{
                                                "name": "Baz",
                                                "price": "thirty five point four",
                                            },
                                        ],
                                    }
                                )
                                | IsDict(

                },
                {
                    "name": "Bar",
                    "price": "35.4",
                },
                {
                    "name": "Baz",
                    "price": "thirty five point four",
                },
            ],
        ),
    ],
):
    results = {"item_id": item_id, "item": item}

                },
                {
                    "name": "Bar",
                    "price": "35.4",
                },
                {
                    "name": "Baz",
                    "price": "thirty five point four",
                },
            ],
        ),
    ],
):
    results = {"item_id": item_id, "item": item}

                                        "value": {
                                            "name": "Baz",
                                            "price": "thirty five point four",
                                        },
                                    },
                                },
                            }
                        },

Now, let's see the module at `app/main.py`.

Here's where you import and use the class `FastAPI`.

This will be the main file in your application that ties everything together.

And as most of your logic will now live in its own specific module, the main file will be quite simple.

### Import `FastAPI`

You import and create a `FastAPI` class as normally.

    !!! tip
        Prefer to use the `Annotated` version if possible.

    ```Python hl_lines="10"
    {!> ../../../docs_src/security/tutorial001.py!}
    ```

But that is still not that useful.

Let's make it give us the current user.

## Create a user model

First, let's create a Pydantic user model.

The same way we use Pydantic to declare bodies, we can use it anywhere else:

=== "Python 3.10+"

```Python hl_lines="7"
{!../../../docs_src/path_params/tutorial002.py!}
```

In this case, `item_id` is declared to be an `int`.

!!! check
    This will give you editor support inside of your function, with error checks, completion, etc.

## Data <abbr title="also known as: serialization, parsing, marshalling">conversion</abbr>

!!! tip
    La langue principale ("officielle") est l'anglais, qui se trouve à l'adresse "docs/en/".

Maintenant, lancez le serveur en live pour les documents en espagnol :

<div class="termy">

```console
// Use the command "live" and pass the language code as a CLI argument
$ python ./scripts/docs.py live es

<span style="color: green;">[INFO]</span> Serving on http://127.0.0.1:8008

    "name": "Foo",
    "description": "The pretender",
    "price": 42.0,
    "tax": 3.2,
    "tags": ["rock", "metal", "bar"],
    "image": {
        "url": "http://example.com/baz.jpg",
        "name": "The Foo live"
    }
}
```

다시 한번, **FastAPI**를 사용하여 해당 선언을 함으로써 얻는 것은:

* 중첩 모델도 편집기 지원(자동완성 등)
* 데이터 변환
* 데이터 검증
* 자동 문서화

## 특별한 타입과 검증

    "name": "Foo",
    "description": "The pretender",
    "price": 42.0,
    "tax": 3.2,
    "tags": ["rock", "metal", "bar"],
    "image": {
        "url": "http://example.com/baz.jpg",
        "name": "The Foo live"
    }
}
```

Again, doing just that declaration, with **FastAPI** you get:

* Editor support (completion, etc.), even for nested models
* Data conversion
* Data validation