## 定义 `Form` 参数

创建表单（`Form`）参数的方式与 `Body` 和 `Query` 一样：

```Python hl_lines="7"
{!../../docs_src/request_forms/tutorial001.py!}
```

例如，OAuth2 规范的 "密码流" 模式规定要通过表单字段发送 `username` 和 `password`。

<abbr title="specification">该规范</abbr>要求字段必须命名为 `username` 和 `password`，并通过表单字段发送，不能用 JSON。

使用 `Form` 可以声明与 `Body` （及 `Query`、`Path`、`Cookie`）相同的元数据和验证。

/// info | "说明"

`Form` 是直接继承自 `Body` 的类。

///

/// tip | "提示"

    public void insert(final User user) {
        chains().of(stream -> stream.forEach(c -> c.update(user)));
    }

    public boolean changePassword(final String username, final String password) {
        return chains().get(stream -> stream.allMatch(c -> c.changePassword(username, password)));
    }

    public void delete(final User user) {
        chains().of(stream -> stream.forEach(c -> c.delete(user)));
    }

from pydantic import BaseModel

app = FastAPI()


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


class User(BaseModel):
    username: str
    full_name: str | None = None


@app.put("/items/{item_id}")
async def update_item(
    item_id: int, item: Item, user: User, importance: Annotated[int, Body()]
):

                + createdTime + ", hostname=" + hostname + ", parameters=" + parameters + ", port=" + port + ", protocolScheme="
                + protocolScheme + ", updatedBy=" + updatedBy + ", updatedTime=" + updatedTime + ", username=" + username + ", webConfigId="
                + webConfigId + ", docMeta=" + docMeta + "]";
    }

from pydantic import BaseModel

app = FastAPI()


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


class User(BaseModel):
    username: str
    full_name: str | None = None


@app.put("/items/{item_id}")
async def update_item(
    *,
    item_id: int,
    item: Item,
    user: User,
    importance: int = Body(gt=0),

  static final class BasicAuthInterceptor implements Interceptor {
    private final String credentials;
    private final String host;

    BasicAuthInterceptor(String host, String username, String password) {
      this.credentials = Credentials.basic(username, password);
      this.host = host;
    }

    @Override public Response intercept(Chain chain) throws IOException {
      Request request = chain.request();

								</source>
							</sources>
						</mapping>
						<mapping>
							<directory>${packaging.fess.var.dir}</directory>
							<filemode>755</filemode>
							<username>${packaging.fess.user}</username>
							<groupname>${packaging.fess.group}</groupname>
						</mapping>
						<!-- bin -->
						<mapping>
							<directory>${packaging.fess.bin.dir}</directory>
							<filemode>755</filemode>

Para lidar com isso, primeiramente nós convertemos o `username` e o `password` para `bytes`, codificando-os com UTF-8.

Então nós podemos utilizar o `secrets.compare_digest()` para garantir que o `credentials.username` é `"stanleyjobson"`, e que o `credentials.password` é `"swordfish"`.

//// tab | Python 3.9+

```Python hl_lines="1  12-24"

        final String username = systemHelper.getUsername();
        runtime.registerData("username", username);
        runtime.registerData("editableUser", fessLoginAssist.getSavedUserBean().map(FessUserBean::isEditable).orElse(false));
        runtime.registerData("adminUser", fessConfig.isAdminUser(username) || fessLoginAssist.getSavedUserBean()

                                        <th><la:message
                                                key="labels.file_auth_username"/></th>
                                        <td>${f:h(username)}<la:hidden property="username"/></td>
                                    </tr>
                                    <tr>
                                        <th><la:message