description: Union[str, None] = None
    price: float
    tax: Union[float, None] = None
    tags: Set[str] = set()


@app.post("/items/", response_model=Item, summary="Create an item")
async def create_item(item: Item):
    """
    Create an item with all the information:

    - **name**: each item must have a name
    - **description**: a long description
    - **price**: required

from typing import 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: set[str] = set()


@app.post(
    "/items/",
    response_model=Item,
    summary="Create an item",
    response_description="The created item",
)

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}")
async def update_item(item_id: int, item: Annotated[Item, Body(embed=True)]):

{* ../../docs_src/python_types/tutorial004.py hl[2] *}

## Declaring types

You just saw the main place to declare type hints. As function parameters.

This is also the main place you would use them with **FastAPI**.

### Simple types

You can declare all the standard Python types, not only `str`.

You can use, for example:

* `int`

	a := arena.NewArena()
	defer a.Free()

	tt := arena.New[T1](a)
	tt.n = 1

	ts := arena.MakeSlice[T1](a, 99, 100)
	if len(ts) != 99 {
		t.Errorf("Slice() len = %d, want 99", len(ts))
	}
	if cap(ts) != 100 {
		t.Errorf("Slice() cap = %d, want 100", cap(ts))
	}
	ts[1].n = 42
}

func TestSmokeLarge(t *testing.T) {
	a := arena.NewArena()
	defer a.Free()
	for i := 0; i < 10*64; i++ {

		expect clause.Values
	}{
		{
			name: "Test convert slice of string value",
			input: []map[string]interface{}{
				{"name": "my name"},
			},
			expect: clause.Values{
				Columns: []clause.Column{{Name: "name"}},
				Values:  [][]interface{}{{"my name"}},
			},
		},
		{
			name: "Test convert slice of int value",
			input: []map[string]interface{}{
				{"age": 18},
			},

        "email": "******@****.***",
        "hashed_password": "$2b$12$EixZaYVK1fsbw1ZfbX3OXePaWxn96p36WQoeG6Lruj3vjPGga31lW",
        "disabled": False,
    },
    "alice": {
        "username": "alice",
        "full_name": "Alice Chains",
        "email": "******@****.***",
        "hashed_password": "$2b$12$gSvqqUPvlXP2tfVFaWK1Be7DlH.PKZbv5H8KnzzVgXXbVxpva.pFm",
        "disabled": True,
    },
}

        "email": "******@****.***",
        "hashed_password": "$2b$12$EixZaYVK1fsbw1ZfbX3OXePaWxn96p36WQoeG6Lruj3vjPGga31lW",
        "disabled": False,
    },
    "alice": {
        "username": "alice",
        "full_name": "Alice Chains",
        "email": "******@****.***",
        "hashed_password": "$2b$12$gSvqqUPvlXP2tfVFaWK1Be7DlH.PKZbv5H8KnzzVgXXbVxpva.pFm",
        "disabled": True,
    },
}

Esto también significa que en muchos casos puedes pasar el mismo objeto que obtuviste de un request **directamente a la base de datos**, dado que todo es validado automáticamente.

Lo mismo aplica para el sentido contrario. En muchos casos puedes pasar el objeto que obtienes de la base de datos **directamente al cliente**.

```JSON hl_lines="2"
{
    "item": {
        "name": "Foo",
        "description": "The pretender",
        "price": 42.0,
        "tax": 3.2
    }
}
```

instead of:

```JSON
{
    "name": "Foo",
    "description": "The pretender",
    "price": 42.0,
    "tax": 3.2
}
```

## Recap