```

////

## Declare `Header` parameters

Then declare the header parameters using the same structure as with `Path`, `Query` and `Cookie`.

You can define the default value as well as all the extra validation or annotation parameters:

//// tab | Python 3.10+

```Python hl_lines="9"
{!> ../../docs_src/header_params/tutorial001_an_py310.py!}
```

////

//// tab | Python 3.9+

from typing import List

from fastapi import FastAPI, Query
from pydantic import BaseModel, Field
from typing_extensions import Literal

app = FastAPI()


class FilterParams(BaseModel):
    model_config = {"extra": "forbid"}

    limit: int = Field(100, gt=0, le=100)
    offset: int = Field(0, ge=0)
    order_by: Literal["created_at", "updated_at"] = "created_at"
    tags: List[str] = []


@app.get("/items/")

 * the License.
 */

package com.google.common.base;

import org.checkerframework.checker.nullness.qual.Nullable;

/** Holder for extra methods of {@code Objects} only in web. */
public abstract class ExtraObjectsMethodsForWeb {
  public static boolean equal(@Nullable String a, @Nullable String b) {
    return a == b;
  }

              {{- if and .Values.persistence.enabled .Values.persistence.subPath }}
              subPath: "{{ .Values.persistence.subPath }}"
              {{- end }}
            {{- if .Values.extraSecret }}
            - name: extra-secret
              mountPath: "/tmp/minio-config-env"
            {{- end }}
            {{- include "minio.tlsKeysVolumeMount" . | indent 12 }}
            {{- if .Values.extraVolumeMounts }}

        }
        if (elements.length > 1) {
          /*
           * When a test requests a multiset with duplicates, our plan of
           * "add an extra item 0 to A and an extra item 1 to B" really means
           * "add an extra item 0 to A and B," which isn't what we want.
           */
          if (!Objects.equal(elements[0], elements[1])) {
            multiset2.add(elements[1], 2);
          }

Sie werden später mehr darüber lernen, wie man zusätzliche Information unterbringt, wenn Sie lernen, Beispiele zu deklarieren.

/// warning | "Achtung"

 * limitations under the License.
 */
package okhttp3.testing

@Target(AnnotationTarget.CLASS, AnnotationTarget.FUNCTION)
@Retention(AnnotationRetention.RUNTIME)
/**
 * Annotation marking a test as flaky, and requires extra logging and linking against
 * a known github issue.  This does not ignore the failure.
 */

        ) -> CoreSchema:
            return with_info_plain_validator_function(cls._validate)


class BaseModelWithConfig(BaseModel):
    if PYDANTIC_V2:
        model_config = {"extra": "allow"}

    else:

        class Config:
            extra = "allow"


class Contact(BaseModelWithConfig):
    name: Optional[str] = None
    url: Optional[AnyUrl] = None
    email: Optional[EmailStr] = None

) string {
	extra := make([]string, 0)
	if lb != nil {
		extra = append(extra, "load balancer")
	}
	if connectionPool != nil {
		extra = append(extra, "connection pool")
	}
	if outlierDetection != nil {
		extra = append(extra, "outlier detection")
	}
	if len(extra) > 0 {
		return fmt.Sprintf("Policies: %s\n", strings.Join(extra, "/"))
	}
	return ""
}

from typing import Annotated

from fastapi import Cookie, FastAPI
from pydantic import BaseModel

app = FastAPI()


class Cookies(BaseModel):
    model_config = {"extra": "forbid"}

    session_id: str
    fatebook_tracker: str | None = None
    googall_tracker: str | None = None


@app.get("/items/")
async def read_items(cookies: Annotated[Cookies, Cookie()]):