**FastAPI** は [**Pydantic**](https://docs.pydantic.dev/) と完全に互換性があり（かつそれに基づいています）。そのため、手元の Pydantic の追加コードも動作します。

Pydantic に基づく外部ライブラリ（データベース用の <abbr title="Object-Relational Mapper - オブジェクト関係マッパー">ORM</abbr>、<abbr title="Object-Document Mapper - オブジェクトドキュメントマッパー">ODM</abbr> など）も含まれます。

これは、すべてが自動的に検証されるため、多くの場合、リクエストから取得したオブジェクトを **そのままデータベースに** 渡せることを意味します。

逆方向も同様で、多くの場合、データベースから取得したオブジェクトを **そのままクライアントに** 渡せます。

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   1. Definitions.

      "License" shall mean the terms and conditions for use, reproduction,
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      "Legal Entity" shall mean the union of the acting entity and all

   TERMS AND CONDITIONS FOR USE, REPRODUCTION, AND DISTRIBUTION

   1. Definitions.

      "License" shall mean the terms and conditions for use, reproduction,
      and distribution as defined by Sections 1 through 9 of this document.

      "Licensor" shall mean the copyright owner or entity authorized by
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      "Legal Entity" shall mean the union of the acting entity and all

   TERMS AND CONDITIONS FOR USE, REPRODUCTION, AND DISTRIBUTION

   1. Definitions.

      "License" shall mean the terms and conditions for use, reproduction,
      and distribution as defined by Sections 1 through 9 of this document.

      "Licensor" shall mean the copyright owner or entity authorized by
      the copyright owner that is granting the License.

      "Legal Entity" shall mean the union of the acting entity and all

   TERMS AND CONDITIONS FOR USE, REPRODUCTION, AND DISTRIBUTION

   1. Definitions.

      "License" shall mean the terms and conditions for use, reproduction,
      and distribution as defined by Sections 1 through 9 of this document.

      "Licensor" shall mean the copyright owner or entity authorized by
      the copyright owner that is granting the License.

      "Legal Entity" shall mean the union of the acting entity and all

   TERMS AND CONDITIONS FOR USE, REPRODUCTION, AND DISTRIBUTION

   1. Definitions.

      "License" shall mean the terms and conditions for use, reproduction,
      and distribution as defined by Sections 1 through 9 of this document.

      "Licensor" shall mean the copyright owner or entity authorized by
      the copyright owner that is granting the License.

      "Legal Entity" shall mean the union of the acting entity and all

@app.post("/items/")
async def create_item(item: Item, project_id: Annotated[int, Query(...)]): ...
```

## Return Type or Response Model

When possible, include a return type. It will be used to validate, filter, document, and serialize the response.

```python
from fastapi import FastAPI
from pydantic import BaseModel

app = FastAPI()


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

        private void testSetup(Snippet snippet) {
            if (lastDocsPath == snippet.path) {
                throw new InvalidUserDataException("$snippet: wasn't first. TESTSETUP can only be used in the first snippet of a document.")
            }
            setupCurrent(snippet)
            current.println('---')
            current.println("setup:")
            if (snippet.setup != null) {
                setup(snippet)
            }

   TERMS AND CONDITIONS FOR USE, REPRODUCTION, AND DISTRIBUTION

   1. Definitions.

      "License" shall mean the terms and conditions for use, reproduction,
      and distribution as defined by Sections 1 through 9 of this document.

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      the copyright owner that is granting the License.

      "Legal Entity" shall mean the union of the acting entity and all

    }

    /**
     * Deletes documents from the specified index based on the given query.
     *
     * @param client the OpenSearch client to use for executing the query and delete operations
     * @param settings the settings for the suggest feature, including timeouts and scroll settings
     * @param index the name of the index from which documents should be deleted