Question

我想使用http客户端类调用api控制器方法，而PostAsync方法引发了Aggregate Exception。我试图编写一个称为PostAsync的异步方法，然后尝试ContinueWith方法，但是没有一个起作用。这是代码：

class Program
{
    private const string apiPath = @"http://localhost:51140";
    private const string param = "/Home/savedocumenttoPath?folderPath=string";

    static void Main(string[] args)
    {
        HttpClient client = new HttpClient();
        client.BaseAddress = new Uri(apiPath);

        // Add an Accept header for JSON format.
        client.DefaultRequestHeaders.Accept.Add(
        new MediaTypeWithQualityHeaderValue("application/json"));

        HttpResponseMessage response = getBack(client);

        Console.WriteLine("{0} ({1})", (int)response.StatusCode, response.ReasonPhrase);

        client.Dispose();
        Console.ReadLine();
    }

    public static HttpResponseMessage getBack(HttpClient client)
    {
         return client.PostAsync(client.BaseAddress + param, null).GetAwaiter().GetResult();
    }
}

这是我要调用的控制器：（我尝试了JsonResult，但也没有用）

[HttpPost]
    public ActionResult saveDocumentToPath(string folderPath)
    {
        try
        {
            if (string.IsNullOrWhiteSpace(folderPath)) throw new NullReferenceException("Invalid Folder!");
            var fullPath = folderPath + "\\";
            if (!System.IO.Directory.Exists(fullPath))
            {
                return new HttpStatusCodeResult(HttpStatusCode.OK, "The specified directory not exists: \n" + fullPath);
            }

            var fileName = "ProjectList_Excel_" + DateTime.Now.Year + DateTime.Now.Month + DateTime.Now.Day;

            var filePathName = fullPath + fileName;
            if (System.IO.File.Exists(filePathName))
            {
                return new HttpStatusCodeResult(HttpStatusCode.OK, "The specified file already exists in the folder: \n" + fileName);
            }
            System.IO.File.WriteAllBytes(filePathName, BL.ExcelExport.GetProjectListExcel());

            return new HttpStatusCodeResult(HttpStatusCode.OK, "File Exported successfully!");
        }
        catch (Exception e)
        {
            return new HttpStatusCodeResult(HttpStatusCode.OK, "Error occured while saving the file" + e.Message);

        }
    }

Answer 1

您可以像这样修改getBack方法。由于端点期望使用简单类型的参数（例如字符串或整数），因此您需要将其包装在FormUrlEncodedContent中。 Dictionary<string, string>中的 folderPath 键与端点参数的名称相对应。

public static HttpResponseMessage getBack(HttpClient client)
{
    var values = new Dictionary<string, string>
    {
        { "folderPath", @"C:\Temp" }
    };

    var content = new FormUrlEncodedContent(values);

    return client.PostAsync("Home/saveDocumentToPath", content).GetAwaiter().GetResult();
}

由于您没有发布json，因此您甚至不需要在客户端中使用client.DefaultRequestHeaders.Accept.Add(new MediaTypeWithQualityHeaderValue("application/json"));。

HttpClient PostAsync方法引发聚合异常

1 个答案: