```JSON
{
    "name": "Foo",
    "description": "An optional description",
    "price": 45.2,
    "tax": 3.5
}
```

...as `description` and `tax` are optional (with a default value of `None`), this JSON "`object`" would also be valid:

```JSON
{
    "name": "Foo",
    "price": 45.2
}
```

## Declare it as a parameter { #declare-it-as-a-parameter }

🖼, 👉 🏷 🔛 📣 🎻 "`object`" (⚖️ 🐍 `dict`) 💖:

```JSON
{
    "name": "Foo",
    "description": "An optional description",
    "price": 45.2,
    "tax": 3.5
}
```

... `description` & `tax` 📦 (⏮️ 🔢 💲 `None`), 👉 🎻 "`object`" 🔜 ☑:

```JSON
{
    "name": "Foo",
    "price": 45.2
}
```

## 📣 ⚫️ 🔢

🚮 ⚫️ 👆 *➡ 🛠️*, 📣 ⚫️ 🎏 🌌 👆 📣 ➡ & 🔢 🔢:

```Python hl_lines="3  5"
{
    "name": "Bar",
    "description": "The bartenders",
    "price": 62,
    "tax": 20.2
}
```

👫 🔜 🔌 📨.

#### 📊 ⏮️ 🎏 💲 🔢

🚥 📊 ✔️ 🎏 💲 🔢 🕐, 💖 🏬 ⏮️ 🆔 `baz`:

```Python hl_lines="3  5-6"
{
    "name": "Baz",
    "description": None,
    "price": 50.2,
    "tax": 10.5,
    "tags": []
}
```

non-permissive terms added in accord with section 7 apply to the code;
keep intact all notices of the absence of any warranty; and give all
recipients a copy of this License along with the Program.

  You may charge any price or no price for each copy that you convey,
and you may offer support or warranty protection for a fee.

  5. Conveying Modified Source Versions.

  You may convey a work based on the Program, or the modifications to

```Python hl_lines="4  9-12  25-27"
from typing import Union

from fastapi import FastAPI
from pydantic import BaseModel

app = FastAPI()


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


@app.get("/")
def read_root():
    return {"Hello": "World"}


@app.get("/items/{item_id}")
def read_item(item_id: int, q: Union[str, None] = None):

```Python hl_lines="2  7-10  23-25"
from fastapi import FastAPI
from pydantic import BaseModel
from typing import Optional

app = FastAPI()


class Item(BaseModel):
    name: str
    price: float
    is_offer: bool = Optional[None]


@app.get("/")
def read_root():
    return {"Hello": "World"}


@app.get("/items/{item_id}")
def read_item(item_id: int, q: Optional[str] = None):

 * @author ******@****.*** (Geoff Pike)
 */
final class Fingerprint2011 extends AbstractNonStreamingHashFunction {
  static final HashFunction FINGERPRINT_2011 = new Fingerprint2011();

  // Some primes between 2^63 and 2^64 for various uses.
  private static final long K0 = 0xa5b85c5e198ed849L;
  private static final long K1 = 0x8d58ac26afe12e47L;
  private static final long K2 = 0xc47b6e9e3a970ed3L;

    avatarUrl: https://avatars.githubusercontent.com/u/29543316?u=44357eb2a93bccf30fb9d389b8befe94a3d00985&v=4
    url: https://github.com/alixlahuec
- - login: primer-io
    avatarUrl: https://avatars.githubusercontent.com/u/62146168?v=4
    url: https://github.com/primer-io
- - login: upciti
    avatarUrl: https://avatars.githubusercontent.com/u/43346262?v=4
    url: https://github.com/upciti
  - login: giunio-prc

<img src="/img/tutorial/generate-clients/image02.png">

👆 🔜 🤚 ✍ 🚀 📨:

<img src="/img/tutorial/generate-clients/image03.png">

/// tip

👀 ✍ `name` &amp; `price`, 👈 🔬 FastAPI 🈸, `Item` 🏷.

///

👆 🔜 ✔️ ⏸ ❌ 📊 👈 👆 📨:

<img src="/img/tutorial/generate-clients/image04.png">

📨 🎚 🔜 ✔️ ✍:

<img src="/img/tutorial/generate-clients/image05.png">

{* ../../docs_src/body_nested_models/tutorial004_py310.py hl[18] *}

Це означатиме, що  **FastAPI**  очікуватиме тіло запиту такого вигляду:

```JSON
{
    "name": "Foo",
    "description": "The pretender",
    "price": 42.0,
    "tax": 3.2,
    "tags": ["rock", "metal", "bar"],
    "image": {
        "url": "http://example.com/baz.jpg",
        "name": "The Foo live"
    }
}
```