app = FastAPI()


class BaseItem(BaseModel):
    description: str
    type: str


class CarItem(BaseItem):
    type: str = "car"


class PlaneItem(BaseItem):
    type: str = "plane"
    size: int


items = {
    "item1": {"description": "All my friends drive a low rider", "type": "car"},
    "item2": {
        "description": "Music is my aeroplane, it's my aeroplane",
        "type": "plane",

     * of the next non-date character in `input`.
     */
    private fun dateCharacterOffset(
      input: String,
      pos: Int,
      limit: Int,
      invert: Boolean,
    ): Int {
      for (i in pos until limit) {
        val c = input[i].code
        val dateCharacter =
          (
            (

在這個例子裡，`item_id` 被宣告為 `int`。

/// check

這會在你的函式中提供編輯器支援，包括錯誤檢查、自動完成等。

///

## 資料 <dfn title="也稱為：序列化、解析、封送">轉換</dfn> { #data-conversion }

如果你執行這個範例並在瀏覽器開啟 [http://127.0.0.1:8000/items/3](http://127.0.0.1:8000/items/3)，你會看到這樣的回應：

```JSON
{"item_id":3}
```

/// check

注意你的函式接收（並回傳）的值是 `3`，也就是 Python 的 `int`，而不是字串 `"3"`。

from fastapi import FastAPI, Path, Query

app = FastAPI()


@app.get("/items/{item_id}")
async def read_items(
    item_id: int = Path(title="The ID of the item to get"),
    q: str | None = Query(default=None, alias="item-query"),
):
    results = {"item_id": item_id}
    if q:
        results.update({"q": q})

class Item(BaseModel):
    name: str
    description: str | None = None
    price: float
    tax: float | None = None


@app.put("/items/{item_id}")
async def update_item(
    *,
    item_id: int,
    item: Item = Body(
        examples=[
            {
                "name": "Foo",
                "description": "A very nice Item",
                "price": 35.4,
                "tax": 3.2,
            },

        0x6ca4ecb15c5f91e1L,
        0x9f626da15c9625f3L,
        0xe51b38608ef25f57L,
        0x958a324ceb064572L
      };

  public void testVectors() {
    for (int i = 0; i < EXPECTED.length; ++i) {
      byte[] msg = new byte[i];
      for (int j = 0; j < i; ++j) {
        msg[j] = (byte) j;
      }
      assertSip(msg, EXPECTED[i]);
    }
  }

        0x6ca4ecb15c5f91e1L,
        0x9f626da15c9625f3L,
        0xe51b38608ef25f57L,
        0x958a324ceb064572L
      };

  public void testVectors() {
    for (int i = 0; i < EXPECTED.length; ++i) {
      byte[] msg = new byte[i];
      for (int j = 0; j < i; ++j) {
        msg[j] = (byte) j;
      }
      assertSip(msg, EXPECTED[i]);
    }
  }

    }
    final class Splitr extends MapWithIndexSpliterator<Spliterator.OfInt, R, Splitr>
        implements IntConsumer {
      int holder;

      Splitr(Spliterator.OfInt splitr, long index) {
        super(splitr, index);
      }

      @Override
      public void accept(int t) {
        this.holder = t;
      }

      @Override
      public boolean tryAdvance(Consumer<? super R> action) {

    //                                                                          Definition
    //                                                                          ==========
    protected static final int HTTP_BAD_REQUEST = 400;
    protected static final int HTTP_UNAUTHORIZED = 401;

    // ===================================================================================

        UNAUTHORIZED(3),
        /** General failure status. */
        FAILED(9);

        private final int id;

        Status(final int id) {
            this.id = id;
        }

        /**
         * Gets the numeric ID of the status.
         * @return The numeric ID of the status.
         */
        public int getId() {
            return id;
        }
    }

    /**