{!../../../docs_src/bigger_applications/app/main.py!}
```

and it will work correctly, together with all the other *path operations* added with `app.include_router()`.

!!! info "Very Technical Details"
    **Note**: this is a very technical detail that you probably can **just skip**.

    ---

    The `APIRouter`s are not "mounted", they are not isolated from the rest of the application.

# Dependencies

**FastAPI** has a very powerful but intuitive **<abbr title="also known as components, resources, providers, services, injectables">Dependency Injection</abbr>** system.

It is designed to be very simple to use, and to make it very easy for any developer to integrate other components with **FastAPI**.

## What is "Dependency Injection"

    return {"item_id": item_id, "q": q}


@app.put("/items/{item_id}")
def update_item(item_id: int, item: Item):
    return {"item_name": item.name, "item_id": item_id}
```

O servidor deverá recarregar automaticamente (porquê você adicionou `--reload` ao comando `uvicorn` acima).

### Evoluindo a Documentação Interativa da API

# Help FastAPI - Get Help

Do you like **FastAPI**?

Would you like to help FastAPI, other users, and the author?

Or would you like to get help with **FastAPI**?

There are very simple ways to help (several involve just one or two clicks).

And there are several ways to get help too.

## Subscribe to the newsletter

<div class="termy">

```console
// Verwenden Sie das Kommando „serve“ nachdem Sie „build-all“ ausgeführt haben.
$ python ./scripts/docs.py serve

Warning: this is a very simple server. For development, use mkdocs serve instead.
This is here only to preview a site with translations already built.
Make sure you run the build-all command first.
Serving at: http://127.0.0.1:8008
```

To see how to achieve this parallelism in production see the section about [Deployment](deployment/index.md){.internal-link target=_blank}.

## `async` and `await`

* Базовая модель пользователя (измените или удалите её по необходимости).
* **Alembic** для организации миграций.
* **CORS** (Совместное использование ресурсов из разных источников).
* **Celery**, процессы которого могут выборочно импортировать и использовать модели и код из остальной части бэкенда.

For large responses, returning a `Response` directly is much faster than returning a dictionary.

## CRUD utils

Now let's see the file `sql_app/crud.py`.

### Create all the CRUD utils

Create all the same CRUD utils as in the SQLAlchemy tutorial, all the code is very similar:

```Python hl_lines="1  4-5  8-9  12-13  16-20  23-24  27-30"
{!../../../docs_src/sql_databases_peewee/sql_app/crud.py!}
```

There are some differences with the code for the SQLAlchemy tutorial.

    ```

### Check the password

At this point we have the user data from our database, but we haven't checked the password.

Let's put that data in the Pydantic `UserInDB` model first.

You should never save plaintext passwords, so, we'll use the (fake) password hashing system.

If the passwords don't match, we return the same error.

#### Password hashing