<ol class="breadcrumb float-sm-right">
                            <li class="breadcrumb-item"><la:link href="/admin/badword">
                                <la:message key="labels.bad_word_link_list"/>
                            </la:link></li>
                            <li class="breadcrumb-item active"><la:message
                                    key="labels.bad_word_link_download"/></li>

@dataclass
class Item:
    name: str
    description: Union[str, None] = None


@dataclass
class Author:
    name: str
    items: List[Item] = field(default_factory=list)  # (3)


app = FastAPI()


@app.post("/authors/{author_id}/items/", response_model=Author)  # (4)
async def create_author_items(author_id: str, items: List[Item]):  # (5)

        }
        if (elements.length > 1) {
          /*
           * When a test requests a multiset with duplicates, our plan of
           * "add an extra item 0 to A and an extra item 1 to B" really means
           * "add an extra item 0 to A and B," which isn't what we want.
           */
          if (!Objects.equal(elements[0], elements[1])) {
            multiset2.add(elements[1], 2);
          }
        }

            "type": "value_error.missing"
        }
    ]
}
```

`needy` 是必选参数，因此要在 URL 中设置值：

```
http://127.0.0.1:8000/items/foo-item?needy=sooooneedy
```

……这样就正常了：

```JSON
{
    "item_id": "foo-item",
    "needy": "sooooneedy"
}
```

当然，把一些参数定义为必选，为另一些参数设置默认值，再把其它参数定义为可选，这些操作都是可以的：

//// tab | Python 3.10+

```Python hl_lines="8"

                        <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>
                            <li class="breadcrumb-item"><la:link href="../list/1/?dictId=${f:u(dictId)}">
                                <la:message key="labels.dict_stopwords_list_link"/>

                            <li class="breadcrumb-item"><la:link href="/admin/wizard/">
                                <la:message key="labels.wizard_start_title"/>
                            </la:link></li>
                            <li class="breadcrumb-item"><la:message key="labels.wizard_crawling_config_title"/></li>
                            <li class="breadcrumb-item active"><la:message

                        <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>
                            <li class="breadcrumb-item"><la:link href="../list/1/?dictId=${f:u(dictId)}">
                                <la:message key="labels.dict_mapping_list_link"/>

class Image(BaseModel):
    url: HttpUrl
    name: str


class Item(BaseModel):
    name: str
    description: str | None = None
    price: float
    tax: float | None = None
    tags: set[str] = set()
    images: list[Image] | None = None


class Offer(BaseModel):
    name: str
    description: str | None = None
    price: float
    items: list[Item]


@app.post("/offers/")
async def create_offer(offer: Offer):

                "get": {
                    "tags": ["items"],
                    "summary": "Read Item",
                    "operationId": "read_item_items__item_id__get",
                    "parameters": [
                        {
                            "required": True,
                            "schema": {"title": "Item Id", "type": "string"},
                            "name": "item_id",

	margin-bottom: 4em;
}

.notification {
	font-size: 1.2em;
	margin: 0.2em;
}

.searchButtonBox {
	margin-top: 1em;
}

/* search */

:first-child.list-group-item {
	border-radius: 0px;
}

:last-child.list-group-item {
	border-radius: 0px;
}

#result ol li {
	margin: 1em 0;
}

#result ol li:first-child {
	margin-top: 0;
}

#result .title a:visited {