Question

异步执行REST调用和进程响应。

System.AggregateException: One or more errors occurred. ---> System.AggregateException: One or more errors occurred. ---> System.ArgumentException: An item with the same key has already been added.
   at System.ThrowHelper.ThrowArgumentException(ExceptionResource resource)
   at System.Collections.Generic.Dictionary`2.Insert(TKey key, TValue value, Boolean add)
   at System.Net.Http.Headers.HttpHeaders.AddHeaderToStore(String name, HeaderStoreItemInfo info)
   at System.Net.Http.Headers.HttpHeaders.CreateAndAddHeaderToStore(String name)
   at System.Net.Http.Headers.HttpHeaders.GetOrCreateHeaderInfo(String name, Boolean parseRawValues)
   at System.Net.Http.Headers.HttpHeaders.SetParsedValue(String name, Object value)
   at System.Net.Http.Headers.HttpContentHeaders.get_ContentLength()
   at System.Net.Http.HttpClientHandler.PrepareAndStartContentUpload(RequestState state)
   --- End of inner exception stack trace ---
   at System.Threading.Tasks.Task.ThrowIfExceptional(Boolean includeTaskCanceledExceptions)
   at System.Threading.Tasks.Task`1.GetResultCore(Boolean waitCompletionNotification)
   at System.Threading.Tasks.Task`1.get_Result()
   System.Threading.Tasks.ContinuationResultTaskFromResultTask`2.InnerInvoke()
   at System.Threading.Tasks.Task.Execute()
   --- End of inner exception stack trace ---
   at System.Threading.Tasks.Task.ThrowIfExceptional(Boolean includeTaskCanceledExceptions)
   at System.Threading.Tasks.Task`1.GetResultCore(Boolean waitCompletionNotification)
   at System.Threading.Tasks.Task`1.get_Result()

代码：

var resultTask = base.WrapCallWithLogging(requestUri, task, method, sw, content);

resultTask.ContinueWith(t =>
{
    // Do something 
    GetMessage(); //access the variable content
};

return resultTask;

我的理解是我们得到了这个例外，因为由于某种原因，标题被创建了两次。这可能是异步任务的问题。谁能指出正确的文件？

base.WrapCallWithLogging()方法：

protected virtual Task<HttpResponseMessage> WrapCallWithLogging(RestUri requestUri, Task<HttpResponseMessage> task, HttpMethod method, Stopwatch sw, HttpContent content = null)
{
    var uriTemplate = requestUri.BuildFullTemplateString();
    Logger.DebugFormat("Making http '{0}' call to '{1}'", method, uriTemplate);
    return task.ContinueWith(r =>
    {
        var result = r.Result;
        sw.Stop();
        Logger.DebugFormat("Ending http '{0}' call to '{1}' with status code {2} in {3} ms",
           method, 
           uriTemplate.ToString(),
           result == null ? HttpStatusCode.InternalServerError : result.StatusCode,
           sw.ElapsedMilliseconds);

        return result;
    });
}

Answer 1

异常堆栈跟踪将您带到此代码行：

var result = r.Result;

r这是第一个片段中的task：

var resultTask = base.WrapCallWithLogging(requestUri, task, method, sw, content);

所以，就你没有提供它的初始化而言，很难说它有什么问题，但你应该调查它的代码。你说错误信息是

异步任务导致异常：System.ArgumentException：已添加具有相同键的项

可以在此处找到与解决方案类似的错误：

An item with the same key has already been added

最有可能的是，您的模型包含两次相同的属性。也许您正在使用new来隐藏基本属性解决方案是覆盖属性或使用其他名称如果您分享您的模型，我们将能够详细说明。

异步任务导致异常：System.ArgumentException：已添加具有相同键的项

1 个答案: