HttpClient PostAsync 方法抛出聚合异常

Question

我想使用 http 客户端 class 调用 api 控制器方法，但 PostAsync 方法引发了聚合异常。我尝试编写一个调用 PostAsync 的异步方法并尝试使用 ContinueWith 方法，但没有一个起作用。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();
    }
}

这里是我想调用的控制器：（我试过 JsonResult 但还是不行）

[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

您可以像这样修改您的 getBack 方法。由于您的端点需要简单类型的参数（例如字符串或整数），因此您需要将其包装在 FormUrlEncodedContent 中。 folderPath键在Dictionary<string, string>对应端点的参数名称。

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();
}

您甚至不需要在您的客户端中使用 client.DefaultRequestHeaders.Accept.Add(new MediaTypeWithQualityHeaderValue("application/json"));，因为您没有发布 json。

HttpClient PostAsync 方法抛出聚合异常

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