/// note | Hinweis

Wenn Sie eine <a href="https://docs.pydantic.dev/latest/concepts/types/#unions" class="external-link" target="_blank">`Union`</a> definieren, listen Sie den spezifischeren Typ zuerst auf, gefolgt vom weniger spezifischen Typ. Im Beispiel unten steht `PlaneItem` vor `CarItem` in `Union[PlaneItem, CarItem]`.

///

    Unicode U+201C (LEFT DOUBLE QUOTATION MARK) and Unicode U+201D (RIGHT DOUBLE QUOTATION MARK)

"English single typographic quotes"

    The characters «‘» and «’»
    Unicode U+2018 (LEFT SINGLE QUOTATION MARK) and Unicode U+2019 (RIGHT SINGLE QUOTATION MARK)

"code snippet"

### Target language

Translate to German (Deutsch).

Language code: de.


### Definitions

"hyphen"
    The character «-»
    Unicode U+002D (HYPHEN-MINUS)
    Alternative names: hyphen, dash, minus sign

"dash"
    The character «–»
    Unicode U+2013 (EN DASH)
    German name: Halbgeviertstrich


### Grammar to use when talking to the reader

Use the formal grammar (use «Sie» instead of «Du»).

    headers: Optional[dict[str, Union[Header, Reference]]] = None
    securitySchemes: Optional[dict[str, Union[SecurityScheme, Reference]]] = None
    links: Optional[dict[str, Union[Link, Reference]]] = None
    # Using Any for Specification Extensions
    callbacks: Optional[dict[str, Union[dict[str, PathItem], Reference, Any]]] = None
    pathItems: Optional[dict[str, Union[PathItem, Reference]]] = None

from dataclasses import dataclass, field
from typing import Union

from fastapi import FastAPI


@dataclass
class Item:
    name: str
    price: float
    tags: list[str] = field(default_factory=list)
    description: Union[str, None] = None
    tax: Union[float, None] = None


app = FastAPI()


@app.get("/items/next", response_model=Item)
async def read_next_item():
    return {
        "name": "Island In The Moon",

    name: str
    mode: Literal["validation", "serialization"] = "validation"
    config: Union[ConfigDict, None] = None

    @property
    def alias(self) -> str:
        a = self.field_info.alias
        return a if a is not None else self.name

    @property
    def validation_alias(self) -> Union[str, None]:
        va = self.field_info.validation_alias
        if isinstance(va, str) and va:

@app.get(
    "/response_model_union-no_annotation-return_model1",
    response_model=Union[User, Item],
)
def response_model_union_no_annotation_return_model1():
    return DBUser(name="John", surname="Doe", password_hash="secret")


@app.get(
    "/response_model_union-no_annotation-return_model2",
    response_model=Union[User, Item],
)
def response_model_union_no_annotation_return_model2():

from dataclasses import field  # (1)
from typing import Union

from fastapi import FastAPI
from pydantic.dataclasses import dataclass  # (2)


@dataclass
class Item:
    name: str
    description: Union[str, None] = None


@dataclass
class Author:
    name: str
    items: list[Item] = field(default_factory=list)  # (3)


app = FastAPI()


@app.post("/authors/{author_id}/items/", response_model=Author)  # (4)

from typing import Union

from fastapi import Body, Cookie, FastAPI, Header, Path, Query
from fastapi.testclient import TestClient
from pydantic import BaseModel

app = FastAPI()


class Item(BaseModel):
    data: str


@app.post("/examples/")
def examples(
    item: Item = Body(
        examples=[
            {"data": "Data in Body examples, example1"},
        ],
        openapi_examples={
            "Example One": {

from typing import Union

from fastapi import FastAPI
from fastapi.testclient import TestClient
from pydantic import BaseModel, ConfigDict


class FooBaseModel(BaseModel):
    model_config = ConfigDict(extra="forbid")


class Foo(FooBaseModel):
    pass


app = FastAPI()


@app.post("/")
async def post(
    foo: Union[Foo, None] = None,
):
    return foo


client = TestClient(app)