## 总结 { #recap }

你能够以与[查询参数和字符串校验](query-params-str-validations.md)相同的方式使用 `Query`、`Path`（以及其他你还没见过的类）声明元数据和字符串校验。

而且你还可以声明数值校验：

* `gt`：大于（`g`reater `t`han）
* `ge`：大于等于（`g`reater than or `e`qual）
* `lt`：小于（`l`ess `t`han）
* `le`：小于等于（`l`ess than or `e`qual）

/// info | 信息

`Query`、`Path` 以及你后面会看到的其他类，都是一个通用 `Param` 类的子类。

它们都共享相同的参数，用于你已看到的额外校验和元数据。

///

{"attributes":{"description":"","kibanaSavedObjectMeta":{"searchSourceJSON":"{\"query\":{\"query\":\"\",\"language\":\"kuery\"},\"filter\":[],\"indexRefName\":\"kibanaSavedObjectMeta.searchSourceJSON.index\"}"},"title":"search-query-counts-per-sec","uiStateJSON":"{}","version":1,"visState":"{\"title\":\"search-query-counts-per-sec\",\"type\":\"histogram\",\"params\":{\"type\":\"histogram\",\"grid\":{\"categoryLines\":false},\"categoryAxes\":[{\"...

from dirty_equals import IsPartialDict
from fastapi import Cookie, FastAPI, Header, Query
from fastapi.testclient import TestClient
from pydantic import BaseModel, Field

app = FastAPI()


class Model(BaseModel):
    param: str = Field(alias="param_alias")


@app.get("/query")
async def query_model(data: Model = Query()):
    return {"param": data.param}


@app.get("/header")
async def header_model(data: Model = Header()):

from fastapi import Body, FastAPI, Query
from fastapi.testclient import TestClient

app = FastAPI()


@app.get("/query")
def read_query(q: str | None):
    return q


@app.get("/explicit-query")
def read_explicit_query(q: str | None = Query()):
    return q


@app.post("/body-embed")
def send_body_embed(b: str | None = Body(embed=True)):
    return b


client = TestClient(app)

        }

        return resultBuf.toString();
    }

    /**
     * Sets the query builder for filtering documents.
     *
     * @param queryBuilder the query builder to filter documents
     * @return this UpdateLabelJob instance for method chaining
     */
    public UpdateLabelJob query(final QueryBuilder queryBuilder) {
        this.queryBuilder = queryBuilder;
        return this;
    }

    /**
     * Performs a search operation using the specified query and parameters.
     *
     * @param query the search query string
     * @param params the search request parameters
     * @param userBean the optional user bean for access control
     * @return the search result containing documents and metadata
     */
    @Override

func parsePreSignV4(query url.Values, region string, stype serviceType) (psv preSignValues, aec APIErrorCode) {
	// verify whether the required query params exist.
	aec = doesV4PresignParamsExist(query)
	if aec != ErrNone {
		return psv, aec
	}

	// Verify if the query algorithm is supported or not.
	if query.Get(xhttp.AmzAlgorithm) != signV4Algorithm {

 * list is a single empty string: `[""]`.
 *
 * ### Query
 *
 * The query is optional: it can be null, empty, or non-empty. For many HTTP URLs the query string
 * is subdivided into a collection of name-value parameters. This class offers methods to set the
 * query as the single string, or as individual name-value parameters. With name-value parameters

        });

        String query = ComponentUtil.getQueryStringBuilder().params(params).sortField(params.getSort()).build();
        List<Map<String, Object>> documentItems;
        try {
            documentItems = searchInternal(query, params, userBean);
        } catch (final InvalidQueryException e) {
            if (logger.isDebugEnabled()) {
                logger.debug("Invalid query: {}", query, e);
            }

`Field` 的工作方式和 `Query`、`Path`、`Body` 相同，参数也相同。

/// note | 技术细节

实际上，`Query`、`Path` 以及你接下来会看到的其它对象，会创建公共 `Param` 类的子类的对象，而 `Param` 本身是 Pydantic 中 `FieldInfo` 的子类。

Pydantic 的 `Field` 返回也是 `FieldInfo` 的类实例。

`Body` 直接返回的也是 `FieldInfo` 的子类的对象。后文还会介绍一些 `Body` 的子类。

注意，从 `fastapi` 导入的 `Query`、`Path` 等对象实际上都是返回特殊类的函数。

///

/// tip | 提示