启用OpenAPI的Azure Function Swagger UI无JSON请求体输入选项

构建启用OpenAPI的HTTP触发类型Azure Function时，通过Postman调用接口传入JSON请求体可正常运行，但Swagger UI中仅显示要求输入name头参数的入口，没有JSON请求体配置区域，界面表现如下：

核心原因是缺少请求体的OpenAPI显式配置。

你确实遗漏了POST接口请求体的声明配置：Swagger UI不会自动解析函数内部手动读取HttpRequest.Body的业务逻辑，只会渲染你通过OpenAPI特性显式声明的参数/请求体结构，按以下步骤修改即可：

• 补充请求体声明特性
  在函数的特性标注块中，添加[OpenApiRequestBody]特性，明确指定请求体的类型为你反序列化使用的FileDetails模型，修改后的完整代码示例如下：

  [FunctionName("ObjectRead")]
  [OpenApiOperation(operationId: "Run", tags: new[] { "name" })]
  [OpenApiSecurity("function_key", SecuritySchemeType.ApiKey, Name = "code", In = OpenApiSecurityLocationType.Query)]
  [OpenApiParameter(name: "name", In = ParameterLocation.Header, Required = true, Type = typeof(string), Description = "The **Name** parameter")]
  // 新增以下请求体声明
  [OpenApiRequestBody(
      contentType: "application/json", 
      bodyType: typeof(FileDetails), 
      Required = true, 
      Description = "文件读取请求参数")]
  [OpenApiResponseWithBody(statusCode: HttpStatusCode.OK, contentType: "application/json", bodyType: typeof(string), Description = "The OK response")]
  public async Task<IActionResult> Run(
      [HttpTrigger(AuthorizationLevel.Function, "post", Route = null)] HttpRequest req)
  {
      _logger.LogInformation($"ObjectRead function triggered at {DateTime.UtcNow.ToString("O")}.");
  
      var requestBody = await new StreamReader(req.Body).ReadToEndAsync().ConfigureAwait(false);
      var data = JsonConvert.DeserializeObject<FileDetails>(requestBody);
      var responseMessage = await _objectReadService.ReadAsync(data.FileName, data.FilePath).ConfigureAwait(false);
  
      _logger.LogInformation($"ObjectRead function completed at {DateTime.UtcNow.ToString("O")}.");
      return responseMessage.Length != 0 ? new FileStreamResult(responseMessage, "application/octet-stream") : new NotFoundObjectResult("Unable to retrieve the file or File not found.");
  }
  

• 校验模型可被解析
  确保你的FileDetails类声明为public，且包含公开无参构造函数，Swagger才能正确读取它的属性结构，自动生成JSON请求体的示例模板。
• 可选优化：直接绑定请求体模型
  你可以省去手动读取请求流反序列化的代码，直接通过[FromBody]特性把请求体绑定到FileDetails类型参数上，写法更简洁，同时OpenAPI扩展的识别兼容性也更好：

  public async Task<IActionResult> Run(
      [HttpTrigger(AuthorizationLevel.Function, "post", Route = null)] HttpRequest req,
      [FromBody] FileDetails data)
  {
      _logger.LogInformation($"ObjectRead function triggered at {DateTime.UtcNow.ToString("O")}.");
      // 直接使用绑定好的data参数即可，无需手动读流反序列化
      var responseMessage = await _objectReadService.ReadAsync(data.FileName, data.FilePath).ConfigureAwait(false);
  
      _logger.LogInformation($"ObjectRead function completed at {DateTime.UtcNow.ToString("O")}.");
      return responseMessage.Length != 0 ? new FileStreamResult(responseMessage, "application/octet-stream") : new NotFoundObjectResult("Unable to retrieve the file or File not found.");
  }
  

修改完成后重启Azure Function项目，刷新Swagger UI页面即可看到JSON请求体的输入区域。

内容的提问来源于stack exchange，提问作者Sandeep Thomas