如何提取http az函数响应以在自定义中间件中使用？

Question

用例：我想使用自定义中间件对 http 触发字符串响应进行最后一刻的修改。

我将自定义中间件编写为：

internal sealed class MyCustomMiddleware : IFunctionsWorkerMiddleware
{
  public async Task Invoke(FunctionContext context, FunctionExecutionDelegate next)
  {
    await next(context); //returns "Hello"

    //I want modify response to becomes "Hello World"
  }
}

我将自定义中间件注册为：

var host = new HostBuilder()
          .ConfigureFunctionsWorkerDefaults(worker =>
          {
             worker.UseMiddleware<MyCustomMiddleware>();
          })
          .Build();

     host.Run();

函数执行后无法提取响应字符串“Hello”。我尝试使用 GetHttpResponseData() 但它返回 null。

context.GetHttpResponseData().Body

Answer 1

我尝试了下面的代码来提取Http触发的Azure函数的响应并在自定义中间件中修改其上下文。

• 感谢@Sil提供代码。

自定义中间件：

 public sealed class MyCustomMiddleware : IFunctionsWorkerMiddleware
 {
     public async Task Invoke(FunctionContext context, FunctionExecutionDelegate next)
     {
        // Fetching the Http Azure function response
         var req = await context.GetHttpRequestDataAsync();

        // Modifying the response
         var res = req!.CreateResponse();
         await res.WriteStringAsync("Function response changed");
         context.GetInvocationResult().Value = res;
     }
 }

程序.cs：

var host = new HostBuilder()
    .ConfigureFunctionsWorkerDefaults(worker =>
    {
        worker.UseMiddleware<MyCustomMiddleware>();
    })
    .ConfigureServices(services =>
    {
        services.AddApplicationInsightsTelemetryWorkerService();
        services.ConfigureFunctionsApplicationInsights();
    })
    .Build();

host.Run();

控制台输出：

Azure Functions Core Tools
Core Tools Version:       4.0.5455 Commit hash: N/A  (64-bit)
Function Runtime Version: 4.27.5.21554

[2023-12-13T12:15:21.065Z] Found C:\Users\<user>\Source\Repos\FunctionApp18\FunctionApp18\FunctionApp18.csproj. Using for user secrets file configuration.
[2023-12-13T12:15:31.028Z] Azure Functions .NET Worker (PID: 26252) initialized in debug mode. Waiting for debugger to attach...
[2023-12-13T12:15:31.229Z] Worker process started and initialized.

Functions:

        Function1: [GET,POST] http://localhost:7299/api/Function1

For detailed output, run func with --verbose flag.
[2023-12-13T12:15:36.296Z] Host lock lease acquired by instance ID '000000000000000000000000XXXXXXC'.
[2023-12-13T12:15:44.167Z] Executing 'Functions.Function1' (Reason='This function was programmatically called via the host APIs.', Id=7f684090-4XXXXXXXXXXXXe-1f825fe62a1f)
[2023-12-13T12:15:44.489Z] Executed 'Functions.Function1' (Succeeded, Id=7f684090-46a6-XXXXXXXXXXXXXX-1f825fe62a1f, Duration=363ms)

初步回应：

修改后的回复：