post_dict = post.dict()
    post_dict['id'] = id
    my_posts[index] = post_dict
    return {"data": post_dict}

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Sample Console Output

The following snippet shows a sample of the console output you may see when making requests to the API: 
INFO:     127.0.0.1:63024 - "GET /posts HTTP/1.1" 200 OK
INFO:     127.0.0.1:60784 - "PUT /posts HTTP/1.1" 200 OK
INFO:     127.0.0.1:60785 - "GET /posts HTTP/1.1" 200 OK

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Restructuring the Project

We are now creating a new folder named app to store our main application file. In Python, a folder can be used as a package if it contains an __init__.py file.
Even though the __init__.py file can be empty, its presence is essential as it signals to Python that the folder should be treated as a package.
After creating the app folder and adding an __init__.py file inside it, move the main file into the app directory. At this point, you’ll encounter an error because the startup command is still referencing the main file from the base directory.

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Updating the Startup Command

Previously, the application was launched using a command similar to: 
(venv) C:\Users\sanje\Documents\Courses\fastapi>uvicorn main:app --reload
In this command, main referred to the file in the project’s base directory. Now that the main file has been moved into the app package, the startup command must be updated to indicate the new package location: 
(venv) C:\Users\sanje\Documents\Courses\fastapi>uvicorn app.main:app --reload
This updated command directs Uvicorn to search for the file named main within the app folder and then use the FastAPI instance (named app) defined therein.

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Main File Code Snippet

Below is a snippet from the main file for clarity: 
from typing import Optional
from fastapi import FastAPI, Response, status, HTTPException
from fastapi.params import Body
from pydantic import BaseModel
from random import randrange

app = FastAPI()

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Running the Application

After starting the application with the updated command, you might see output similar to the following: 
(venv) C:\Users\sanje\Documents\Courses\fastapi>uvicorn app.main:app --reload
INFO: Uvicorn running on http://127.0.0.1:8000 (Press CTRL+C to quit)
INFO: Started reloader process [21236] using watchgod
INFO: Started server process [4760]
INFO: Waiting for application startup.
INFO: Application startup complete.
127.0.0.1:50834 - "GET /posts/1 HTTP/1.1" 200 OK

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Verifying the Endpoint

Finally, test the endpoint for retrieving an individual post. For example, a GET request to the endpoint might return a JSON response similar to this: 
{
    "post_detail": {
        "title": "title of post 1",
        "content": "content of post 1",
        "id": 1
    }
}
Everything should now function as expected. This new structure will help keep your application code well-organized as you continue development.

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