### `StreamingResponse` { #streamingresponse }

接收一個 async 產生器或一般的產生器／疊代器（帶有 `yield` 的函式），並以串流方式傳送回應本文。

{* ../../docs_src/custom_response/tutorial007_py310.py hl[3,16] *}

/// note | 技術細節

一個 `async` 任務只能在抵達某個 `await` 時才能被取消。如果沒有 `await`，該產生器（帶有 `yield` 的函式）將無法被正確取消，甚至在請求取消後仍可能持續執行。

因為這個小範例不需要任何 `await` 陳述式，我們加入 `await anyio.sleep(0)`，讓事件迴圈有機會處理取消。

對於大型或無限的串流來說，這點更為重要。

    static final GetCheckedTypeValidator BEST_VALIDATOR = getBestValidator();

    enum WeakSetValidator implements GetCheckedTypeValidator {
      INSTANCE;

      /*
       * Static final fields are presumed to be fastest, based on our experience with
       * UnsignedBytesBenchmark. TODO(cpovirk): benchmark this
       */
      /*

        // Verify the interface extends Serializable
        assertTrue(user instanceof java.io.Serializable);
    }

    @Test
    public void test_allFieldsCombination() {
        // Test with all fields populated
        String name = "complexUser";
        String[] roles = { "admin", "user", "viewer" };
        String[] groups = { "developers", "managers", "qa" };

We have 3 different things that we synchronize on.

#### Http2Connection

This lock guards internal state of each connection. This lock is never held for blocking operations. That means that we acquire the lock, read or write a few fields and release the lock. No I/O and no application-layer callbacks.

#### Http2Stream

  }

  private static final int ENDPOINT = -2;

  // TODO(user): predecessors and successors should be collocated (reducing cache misses).
  // Might also explore collocating all of [hash, next, predecessor, successor] fields of an
  // entry in a *single* long[], though that reduces the maximum size of the set by a factor of 2

  /**
   * Pointer to the predecessor of an entry in insertion order. ENDPOINT indicates a node is the

  }

  private static final int ENDPOINT = -2;

  // TODO(user): predecessors and successors should be collocated (reducing cache misses).
  // Might also explore collocating all of [hash, next, predecessor, successor] fields of an
  // entry in a *single* long[], though that reduces the maximum size of the set by a factor of 2

  /**
   * Pointer to the predecessor of an entry in insertion order. ENDPOINT indicates a node is the

			return err
		}
	case !f.Tag.IsEmpty():
		if err := e.EncodeElement(f.Tag, xml.StartElement{Name: xml.Name{Local: "Tag"}}); err != nil {
			return err
		}
	default:
		// Always print Prefix field when both And & Tag are empty
		if err := e.EncodeElement(f.Prefix, xml.StartElement{Name: xml.Name{Local: "Prefix"}}); err != nil {
			return err
		}

		if f.ObjectSizeLessThan > 0 {

* 그런 다음 **요청**을 나머지 애플리케이션(어떤 *경로 처리*가)을 통해 처리되도록 전달합니다.
* 그런 다음 애플리케이션(어떤 *경로 처리*가)이 생성한 **응답**을 가져옵니다.
* 그런 다음 해당 **응답**에 대해 무언가를 하거나 필요한 코드를 실행할 수 있습니다.
* 그런 다음 **응답**을 반환합니다.

/// note | 기술 세부사항

`yield`를 사용하는 의존성이 있다면, exit 코드는 미들웨어 *후에* 실행됩니다.

백그라운드 작업(뒤에서 보게 될 [백그라운드 작업](background-tasks.md) 섹션에서 다룹니다)이 있다면, 모든 미들웨어 *후에* 실행됩니다.

///

## 미들웨어 만들기 { #create-a-middleware }

from enum import Enum
from typing import Annotated, Any, Literal

from fastapi.exceptions import FastAPIDeprecationWarning
from fastapi.openapi.models import Example
from pydantic import AliasChoices, AliasPath
from pydantic.fields import FieldInfo
from typing_extensions import deprecated

from ._compat import (
    Undefined,
)
from .datastructures import _Unset


class ParamTypes(Enum):
    query = "query"
    header = "header"

	if db5.Error != nil {
		t.Errorf("Should not raise error for join where identical fields in different tables. Error: %s", db5.Error.Error())
	}

	var users6 []User
	DB.Joins("inner join pets on pets.user_id = users.id AND pets.name = @Name", user.Pets[0]).Where("users.name = ?", user.Name).First(&users6)