# 查询参数和字符串校验 { #query-parameters-and-string-validations }

**FastAPI** 允许你为参数声明额外的信息和校验。

让我们以下面的应用为例：

{* ../../docs_src/query_params_str_validations/tutorial001_py310.py hl[7] *}

查询参数 `q` 的类型为 `str | None`，这意味着它是 `str` 类型，但也可以是 `None`。其默认值确实为 `None`，所以 FastAPI 会知道它不是必填的。

/// note | 注意

FastAPI 会因为默认值 `= None` 而知道 `q` 的值不是必填的。

将类型标注为 `str | None` 能让你的编辑器提供更好的辅助和错误检测。

///

## 额外校验 { #additional-validation }

            doColumn("createdTime");
        }

        public void columnHostname() {
            doColumn("hostname");
        }

        public void columnParameters() {
            doColumn("parameters");
        }

        public void columnPassword() {
            doColumn("password");
        }

        public void columnPort() {
            doColumn("port");
        }

   * that conversion is safe.
   *
   * <p>This method is intended to help with usages of type parameters that have {@linkplain
   * ParametricNullness parametric nullness}. If a type parameter instead ranges over only non-null
   * types (or if the type is a non-variable type, like {@code String}), then code should almost

   * that conversion is safe.
   *
   * <p>This method is intended to help with usages of type parameters that have {@linkplain
   * ParametricNullness parametric nullness}. If a type parameter instead ranges over only non-null
   * types (or if the type is a non-variable type, like {@code String}), then code should almost

If it doesn't, it generates them using the utility function at `fastapi.openapi.utils.get_openapi`.

And that function `get_openapi()` receives as parameters:

* `title`: The OpenAPI title, shown in the docs.
* `version`: The version of your API, e.g. `2.5.0`.
* `openapi_version`: The version of the OpenAPI specification used. By default, the latest: `3.1.0`.

            "paths": {
                "/facilities/{facility_id}": {
                    "get": {
                        "operationId": "get_facility_facilities__facility_id__get",
                        "parameters": [
                            {
                                "in": "path",
                                "name": "facility_id",
                                "required": True,

                "/messages": {
                    "post": {
                        "summary": "Create Message",
                        "operationId": "create_message_messages_post",
                        "parameters": [
                            {
                                "name": "input_message",
                                "in": "query",
                                "required": True,

import org.codelibs.fess.suggest.request.RequestBuilder;
import org.opensearch.transport.client.Client;

/**
 * Builder class for constructing {@link SuggestRequest} instances.
 * This builder provides methods to set various parameters for the suggest request.
 */
public class SuggestRequestBuilder extends RequestBuilder<SuggestRequest, SuggestResponse> {
    /**
     * Constructor for SuggestRequestBuilder.
     * @param client The OpenSearch client.

# 標頭參數模型 { #header-parameter-models }

如果你有一組相關的標頭參數，可以建立一個 Pydantic 模型來宣告它們。

這能讓你在多處重複使用該模型，並一次性為所有參數宣告驗證與中繼資料。😎

/// note | 注意

自 FastAPI 版本 `0.115.0` 起支援。🤓

///

## 以 Pydantic 模型宣告標頭參數 { #header-parameters-with-a-pydantic-model }

在 Pydantic 模型中宣告你需要的標頭參數，然後將參數宣告為 `Header`：

{* ../../docs_src/header_param_models/tutorial001_an_py310.py hl[9:14,18] *}

FastAPI 會從請求的標頭為每個欄位擷取資料，並交給你已定義的 Pydantic 模型實例。

        return requestBody;
    }

    @Override
    protected Map<String, Object> getUpdateMap() {
        final Map<String, Object> updateMap = new HashMap<>();
        updateMap.put("parameters", "new_parameters=aaa");
        return updateMap;
    }

    @Test
    void crudTest() {
        testCreate();
        testRead();
        testUpdate();
        testDelete();
    }