return HttpResponseMessage 作为 .Net Core 2.2 中的 IActionResult 的正确方法

Question

在 .Net Core 2.2 中。我正在创建一个 API 控制器，它根据负载将请求路由到另一个 Http 端点。

  [Route("api/v1")]
  public class RoutesController : Controller
  {
      [HttpPost]
      [Route("routes")]
      public async Task<IActionResult> Routes([FromBody]JObject request)
      {
                 
        var httpClient = new HttpClient();

        // here based on request httpCLient will make `POST` or `GET` or `PUT` request
        // and returns `Task<HttpResponseMessage>`. Lets assume its making `GET` 
        // call

       Task<HttpResponseMessage> response = await
         httpClient.GetAsync(request["resource"]);
            
       /*  ??? what is the correct way to return response as `IActionResult`*/
      }        
  }

基于 post我可以做到

        return StatusCode((int)response.StatusCode, response);

但是我不确定发送 HttpResponseMessage 因为 ObjectResult 是正确的方式。

我还想确保内容协商有效。

Answer 1

您可以创建一个自定义的 IActionResult 来包装传输逻辑。

public async Task<IActionResult> Routes([FromBody]JObject request)
{
    var httpClient = new HttpClient();

    HttpResponseMessage response = await httpClient.GetAsync("");

    // Here we ask the framework to dispose the response object a the end of the user resquest
    this.HttpContext.Response.RegisterForDispose(response);

    return new HttpResponseMessageResult(response);
}

public class HttpResponseMessageResult : IActionResult
{
    private readonly HttpResponseMessage _responseMessage;

    public HttpResponseMessageResult(HttpResponseMessage responseMessage)
    {
        _responseMessage = responseMessage; // could add throw if null
    }

    public async Task ExecuteResultAsync(ActionContext context)
    {
        context.HttpContext.Response.StatusCode = (int)_responseMessage.StatusCode;

        foreach (var header in _responseMessage.Headers)
        {
            context.HttpContext.Response.Headers.TryAdd(header.Key, new StringValues(header.Value.ToArray()));
        }

        if(_responseMessage.Content != null)
        {
            using (var stream = await _responseMessage.Content.ReadAsStreamAsync())
            {
                await stream.CopyToAsync(context.HttpContext.Response.Body);
                await context.HttpContext.Response.Body.FlushAsync();
            }
        }
    }
}

Answer 2

public class HttpResponseMessageResult : IActionResult
{
    private readonly HttpResponseMessage _responseMessage;

    public HttpResponseMessageResult(HttpResponseMessage responseMessage)
    {
        _responseMessage = responseMessage; // could add throw if null
    }

    public async Task ExecuteResultAsync(ActionContext context)
    {
        var response = context.HttpContext.Response;


        if (_responseMessage == null)
        {
            var message = "Response message cannot be null";

            throw new InvalidOperationException(message);
        }

        using (_responseMessage)
        {
            response.StatusCode = (int)_responseMessage.StatusCode;

            var responseFeature = context.HttpContext.Features.Get<IHttpResponseFeature>();
            if (responseFeature != null)
            {
                responseFeature.ReasonPhrase = _responseMessage.ReasonPhrase;
            }

            var responseHeaders = _responseMessage.Headers;

            // Ignore the Transfer-Encoding header if it is just "chunked".
            // We let the host decide about whether the response should be chunked or not.
            if (responseHeaders.TransferEncodingChunked == true &&
                responseHeaders.TransferEncoding.Count == 1)
            {
                responseHeaders.TransferEncoding.Clear();
            }

            foreach (var header in responseHeaders)
            {
                response.Headers.Append(header.Key, header.Value.ToArray());
            }

            if (_responseMessage.Content != null)
            {
                var contentHeaders = _responseMessage.Content.Headers;

                // Copy the response content headers only after ensuring they are complete.
                // We ask for Content-Length first because HttpContent lazily computes this
                // and only afterwards writes the value into the content headers.
                var unused = contentHeaders.ContentLength;

                foreach (var header in contentHeaders)
                {
                    response.Headers.Append(header.Key, header.Value.ToArray());
                }

                await _responseMessage.Content.CopyToAsync(response.Body);
            }
        }
    }

Answer 3

ASP.NET 核心有 return 对象 RedirectResult 来重定向调用者。

Answer 4

只需将响应包装在 Ok() 操作中 return 类型：

return Ok(response)

因此您的代码将类似于：

[Route("api/v1")]
public class RoutesController : Controller
{
    [HttpPost]
    [Route("routes")]
    public async Task<IActionResult> Routes([FromBody]JObject request)
    {

      var httpClient = new HttpClient();
   
      Task<HttpResponseMessage> response = await httpClient.GetAsync(request["resource"]);

      return Ok(response);
    }        
}

更多信息在这里：https://docs.microsoft.com/en-us/aspnet/core/web-api/action-return-types?view=aspnetcore-3.1

return HttpResponseMessage 作为 .Net Core 2.2 中的 IActionResult 的正确方法

Correct way to return HttpResponseMessage as IActionResult in .Net Core 2.2

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