But **FastAPI** will know that it has to solve `query_extractor` first, to pass the results of that to `query_or_cookie_extractor` while calling it.

///

```mermaid
graph TB

query_extractor(["query_extractor"])
query_or_cookie_extractor(["query_or_cookie_extractor"])

read_query["/items/"]

query_extractor --> query_or_cookie_extractor --> read_query
```

* Sich das Ergebnis von dieser Funktion zu holen.
* Dieses Ergebnis dem Parameter Ihrer *Pfadoperation-Funktion* zuzuweisen.

```mermaid
graph TB

common_parameters(["common_parameters"])
read_items["/items/"]
read_users["/users/"]

common_parameters --> read_items
common_parameters --> read_users
```

    assertEquals(
        "a&quot;b&lt;c&gt;d&amp;e&quot;f&apos;", xmlAttributeEscaper.escape("a\"b<c>d&e\"f'"));
    // Test '\t', '\n' and '\r' are escaped.
    assertEquals("a&#x9;b&#xA;c&#xD;d", xmlAttributeEscaper.escape("a\tb\nc\rd"));
  }

  // Helper to assert common properties of xml escapers.
  static void assertBasicXmlEscaper(
      CharEscaper xmlEscaper, boolean shouldEscapeQuotes, boolean shouldEscapeWhitespaceChars) {

        } else if (size.divide(ONE_TB_BI).compareTo(BigInteger.ZERO) > 0) {
            displaySize = new BigDecimal(size.divide(ONE_GB_BI)).divide(BigDecimal.valueOf(1000)) + "TB";
        } else if (size.divide(ONE_GB_BI).compareTo(BigInteger.ZERO) > 0) {
            displaySize = new BigDecimal(size.divide(ONE_MB_BI)).divide(BigDecimal.valueOf(1000)) + "GB";

			}
		}
		if should < 10 {
			t.Errorf("host %q only connects to %d hosts", hosts[x], should)
		}
		t.Logf("host %q should connect to %d hosts", hosts[x], should)
	}
}

func startServer(t testing.TB, listener net.Listener, handler http.Handler) (server *httptest.Server) {
	t.Helper()
	server = httptest.NewUnstartedServer(handler)
	server.Config.Addr = listener.Addr().String()
	server.Listener = listener

次の章では、関数以外の「もの」が依存関係として使用できるものを見ていきます。

///

新しいリクエストが到着するたびに、**FastAPI** が以下のような処理を行います:

* 依存関係（"dependable"）関数を正しいパラメータで呼び出します。
* 関数の結果を取得します。
* *path operation関数*のパラメータにその結果を代入してください。

```mermaid
graph TB

common_parameters(["common_parameters"])
read_items["/items/"]
read_users["/users/"]

common_parameters --> read_items
common_parameters --> read_users
```

* Вызове вашей зависимости ("зависимого") функции с корректными параметрами.
* Получении результата из вашей функции.
* Назначении результата в параметр в вашей *функции обработки пути*.

```mermaid
graph TB

common_parameters(["common_parameters"])
read_items["/items/"]
read_users["/users/"]

common_parameters --> read_items
common_parameters --> read_users
```

pkg sync, method (*Map) LoadAndDelete(interface{}) (interface{}, bool)
pkg testing, method (*B) TempDir() string
pkg testing, method (*T) Deadline() (time.Time, bool)
pkg testing, method (*T) TempDir() string
pkg testing, type TB interface, TempDir() string

Aber **FastAPI** wird wissen, dass es zuerst `query_extractor` auflösen muss, um dessen Resultat `query_or_cookie_extractor` zu übergeben, wenn dieses aufgerufen wird.

///

```mermaid
graph TB

query_extractor(["query_extractor"])
query_or_cookie_extractor(["query_or_cookie_extractor"])

read_query["/items/"]

query_extractor --> query_or_cookie_extractor --> read_query
```

```

/// info | "信息"

注意，这里在*路径操作函数*中只声明了一个依赖项，即 `query_or_cookie_extractor` 。

但 **FastAPI** 必须先处理 `query_extractor`，以便在调用 `query_or_cookie_extractor` 时使用 `query_extractor` 返回的结果。

///

```mermaid
graph TB

query_extractor(["query_extractor"])
query_or_cookie_extractor(["query_or_cookie_extractor"])

read_query["/items/"]

query_extractor --> query_or_cookie_extractor --> read_query
```

## 多次使用同一个依赖项