```

Read the new docs: [Query Parameter Models](https://fastapi.tiangolo.com/tutorial/query-param-models/).

#### `Header` Parameter Models

Use Pydantic models for `Header` parameters:

```python
from typing import Annotated

from fastapi import FastAPI, Header
from pydantic import BaseModel

app = FastAPI()


class CommonHeaders(BaseModel):
    host: str
    save_data: bool

	if err != nil {
		return err
	}

	if len(data) == 0 {
		return nil
	}
	if len(data) <= 4 {
		return fmt.Errorf("rebalanceMeta: no data")
	}

	// Read header
	switch binary.LittleEndian.Uint16(data[0:2]) {
	case rebalMetaFmt:
	default:
		return fmt.Errorf("rebalanceMeta: unknown format: %d", binary.LittleEndian.Uint16(data[0:2]))
	}

     * key and value, which we pass to the superconstructor, even though the key and value type for
     * a given entry might not include null. The right fix for the header problems is probably to
     * define a separate MultimapLink interface with a separate "header" implementation, which
     * hopefully could avoid implementing Entry or ValueSetLink at all. (But note that that approach

    * JSON.
    * Pfad-Parametern.
    * Abfrage-Parametern.
    * Cookies.
    * Header-Feldern.
    * Formularen.
    * Dateien.
* <abbr title="auch bekannt als: Serialisierung, Parsen, Marshalling">Konvertierung</abbr> von Ausgabedaten: Konvertierung von Python-Daten und -Typen zu Netzwerkdaten (als JSON):

Also fügen wir sie in ihr eigenes `dependencies`-Modul (`app/dependencies.py`) ein.

Wir werden nun eine einfache Abhängigkeit verwenden, um einen benutzerdefinierten `X-Token`-Header zu lesen:

//// tab | Python 3.9+

```Python hl_lines="3  6-8" title="app/dependencies.py"
{!> ../../docs_src/bigger_applications/app_an_py39/dependencies.py!}
```

////

//// tab | Python 3.8+

  /**
   * Returns true if this cookie's domain should be interpreted as a single host name, or false if
   * it should be interpreted as a pattern. This flag will be false if its `Set-Cookie` header
   * included a `domain` attribute.
   *
   * For example, suppose the cookie's domain is `example.com`. If this flag is true it matches

    * JSON.
    * <abbr title="Yol: Path">Yol</abbr> parametrləri.
    * <abbr title="Sorğu: Query">Sorğu</abbr> parametrləri.
    * <abbr title="Çərəz: Cookie">Çərəzlər</abbr>.
    * <abbr title="Başlıq: Header">Başlıqlaq</abbr>.
    * <abbr title="Forma: Form">Formalar</abbr>.
    * Fayllar.

   *     CLEAN 1ab96a171faeeee38496d8b330771a7a 1600 234
   *     READ 335c4c6028171cfddfbaae1a9c313c52
   *     READ 3400330d1dfc7f3f7f4b8d4d803dfcf6
   *
   * The first five lines of the journal form its header. They are the constant string
   * "libcore.io.DiskLruCache", the disk cache's version, the application's version, the value
   * count, and a blank line.
   *

It has a `GET` operation that could return an error.

It has a `POST` operation that could return several errors.

Both *path operations* require an `X-Token` header.

//// tab | Python 3.10+

```Python
{!> ../../docs_src/app_testing/app_b_an_py310/main.py!}
```

////

//// tab | Python 3.9+

```Python

		header, zerr := zip.FileInfoHeader(dummyFileInfo{
			name:    filename,
			size:    int64(sz),
			mode:    0o600,
			modTime: time.Now(),
			isDir:   false,
			sys:     nil,
		})
		if zerr != nil {
			adminLogIf(ctx, zerr)
			return nil
		}
		header.Method = zip.Deflate
		zwriter, zerr := zipWriter.CreateHeader(header)
		if zerr != nil {