例如，声明 `X-Token` 多次出现的请求头，可以写成这样：

{* ../../docs_src/header_params/tutorial003_an_py310.py hl[9] *}

与*路径操作*通信时，以下面的方式发送两个 HTTP 请求头：

```
X-Token: foo
X-Token: bar
```

响应结果是：

```JSON
{
    "X-Token values": [
        "bar",
        "foo"
    ]
}
```

## 小结 { #recap }

使用 `Header` 声明请求头的方式与 `Query`、`Path` 、`Cookie` 相同。

from typing import Annotated

from fastapi import FastAPI, Query

app = FastAPI()


@app.get("/items/")
async def read_items(q: Annotated[str | None, Query(min_length=3)]):
    results = {"items": [{"item_id": "Foo"}, {"item_id": "Bar"}]}
    if q:
        results.update({"q": q})

}

func ExampleEqualFold() {
	fmt.Println(bytes.EqualFold([]byte("Go"), []byte("go")))
	// Output: true
}

func ExampleFields() {
	fmt.Printf("Fields are: %q", bytes.Fields([]byte("  foo bar  baz   ")))
	// Output: Fields are: ["foo" "bar" "baz"]
}

func ExampleFieldsFunc() {
	f := func(c rune) bool {
		return !unicode.IsLetter(c) && !unicode.IsNumber(c)
	}

from typing import Annotated

from fastapi import FastAPI, Query

app = FastAPI()


@app.get("/items/")
async def read_items(q: Annotated[str | None, Query(alias="item-query")] = None):
    results = {"items": [{"item_id": "Foo"}, {"item_id": "Bar"}]}
    if q:
        results.update({"q": q})

from fastapi import FastAPI, Query

app = FastAPI()


@app.get("/items/")
async def read_items(
    q: Annotated[str | None, Query(min_length=3, max_length=50)] = None,
):
    results = {"items": [{"item_id": "Foo"}, {"item_id": "Bar"}]}
    if q:
        results.update({"q": q})

    ClassLoader classLoader = getClass().getClassLoader();
    assertThat(new ClassInfo(FILE, "Foo.class", classLoader).getSimpleName()).isEqualTo("Foo");
    assertThat(new ClassInfo(FILE, "a/b/Foo.class", classLoader).getSimpleName()).isEqualTo("Foo");
    assertThat(new ClassInfo(FILE, "a/b/Bar$Foo.class", classLoader).getSimpleName())
        .isEqualTo("Foo");
    assertThat(new ClassInfo(FILE, "a/b/Bar$1.class", classLoader).getSimpleName()).isEqualTo("");

            return true; // BAD!!
          }

          @Override
          public String get() {
            return "foo"; // BAD!!
          }

          @Override
          public String get(long time, TimeUnit unit) {
            return "foo"; // BAD!!
          }

          @Override
          public void addListener(Runnable runnable, Executor executor) {

            return ("{" + (char) c + "}").toCharArray();
          }
        };
    EscaperAsserts.assertBasic(wrappingEscaper);
    // '[' and '@' lie either side of [A-Z].
    assertThat(wrappingEscaper.escape("[FOO@BAR]")).isEqualTo("{[}FOO{@}BAR{]}");
  }

  public void testDeleteUnsafeChars() throws IOException {
    UnicodeEscaper deletingEscaper =
        new ArrayBasedUnicodeEscaper(NO_REPLACEMENTS, ' ', '~', null) {
          @Override

            return true; // BAD!!
          }

          @Override
          public String get() {
            return "foo"; // BAD!!
          }

          @Override
          public String get(long time, TimeUnit unit) {
            return "foo"; // BAD!!
          }

          @Override
          public void addListener(Runnable runnable, Executor executor) {

app = FastAPI()


@app.get("/items/")
async def read_items(
    q: Annotated[
        str | None, Query(min_length=3, max_length=50, pattern="^fixedquery$")
    ] = None,
):
    results = {"items": [{"item_id": "Foo"}, {"item_id": "Bar"}]}
    if q:
        results.update({"q": q})