from typing import Annotated, Union

from fastapi import Body, FastAPI
from pydantic import BaseModel

app = FastAPI()


class Item(BaseModel):
    name: str
    description: Union[str, None] = None
    price: float
    tax: Union[float, None] = None


@app.put("/items/{item_id}")
async def update_item(
    item_id: int,
    item: Annotated[
        Item,
        Body(
            examples=[
                {

from typing import Optional, Union

from dirty_equals import IsDict
from fastapi import FastAPI
from fastapi.testclient import TestClient
from pydantic import BaseModel

app = FastAPI()


class Item(BaseModel):
    name: Optional[str] = None


class ExtendedItem(Item):
    age: int


@app.post("/items/")
def save_union_different_body(item: Union[ExtendedItem, Item]):
    return {"item": item}

from typing import Annotated, Union

from fastapi import FastAPI, Query

app = FastAPI()


@app.get("/items/")
async def read_items(
    hidden_query: Annotated[Union[str, None], Query(include_in_schema=False)] = None,
):
    if hidden_query:
        return {"hidden_query": hidden_query}
    else:

from typing import Any, Union

from fastapi import FastAPI
from pydantic import BaseModel

app = FastAPI()


class Item(BaseModel):
    name: str
    description: Union[str, None] = None
    price: float
    tax: Union[float, None] = None
    tags: list[str] = []


@app.post("/items/", response_model=Item)
async def create_item(item: Item) -> Any:
    return item


@app.get("/items/", response_model=list[Item])

from typing import Union

from fastapi import Body, FastAPI
from pydantic import BaseModel
from typing_extensions import Annotated

app = FastAPI()


class Item(BaseModel):
    name: str
    description: Union[str, None] = None
    price: float
    tax: Union[float, None] = None


@app.put("/items/{item_id}")
async def update_item(
    item_id: int,
    item: Annotated[
        Item,
        Body(

from typing import Union

from fastapi import FastAPI, Query
from typing_extensions import Annotated

app = FastAPI()


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

from typing import Union

from fastapi import FastAPI, Response
from fastapi.responses import RedirectResponse

app = FastAPI()


@app.get("/portal")
async def get_portal(teleport: bool = False) -> Union[Response, dict]:
    if teleport:
        return RedirectResponse(url="https://www.youtube.com/watch?v=dQw4w9WgXcQ")

```

////

#### ⚙️ `Union` ⚖️ `Optional`

🚥 👆 ⚙️ 🐍 ⏬ 🔛 3️⃣.1️⃣0️⃣, 📥 💁‍♂ ⚪️➡️ 👇 📶 **🤔** ☝ 🎑:

* 👶 ❎ ⚙️ `Optional[SomeType]`
* ↩️ 👶 **⚙️ `Union[SomeType, None]`** 👶.

👯‍♂️ 🌓 & 🔘 👫 🎏, ✋️ 👤 🔜 👍 `Union` ↩️ `Optional` ↩️ 🔤 "**📦**" 🔜 😑 🔑 👈 💲 📦, & ⚫️ 🤙 ⛓ "⚫️ 💪 `None`", 🚥 ⚫️ 🚫 📦 & ✔.

👤 💭 `Union[SomeType, None]` 🌖 🔑 🔃 ⚫️❔ ⚫️ ⛓.

```Python hl_lines="7"
{!> ../../docs_src/query_params_str_validations/tutorial001_py310.py!}
```

////

🔢 🔢 `q` 🆎 `Union[str, None]` (⚖️ `str | None` 🐍 3️⃣.1️⃣0️⃣), 👈 ⛓ 👈 ⚫️ 🆎 `str` ✋️ 💪 `None`, & 👐, 🔢 💲 `None`, FastAPI 🔜 💭 ⚫️ 🚫 ✔.

/// note

FastAPI 🔜 💭 👈 💲 `q` 🚫 ✔ ↩️ 🔢 💲 `= None`.

 `Union` `Union[str, None]` 🔜 ✔ 👆 👨‍🎨 🤝 👆 👍 🐕‍🦺 & 🔍 ❌.

///

## 🌖 🔬

from typing import Union

from fastapi import Body, FastAPI
from pydantic import BaseModel, Field

app = FastAPI()


class Item(BaseModel):
    name: str
    description: Union[str, None] = Field(
        default=None, title="The description of the item", max_length=300
    )
    price: float = Field(gt=0, description="The price must be greater than zero")
    tax: Union[float, None] = None


@app.put("/items/{item_id}")