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

app = FastAPI()


class Item(BaseModel):
    name: str
    price: float
    is_offer: bool | None = None


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


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

多虧了 Pydantic，你可以用標準的 Python 型別來宣告 body。

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

app = FastAPI()


class Item(BaseModel):
    name: str
    price: float
    is_offer: bool | None = None


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


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

 *
 * <p>This class should not be assumed to be universally superior to {@code
 * java.util.LinkedHashMap}. Generally speaking, this class reduces object allocation and memory
 * consumption at the price of moderately increased constant factors of CPU. Only use this class
 * when there is a specific reason to prioritize memory over CPU.
 *
 * @author Louis Wasserman
 */

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

app = FastAPI()


class Item(BaseModel):
    name: str
    price: float
    is_offer: bool | None = None


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


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

* [PyCharm](https://www.jetbrains.com/pycharm/)에서:

![editor support](https://fastapi.tiangolo.com/img/pycharm-completion.png)

이전에 불가능하다고 생각했을 코드에서도 자동 완성을 받을 수 있습니다. 예를 들어, 요청에서 전달되는(중첩될 수도 있는) JSON 본문 내부의 `price` 키 같은 경우입니다.

더 이상 잘못된 키 이름을 입력하거나, 문서 사이를 왔다 갔다 하거나, `username`을 썼는지 `user_name`을 썼는지 찾으려고 위아래로 스크롤할 필요가 없습니다.

### 간결함 { #short }

* in [PyCharm](https://www.jetbrains.com/pycharm/):

![editor support](https://fastapi.tiangolo.com/img/pycharm-completion.png)

You will get completion in code you might even consider impossible before. As for example, the `price` key inside a JSON body (that could have been nested) that comes from a request.

No more typing the wrong key names, coming back and forth between docs, or scrolling up and down to find if you finally used `username` or `user_name`.

* 在 [PyCharm](https://www.jetbrains.com/pycharm/) 中:

![editor support](https://fastapi.tiangolo.com/img/pycharm-completion.png)

你将能进行代码补全，这是在之前你可能曾认为不可能的事。例如，在来自请求 JSON 体（可能是嵌套的）中的键 `price`。

不会再输错键名，来回翻看文档，或者来回滚动寻找你最后使用的 `username` 或者 `user_name`。

### 简洁 { #short }

任何类型都有合理的**默认值**，任何和地方都有可选配置。所有的参数被微调，来满足你的需求，定义成你需要的 API。

但是默认情况下，一切都能**“顺利工作”**。

### 验证 { #validation }

* 在 [PyCharm](https://www.jetbrains.com/pycharm/) 中:

![editor support](https://fastapi.tiangolo.com/img/pycharm-completion.png)

你將能進行程式碼補齊，這是在之前你可能曾認為不可能的事。例如，請求 JSON body（可能是巢狀的）中的鍵 `price`。

這樣比較不會輸錯鍵名，不用來回翻看文件，也不用來回滾動尋找你最後使用的 `username` 或者 `user_name`。

### 簡潔 { #short }

FastAPI 為你提供了**預設值**，讓你不必在初期進行繁瑣的配置，一切都可以自動運作。如果你有更具體的需求，則可以進行調整和自定義，

但預設情況下，一切都「直接可用」。

### 驗證 { #validation }

 *
 * <p>This class should not be assumed to be universally superior to {@code java.util.HashSet}.
 * Generally speaking, this class reduces object allocation and memory consumption at the price of
 * moderately increased constant factors of CPU. Only use this class when there is a specific reason
 * to prioritize memory over CPU.
 *
 * @author Dimitris Andreou
 * @author Jon Noack
 */

   */
  public List<Long> asList() {
    /*
     * Typically we cache this kind of thing, but much repeated use of this view is a performance
     * anti-pattern anyway. If we cache, then everyone pays a price in memory footprint even if
     * they never use this method.
     */
    return new AsList(this);
  }

  private static final class AsList extends AbstractList<Long>