StringBuilder buffer = new StringBuilder(256);

        buffer.append("Missing:").append(LS);
        buffer.append("----------").append(LS);

        int counter = 0;

        for (Artifact artifact : artifacts) {
            String message = (++counter) + ") " + artifact.getId();

            buffer.append(constructMissingArtifactMessage(
                    message,

                    .filter(p -> p.getFileName().toString().endsWith(".pom"))
                    .collect(Collectors.toList());
        }
    }

    @Benchmark
    public int readWithStax(AdditionState state) throws IOException, XMLStreamException {
        int i = 0;
        for (Path pom : state.poms) {
            try (InputStream is = Files.newInputStream(pom)) {
                MavenStaxReader reader = new MavenStaxReader();

	"gorm.io/gorm/schema"
)

var schemaCache = &sync.Map{}

func TestConvertToCreateValues_DestType_Slice(t *testing.T) {
	type user struct {
		ID    int `gorm:"primaryKey"`
		Name  string
		Email string `gorm:"default:(-)"`
		Age   int    `gorm:"default:(-)"`
	}

	s, err := schema.Parse(&user{}, schemaCache, schema.NamingStrategy{})
	if err != nil {
		t.Errorf("parse schema error: %v, is not expected", err)

}
```

当然，把一些参数定义为必选，为另一些参数设置默认值，再把其它参数定义为可选，这些操作都是可以的：

{* ../../docs_src/query_params/tutorial006_py310.py hl[8] *}

本例中有 3 个查询参数：

* `needy`，必选的 `str` 类型参数
* `skip`，默认值为 `0` 的 `int` 类型参数
* `limit`，可选的 `int` 类型参数

/// tip | 提示

还可以像在[路径参数](path-params.md#_8){.internal-link target=_blank} 中那样使用 `Enum`。

class ReviewNode(BaseModel):
    author: Author | None = None
    state: str


class Reviews(BaseModel):
    nodes: list[ReviewNode]


class PullRequestNode(BaseModel):
    number: int
    labels: Labels
    author: Author | None = None
    title: str
    createdAt: datetime
    lastEditedAt: datetime | None = None
    updatedAt: datetime | None = None
    state: str
    reviews: Reviews

    price: float = Field(examples=[35.4])
    tax: float | None = Field(default=None, examples=[3.2])


@app.put("/items/{item_id}")
async def update_item(item_id: int, item: Item):
    results = {"item_id": item_id, "item": item}

from typing import Union

from fastapi import FastAPI

app = FastAPI()


@app.get("/users/{user_id}/items/{item_id}")
async def read_user_item(
    user_id: int, item_id: str, q: Union[str, None] = None, short: bool = False
):
    item = {"item_id": item_id, "owner_id": user_id}
    if q:
        item.update({"q": q})
    if not short:
        item.update(

                return o;
            }
        }
        return Optional.empty();
    }

    protected Optional<List<String>> collectListIfPresentOrEmpty(Function<O, Optional<List<String>>> getter) {
        int had = 0;
        ArrayList<String> items = new ArrayList<>();
        for (O option : options) {
            Optional<List<String>> o = getter.apply(option);
            if (o.isPresent()) {
                had++;

@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 {"item_id": item_id, "q": q}


@app.put("/items/{item_id}")
def update_item(item_id: int, item: Item):
    return {"item_name": item.name, "item_id": item_id}
```

服务器将会自动重载（因为在上面的步骤中你向 `uvicorn` 命令添加了 `--reload` 选项）。

    price: float
    tax: Union[float, None] = None
    tags: set[str] = set()
    images: Union[list[Image], None] = None


@app.put("/items/{item_id}")
async def update_item(item_id: int, item: Item):
    results = {"item_id": item_id, "item": item}