例如，您可以添加一个额外的媒体类型` image/png` ，声明您的路径操作可以返回JSON对象（媒体类型 `application/json` ）或PNG图像：

{* ../../docs_src/additional_responses/tutorial002.py hl[19:24,28] *}

/// note

- 请注意，您必须直接使用 `FileResponse` 返回图像。

///

/// info

- 除非在 `responses` 参数中明确指定不同的媒体类型，否则**FastAPI**将假定响应与主响应类具有相同的媒体类型（默认为` application/json` ）。
- 但是如果您指定了一个自定义响应类，并将 `None `作为其媒体类型，**FastAPI**将使用 `application/json` 作为具有关联模型的任何其他响应。

///

## 组合信息

                            "description": "Successful Response",
                            "content": {"application/json": {"schema": {}}},
                        },
                        "422": {
                            "description": "Validation Error",
                            "content": {
                                "application/json": {
                                    "schema": {

                    "summary": "Create Item",
                    "operationId": "create_item_items__post",
                    "requestBody": {
                        "content": {
                            "application/json": {
                                "schema": {"$ref": "#/components/schemas/Item"}
                            }
                        },
                        "required": True,
                    },

                            "description": "Successful Response",
                            "content": {"application/json": {"schema": {}}},
                        },
                        "422": {
                            "description": "Validation Error",
                            "content": {
                                "application/json": {
                                    "schema": {

                        "operationId": "create_user_user__post",
                        "requestBody": {
                            "content": {
                                "application/json": {
                                    "schema": {"$ref": "#/components/schemas/UserIn"}
                                }
                            },
                            "required": True,

                            "description": "Successful Response",
                            "content": {"application/json": {"schema": {}}},
                        },
                        "422": {
                            "description": "Validation Error",
                            "content": {
                                "application/json": {
                                    "schema": {

[19511] [INFO] Started server process [19511]
[19511] [INFO] Waiting for application startup.
[19511] [INFO] Application startup complete.
[19513] [INFO] Started server process [19513]
[19513] [INFO] Waiting for application startup.
[19513] [INFO] Application startup complete.
[19514] [INFO] Started server process [19514]
[19514] [INFO] Waiting for application startup.
[19514] [INFO] Application startup complete.
[19515] [INFO] Started server process [19515]

application/vnd.ms-powerpoint=powerpoint\n\
application/vnd.openxmlformats-officedocument.presentationml.presentation=powerpoint\n\
application/vnd.oasis.opendocument.text=odt\n\
application/vnd.oasis.opendocument.spreadsheet=ods\n\
application/vnd.oasis.opendocument.presentation=odp\n\
application/pdf=pdf\n\
application/x-fictionbook+xml=fb2\n\
application/e-pub+zip=epub\n\
application/x-ibooks+zip=ibooks\n\

  - liveness/readiness probes to controller-manager MUST use HTTPS now, and the default port has been changed to 10257.

                            "description": "Successful Response",
                            "content": {"application/json": {"schema": {}}},
                        },
                        "422": {
                            "description": "Validation Error",
                            "content": {
                                "application/json": {
                                    "schema": {