HttpClient PostAsync方法引發聚合異常

Question

我想使用http客戶端類調用api控制器方法，而PostAsync方法引發了Aggregate Exception。 我試圖編寫一個稱為PostAsync的異步方法，然后嘗試ContinueWith方法，但是沒有一個起作用。 這是代碼：

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();
    }
}

這是我要調用的控制器：（我嘗試了JsonResult，但也無法正常工作）

[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

您可以像這樣修改getBack方法。 由於端點期望的參數是簡單類型（例如，字符串或整數），因此需要將其包裝在FormUrlEncodedContent 。 Dictionary<string, string>的folderPath鍵與端點參數的名稱相對應。

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();
}

您甚至不需要client.DefaultRequestHeaders.Accept.Add(new MediaTypeWithQualityHeaderValue("application/json")); 在您的客戶端中，因為您沒有發布json。