c# - 如何从第二个 API 调用返回相同的状态代码

Question

我有一个调用第二个 API 的 ASP.NET Core API。

如果第二个 API 出现错误，我会在我的服务层抛出一个异常:

var response = await httpClient.SendAsync(request); //call second API

if (!response.IsSuccessStatusCode)
{
    //return HTTP response with StatusCode = X, if response.StatusCode == X
    throw new HttpRequestException(await response.Content.ReadAsStringAsync()); 
    //this always returns 400
}

我如何抛出一个异常，该异常将返回具有与第二次 API 调用相同的状态代码的响应？

如果我使用 HttpRequestException，它将始终返回 400，即使 response 对象有 StatusCode = 500。

编辑:第一个 API 端点如下所示:

            public async Task<ActionResult<HttpResponseMessage>> CreateTenancy([FromBody]TenancyRequest tenancy)
            {
                //Make some calls...
                return Created(string.Empty, new { TenancyID = newTenancyExternalId });
            }

第二个 API 端点如下所示:

    [HttpPost]
    public IHttpActionResult CreateTenancy([FromBody]TenancyDTO tenancyDTO)
    {    
        var tenancy = GetTenancy();    
        return Created(string.Empty, tenancy);
    }

我试过使用 throw new HttpResponseException(response); 但这会删除描述性异常消息，有效负载最终如下所示:

{
    "Code": 500,
    "CorrelationId": "2df08016-e5e3-434a-9136-6824495ed907",
    "DateUtc": "2020-01-30T02:02:48.4428978Z",
    "ErrorMessage": "Processing of the HTTP request resulted in an exception. Please see the HTTP response returned by the 'Response' property of this exception for details.",
    "ErrorType": "InternalServerError"
}

我想在原始负载中保留 ErrorMessage 值:

{
    "Code": 400,
    "CorrelationId": "ff9466b4-8c80-4dab-b5d7-9bba1355a567",
    "DateUtc": "2020-01-30T03:05:13.2397543Z",
    "ErrorMessage": "\"Specified cast is not valid.\"",
    "ErrorType": "BadRequest"
}

最终目标是返回:

{
    "Code": 500,
    "CorrelationId": "ff9466b4-8c80-4dab-b5d7-9bba1355a567",
    "DateUtc": "2020-01-30T03:05:13.2397543Z",
    "ErrorMessage": "\"Specified cast is not valid.\"",
    "ErrorType": "InternalServerError"
}

Answer 1

我尝试了一些简单的操作，例如更改 API 端点的返回类型并在出现错误时按原样返回对象。否则，构建您自己的 HttpResponseMessage 并返回它。下面的代码片段使用文本，但您可以使用序列化器序列化其他内容(如果有的话)。

public async Task<HttpResponseMessage> Test(string str)
{
    var httpClient = new HttpClient();
    var request = new HttpRequestMessage(HttpMethod.Get, $"myAPI that returns different errors 400, 404, 500 etc based on str");

    var response = await httpClient.SendAsync(request);
    if (!response.IsSuccessStatusCode)
        return response;

    // do something else
    return new HttpResponseMessage(System.Net.HttpStatusCode.OK) { Content = new StringContent("Your Text here") };
}

---

Other approach of using Filters

使用 IHttpActionResult 作为返回类型的另一种方法是，您可以使用过滤器使所有 HttpResponseMessages 符合 IHttpActionResult。

过滤器:创建一个单独的 cs 文件并使用此过滤器定义。

public class CustomObjectResponse : IHttpActionResult
{
    private readonly object _obj;

    public CustomObjectResponse(object obj)
    {
        _obj = obj;
    }

    public Task<HttpResponseMessage> ExecuteAsync(CancellationToken cancellationToken)
    {
        HttpResponseMessage response = _obj as HttpResponseMessage;
        return Task.FromResult(response);
    }
}

在您的 API 中，您可以像这样使用您的过滤器，

public async Task<IHttpActionResult> Test(string str)
{
    var httpClient = new HttpClient();
    var request = new HttpRequestMessage(HttpMethod.Get, $"http://localhost:4500/api/capacity/update-mnemonics/?mnemonic_to_update={str}");

    var response = await httpClient.SendAsync(request);
    if (!response.IsSuccessStatusCode)
        return new CustomObjectResponse(response);

    // Other Code here

    // Return Other objects 
    KeyValuePair<string, string> testClass = new KeyValuePair<string, string>("Sheldon", "Cooper" );
    return new OkWithObjectResult(testClass);

    // Or Return Standard HttpResponseMessage
    return Ok();

}