* one or more methods to modify the behavior of the backing multiset as desired per the <a
 * href="http://en.wikipedia.org/wiki/Decorator_pattern">decorator pattern</a>.
 *
 * <p><b>Warning:</b> The methods of {@code ForwardingMultiset} forward <b>indiscriminately</b> to
 * the methods of the delegate. For example, overriding {@link #add(Object, int)} alone <b>will

 * override one or more methods to modify the behavior of the backing map as desired per the <a
 * href="http://en.wikipedia.org/wiki/Decorator_pattern">decorator pattern</a>.
 *
 * <p><b>Warning:</b> The methods of {@code ForwardingNavigableMap} forward <i>indiscriminately</i>
 * to the methods of the delegate. For example, overriding {@link #put} alone <i>will not</i> change

```Python
def get_settings():
    return Settings()
```

we would create that object for each request, and we would be reading the `.env` file for each request. ⚠️

But as we are using the `@lru_cache` decorator on top, the `Settings` object will be created only once, the first time it's called. ✔️

{* ../../docs_src/settings/app03_an_py310/main.py hl[1,11] *}

 * override one or more methods to modify the behavior of the backing map as desired per the <a
 * href="http://en.wikipedia.org/wiki/Decorator_pattern">decorator pattern</a>.
 *
 * <p><b>Warning:</b> The methods of {@code ForwardingNavigableMap} forward <i>indiscriminately</i>
 * to the methods of the delegate. For example, overriding {@link #put} alone <i>will not</i> change

### When to use `response_model` instead

If the return type is not the same as the type that you want to use to validate, filter, or serialize, use the `response_model` parameter on the decorator instead.

```python
from typing import Any

from fastapi import FastAPI
from pydantic import BaseModel

app = FastAPI()


class Item(BaseModel):
    name: str

* to serve the application
* to serve the page

* the app
* the application

* the request
* the response
* the error response

* the path operation
* the path operation decorator
* the path operation function

* the body
* the request body
* the response body
* the JSON body
* the form body
* the file body
* the function body

* the parameter

///

FastAPI 在 `fastapi.security.oauth2` 中提供了所有這些 OAuth2 驗證流程的工具。

## 在裝飾器 `dependencies` 中使用 `Security` { #security-in-decorator-dependencies }

## *Path Operation Decorator*'üne `dependencies` Ekleyin { #add-dependencies-to-the-path-operation-decorator }

*Path operation decorator*, opsiyonel bir `dependencies` argümanı alır.

Bu, `Depends()` öğelerinden oluşan bir `list` olmalıdır:

{* ../../docs_src/dependencies/tutorial006_an_py310.py hl[19] *}

///

**FastAPI** 在 `fastapi.security.oauth2` 中为所有这些 OAuth2 身份验证流提供了工具。

## 装饰器 `dependencies` 中的 `Security` { #security-in-decorator-dependencies }

    * If you also declare dependencies in a specific *path operation*, **they will be executed too**.
    * The router dependencies are executed first, then the [`dependencies` in the decorator](dependencies/dependencies-in-path-operation-decorators.md), and then the normal parameter dependencies.
    * You can also add [`Security` dependencies with `scopes`](../advanced/security/oauth2-scopes.md).

/// tip