```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):

## Order the parameters as you need, tricks { #order-the-parameters-as-you-need-tricks }

/// tip

This is probably not as important or necessary if you use `Annotated`.

///

Here's a **small trick** that can be handy, but you won't need it often.

If you want to:

* declare the `q` query parameter without a `Query` nor any default value
* declare the path parameter `item_id` using `Path`

```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):

#### Operation

ここでの「オペレーション」とは、HTTPの「メソッド」の1つを指します。

以下のようなものの1つ:

* `POST`
* `GET`
* `PUT`
* `DELETE`

...さらによりエキゾチックなもの:

* `OPTIONS`
* `HEAD`
* `PATCH`
* `TRACE`

HTTPプロトコルでは、これらの「メソッド」の1つ（または複数）を使用して各パスにアクセスできます。

---

APIを構築するときは、通常、これらの特定のHTTPメソッドを使用して特定のアクションを実行します。

通常は次を使用します:

* `POST`: データの作成
* `GET`: データの読み取り
* `PUT`: データの更新

```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):

        assertFalse(emptyIterator.hasNext(), "Empty iterator should have no next element");

        // Note: Standard Iterator would throw NoSuchElementException, but this implementation returns null
        // This is a design choice for this specific implementation
        assertNull(emptyIterator.next(), "This implementation returns null instead of throwing");

        // Verify remove can be called (even though no-op)

```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):

      return new SampleElements<>(
          mapEntry("one", ImmutableSet.of(10000)),
          mapEntry("two", ImmutableSet.of(-2000)),
          mapEntry("three", ImmutableSet.of(300)),
          mapEntry("four", ImmutableSet.of(-40)),
          mapEntry("five", ImmutableSet.of(5)));
    }

    @Override

 * code, running tests, packaging the project, and deploying it. Executing a phase
 * triggers all preceding phases, ensuring that each step of the build process is
 * completed in the correct order. The three main lifecycles in Maven are
 * {@link #DEFAULT default}, {@link #CLEAN clean}, and {@link #SITE site}, with the
 * {@code default} lifecycle being the most commonly used for project builds.
 *
 * @since 4.0.0
 */

そして、それを属性の型として使用することができます:

{* ../../docs_src/body_nested_models/tutorial004.py hl[20] *}

これは **FastAPI** が以下のようなボディを期待することを意味します:

```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"
    }
}
```