],
      "msg": "Input should be a valid integer, unable to parse string as an integer",
      "input": "foo"
    }
  ]
}
```

这是因为路径参数 `item_id` 的值（`"foo"`）的类型不是 `int`。

值的类型不是 `int` 而是浮点数（`float`）时也会显示同样的错误，比如： [http://127.0.0.1:8000/items/4.2](http://127.0.0.1:8000/items/4.2)

/// check | 检查

**FastAPI** 使用同样的 Python 类型声明实现了数据校验。

注意，上面的错误清晰地指出了未通过校验的具体位置。

这在开发调试与 API 交互的代码时非常有用。

///

from fastapi import FastAPI
from fastapi.sse import EventSourceResponse
from pydantic import BaseModel

app = FastAPI()


class Item(BaseModel):
    name: str
    price: float


@app.get("/items/stream", response_class=EventSourceResponse)
async def stream_items() -> AsyncIterable[Item]:
    yield Item(name="Plumbus", price=32.99)
    yield Item(name="Portal Gun", price=999.99)
```

                            <la:message key="labels.dict_stopwords_title"/>
                        </h1>
                    </div>
                    <div class="col-sm-6">
                        <ol class="breadcrumb float-sm-right">
                            <li class="breadcrumb-item"><la:link href="/admin/dict">
                                <la:message key="labels.dict_list_link"/>
                            </la:link></li>

					<div class="row mb-2">
						<div class="col-sm-6">
							<h1>
								<la:message key="labels.storage_configuration" />
							</h1>
						</div>
						<div class="col-sm-6">
							<ol class="breadcrumb float-sm-right">
								<li class="breadcrumb-item"><la:link href="/admin/storage/">
										<la:message key="labels.crud_link_list" />
									</la:link></li>

                            <la:message key="labels.dict_stemmeroverride_title"/>
                        </h1>
                    </div>
                    <div class="col-sm-6">
                        <ol class="breadcrumb float-sm-right">
                            <li class="breadcrumb-item"><la:link href="/admin/dict">
                                <la:message key="labels.dict_list_link"/>
                            </la:link></li>

         * Sets the weight for the request data.
         *
         * @param weight the weight to set
         * @return the current RequestDataContext instance
         */
        public RequestDataContext weight(final float weight) {
            data.setWeight(weight);
            return this;
        }

        /**
         * Builds and returns the constructed RequestData object.
         *

                            <la:message key="labels.dict_list_title"/>
                        </h1>
                    </div>
                    <div class="col-sm-6">
                        <ol class="breadcrumb float-sm-right">
                            <li><la:message key="labels.dict_list_link"/></li>
                        </ol>
                    </div>
                </div>
            </div>
        </div>

                            <la:message key="labels.wizard_start_crawling_title"/>
                        </h1>
                    </div>
                    <div class="col-sm-6">
                        <ol class="breadcrumb float-sm-right">
                            <li class="breadcrumb-item"><la:link href="/admin/wizard/">
                                <la:message key="labels.wizard_start_title"/>
                            </la:link></li>

            final Pair<String, Float> pair = new Pair<>();
            final String[] values = s.split(":");
            if (values.length == 1) {
                pair.setFirst(values[0].trim());
                pair.setSecond(1.0f);
            } else if (values.length > 1) {
                pair.setFirst(values[0]);
                pair.setSecond(Float.parseFloat(values[1]));
            } else {

    //                                                                        ============
    public static class SearchRequestParams {

        private Boolean explain;

        private Float minScore;

        private String preference;

        private String routing;

        private String searchType;

        private long timeoutInMillis = -1;

        private Boolean version;