"application/json": {
                                "schema": {"$ref": "#/components/schemas/Item"}
                            }
                        },
                        "required": True,
                    },
                }
            }
        },
        "components": {
            "schemas": {
                "Item": {
                    "title": "Item",

                    "summary": "Read Items",
                    "operationId": "read_items_items__get",
                    "security": [{"OAuth2PasswordBearer": []}],
                }
            }
        },
        "components": {
            "securitySchemes": {
                "OAuth2PasswordBearer": {
                    "type": "oauth2",
                    "flows": {"password": {"scopes": {}, "tokenUrl": "token"}},
                }

                    "operationId": "read_current_user_users_me_get",
                    "security": [{"APIKeyQuery": []}],
                }
            }
        },
        "components": {
            "securitySchemes": {
                "APIKeyQuery": {
                    "type": "apiKey",
                    "name": "key",
                    "in": "query",

                    "operationId": "read_current_user_users_me_get",
                    "security": [{"APIKeyHeader": []}],
                }
            }
        },
        "components": {
            "securitySchemes": {
                "APIKeyHeader": {"type": "apiKey", "name": "key", "in": "header"}
            }
        },

                    "operationId": "read_current_user_users_me_get",
                    "security": [{"HTTPBearer": []}],
                }
            }
        },
        "components": {
            "securitySchemes": {
                "HTTPBearer": {
                    "type": "http",
                    "scheme": "bearer",
                    "description": "HTTP Bearer token scheme",

                    "operationId": "read_current_user_users_me_get",
                    "security": [{"HTTPDigest": []}],
                }
            }
        },
        "components": {
            "securitySchemes": {
                "HTTPDigest": {
                    "type": "http",
                    "scheme": "digest",
                    "description": "HTTPDigest scheme",
                }

At first, it didn't have an automatic API documentation web UI, but I knew I could add Swagger UI to it.

It had a dependency injection system. It required pre-registration of components, as other tools discussed above. But still, it was a great feature.

### Dependency Injection

FastAPI bao gồm một hệ thống <abbr title='cũng biết đến như là "components", "resources", "services", "providers"'><strong>Dependency Injection</strong></abbr> vô cùng dễ sử dụng nhưng vô cùng mạnh mẽ.

* Come stabilire **vincoli di validazione** come `maximum_length` o `regex`.
* Un sistema di **<abbr title="detto anche components, resources, providers, services, injectables">Dependency Injection</abbr>** facile da usare e molto potente.
e potente.

**剧透警告**： 教程 - 用户指南中的内容有：

* 对来自不同地方的参数进行声明，如：**请求头**、**cookies**、**form 表单**以及**上传的文件**。
* 如何设置**校验约束**如 `maximum_length` 或者 `regex`。
* 一个强大并易于使用的 **<abbr title="也被称为 components, resources, providers, services, injectables">依赖注入</abbr>** 系统。
* 安全性和身份验证，包括通过 **JWT 令牌**和 **HTTP 基本身份认证**来支持 **OAuth2**。
* 更进阶（但同样简单）的技巧来声明 **多层嵌套 JSON 模型** （借助 Pydantic）。
* 许多额外功能（归功于 Starlette）比如：
    * **WebSockets**