You can define arbitrarily deeply nested models:

{* ../../docs_src/body_nested_models/tutorial007_py310.py hl[7,12,18,21,25] *}

/// info

Notice how `Offer` has a list of `Item`s, which in turn have an optional list of `Image`s

///

## Bodies of pure lists { #bodies-of-pure-lists }

Documentation = "https://fastapi.tiangolo.com/"
Repository = "https://github.com/fastapi/fastapi"
Issues = "https://github.com/fastapi/fastapi/issues"
Changelog = "https://fastapi.tiangolo.com/release-notes/"

[project.optional-dependencies]
standard = [
    "fastapi-cli[standard] >=0.0.8",
    # For the test client
    "httpx >=0.23.0,<1.0.0",
    # For templates
    "jinja2 >=3.1.5",
    # For forms and file uploads

import org.codelibs.fess.util.ComponentUtil;
import org.codelibs.fess.util.DocumentUtil;
import org.codelibs.fess.util.QueryResponseList;
import org.dbflute.optional.OptionalEntity;
import org.dbflute.optional.OptionalThing;
import org.lastaflute.web.util.LaRequestUtil;
import org.opensearch.action.update.UpdateRequest;
import org.opensearch.script.Script;

	"github.com/minio/minio/internal/s3select/sql"
	"github.com/minio/pkg/v3/env"
	"github.com/minio/simdjson-go"
	"github.com/pierrec/lz4/v4"
)

type recordReader interface {
	// Read a record.
	// dst is optional but will be used if valid.
	Read(dst sql.Record) (sql.Record, error)
	Close() error
}

const (
	csvFormat     = "csv"
	jsonFormat    = "json"
	parquetFormat = "parquet"
)

 *    augmented by certificates private to an organization or service.
 *
 * ### Client Authentication
 *
 * This is authentication of the client by the server during the TLS handshake. Client
 * authentication is optional.
 *
 * To perform client authentication:
 *
 *  * The client's handshake certificates must have a [held certificate][HeldCertificate] (a

        // Test that empty args (except for goal) work correctly
        String[] args = {"apply"};
        CommonsCliUpgradeOptions options = CommonsCliUpgradeOptions.parse(args);

        // None of the optional flags should be present
        assertFalse(options.plugins().isPresent(), "--plugins should not be present by default");
        assertFalse(options.all().isPresent(), "--all should not be present by default");

import org.codelibs.fess.opensearch.user.exbhv.UserBhv;
import org.codelibs.fess.opensearch.user.exentity.User;
import org.codelibs.fess.util.ComponentUtil;
import org.dbflute.cbean.result.PagingResultBean;
import org.dbflute.optional.OptionalEntity;

import jakarta.annotation.Resource;

/**
 * Service class for managing user operations in the Fess search system.

Это не является ограничением **FastAPI**, это часть протокола HTTP.

///

## Необязательная загрузка файлов { #optional-file-upload }

Вы можете сделать загрузку файла необязательной, используя стандартные аннотации типов и установив значение по умолчанию `None`:

{* ../../docs_src/request_files/tutorial001_02_an_py310.py hl[9,17] *}

import org.codelibs.fess.rank.fusion.SearchResult.SearchResultBuilder;
import org.codelibs.fess.unit.UnitFessTestCase;
import org.codelibs.fess.util.QueryResponseList;
import org.dbflute.optional.OptionalThing;
import org.junit.jupiter.api.Test;

/**
 * Edge case tests for RankFusionProcessor.
 * Tests boundary conditions, empty states, and error scenarios.
 */

{* ../../docs_src/body/tutorial001_py310.py hl[5:9] *}

与声明查询参数一样，包含默认值的模型属性是可选的，否则就是必选的。把默认值设为 `None` 可使其变为可选。

例如，上述模型声明如下 JSON "object"（即 Python `dict`）：

```JSON
{
    "name": "Foo",
    "description": "An optional description",
    "price": 45.2,
    "tax": 3.5
}
```

...由于 `description` 和 `tax` 是可选的（默认值为 `None`），下面的 JSON "object" 也有效：

```JSON
{
    "name": "Foo",
    "price": 45.2
}
```