Bill Zhong <******@****.***> 1713829269 -0230

## 0.31.0

* Upgrade Pydantic supported version to `0.29.0`.
    * New supported version range is `"pydantic >=0.28,<=0.29.0"`.
    * This adds support for Pydantic [Generic Models](https://docs.pydantic.dev/latest/#generic-models), kudos to [@dmontagu](https://github.com/dmontagu).
    * PR [#344](https://github.com/tiangolo/fastapi/pull/344).

## 0.30.1

* **`400`** and above are for "Client error" responses. These are the second type you would probably use the most.
    * An example is `404`, for a "Not Found" response.
    * For generic errors from the client, you can just use `400`.

```Python hl_lines="31-33"
{!../../../docs_src/nosql_databases/tutorial001.py!}
```

!!! note
    Notice that we have a `hashed_password` and a `type` field that will be stored in the database.

    But it is not part of the general `User` model (the one we will return in the *path operation*).

## Get the user

Now create a function that will:

* Take a username.
* Generate a document ID from it.
* Get the document with that ID.

### Run Automatically on Startup

In general, you will probably want the server program (e.g. Uvicorn) to be started automatically on server startup, and without needing any **human intervention**, to have a process always running with your API (e.g. Uvicorn running your FastAPI app).

#### Generic tipler

Köşeli parantez içinde tip parametreleri alan bu türler, örneğin:

* `List`
* `Tuple`
* `Set`
* `Dict`
* `Optional`
* ...and others.

**Generic types** yada  **Generics** olarak adlandırılır.

### Tip olarak Sınıflar

Bir değişkenin tipini bir sınıf ile bildirebilirsiniz.

```

`Optional[str]`을 `str` 대신 쓰게 되면, 특정 값이 실제로는 `None`이 될 수도 있는데 항상 `str`이라고 가정하는 상황에서 에디터가 에러를 찾게 도와줄 수 있습니다.

#### Generic(제네릭) 타입

이 타입은 대괄호 안에 매개변수를 가지며, 종류는:

* `List`
* `Tuple`
* `Set`
* `Dict`
* `Optional`
* ...등등

위와 같은 타입은 **Generic(제네릭) 타입** 혹은 **Generics(제네릭스)**라고 불립니다.

### 타입으로서의 클래스

변수의 타입으로 클래스를 선언할 수도 있습니다.

이름(name)을 가진 `Person` 클래스가 있다고 해봅시다.

RequestErrorModel: Type[BaseModel] = create_model("Request")
WebSocketErrorModel: Type[BaseModel] = create_model("WebSocket")


class FastAPIError(RuntimeError):
    """
    A generic, FastAPI-specific error.
    """


class ValidationException(Exception):
    def __init__(self, errors: Sequence[Any]) -> None:
        self._errors = errors

    def errors(self) -> Sequence[Any]:

    ```Python hl_lines="10"
    {!> ../../../docs_src/query_params_str_validations/tutorial014.py!}
    ```

## Recap

You can declare additional validations and metadata for your parameters.

Generic validations and metadata:

* `alias`
* `title`
* `description`
* `deprecated`

Validations specific for strings:

* `min_length`
* `max_length`
* `pattern`

Nils Lindemann <******@****.***> 1711822722 +0100