SL3 / SL4-新DataServiceCollection期间出现Ado.Net数据服务错误 <T> （queryResponse）

Question

大家好，我在SL项目（VS2010）中有两个功能几乎可以完成相同的操作，但是其中一个会引发错误，而另一个则不会。 它似乎与预测有关，但我不确定最好的解决方法。

起作用的功能是...

public void LoadAllChunksExpandAll(DataHelperReturnHandler handler, string orderby)
    {
        DataServiceCollection<CmsChunk> data = null;

        DataServiceQuery<CmsChunk> theQuery = _dataservice
            .CmsChunks
            .Expand("CmsItemState")
            .AddQueryOption("$orderby", orderby);

        theQuery.BeginExecute(
            delegate(IAsyncResult asyncResult)
            {
                _callback_dispatcher.BeginInvoke(
                        () =>
                        {
                            try
                            {
                                DataServiceQuery<CmsChunk> query = asyncResult.AsyncState as DataServiceQuery<CmsChunk>;
                                if (query != null)
                                {
                                    //create a tracked DataServiceCollection from the result of the asynchronous query.
                                    QueryOperationResponse<CmsChunk> queryResponse =
                                        query.EndExecute(asyncResult) as QueryOperationResponse<CmsChunk>;
                                    data = new DataServiceCollection<CmsChunk>(queryResponse);

                                    handler(data);
                                }
                            }
                            catch
                            {
                                handler(data);
                            }
                        }
                    );
            },
            theQuery
        );
    }

这将编译并按预期运行。 一个非常非常相似的功能（如下所示）失败了...

             public void LoadAllPagesExpandAll(DataHelperReturnHandler handler, string orderby)
    {
        DataServiceCollection<CmsPage> data = null;

        DataServiceQuery<CmsPage> theQuery = _dataservice
            .CmsPages
            .Expand("CmsChildPages")
            .Expand("CmsParentPage")
            .Expand("CmsItemState")
            .AddQueryOption("$orderby", orderby);

        theQuery.BeginExecute(
            delegate(IAsyncResult asyncResult)
            {
                _callback_dispatcher.BeginInvoke(
                        () =>
                        {
                            try
                            {
                                DataServiceQuery<CmsPage> query = asyncResult.AsyncState as DataServiceQuery<CmsPage>;
                                if (query != null)
                                {
                                    //create a tracked DataServiceCollection from the result of the asynchronous query.
                                    QueryOperationResponse<CmsPage> queryResponse = query.EndExecute(asyncResult) as QueryOperationResponse<CmsPage>;
                                    data = new DataServiceCollection<CmsPage>(queryResponse);

                                    handler(data);
                                }
                            }
                            catch
                            {
                                handler(data);
                            }
                        }
                    );
            },
            theQuery
        );
    }

显然，问题在于涉及自我引用关系的扩展投影（页面可以包含其他页面）。 这是在SL4或SL3下，使用ADONETDataServices SL3更新CTP3。

我乐于接受任何解决方法或指向粘性信息的指示，对错误的Google搜索会导致两次点击，但我都无法破译它们。

简短错误是“无法将项目添加到集合中。当DataServiceContext跟踪DataServiceCollection中的项目时，在将项目加载到集合中之前无法添加新项目。”

完整的错误是...

捕获了System.Reflection.TargetInvocationException消息=调用的目标已抛出异常。 StackTrace：在System.RuntimeMethodHandle._InvokeMethodFast（IRuntimeMethodInfo方法，对象目标，Object []参数，SignatureStruct＆sig，MethodAttributes方法属性，RuntimeType类型所有者）在System.Reflection.RuntimeMethodInfo.Invoke（对象obj，BindingFlags invokeAttr，活页夹活页夹，对象[] System.Reflection.RuntimeMethodInfo.Invoke（Object obj，BindingFlags invokeAttr，活页夹活页夹，Object []参数，CultureInfo文化）的System.Reflection.MethodBase.Invoke（Object obj，Object []参数）中的参数，CultureInfo文化，布尔skipVisibilityChecks） ），位于System.Data.Services.Client.AtomMaterializer.ApplyItemsToCollection（AtomEntry条目，ClientProperty属性，IEnumerable项，位于System.Data.Services.Client.ClientType.ClientProperty.SetValue（对象实例，对象值，字符串propertyName，布尔值allowAdd） Uri nextLink，位于System.Data.Services.Client.AtomMaterializer.ApplyFeedToCollection（AtomEntry条目，ClientProperty的ProjectionPlancontinuationPlan） 属性，位于System.Data.Services.Client.AtomMaterializer.MaterializeResolvedEntry（AtomEntry条目，布尔值包含链接）的System.Data.Services.Client.AtomMaterializer.Materialize（AtomEntry条目，类型ExpectedEntryType，布尔值includeLinks） System.Data.Services.Client.AtomMaterializerInvoker.DirectMaterializePlan（对象Materializer，对象条目，类型ExpectedEntryType）在System.Data.Services处的System.Data.Services.Client.AtomMaterializer.DirectMaterializePlan（AtomMaterializer实体化程序，AtomEntry条目，类型ExpectedEntryType）。在System.Data.Services.Client.AtomMaterializer.Read（）在System.Data.Services.Client.MaterializeAtom.MoveNextInternal（）在System.Data.Services处的Client.ProjectionPlan.Run（AtomMaterializer实现器，AtomEntry条目，类型ExpectedType）。 System.Linq.Enumerable.d__b1的1.MoveNext() at System.Data.Services.Client.DataServiceCollection处的1.MoveNext() at System.Data.Services.Client.DataServiceCollection 1.InternalLoadCollection（IEnumerable 1 items) at System.Data.Services.Client.DataServiceCollection 1 items) at System.Data.Services.Client.DataServiceCollection 1..ctor（ 1 items) at System.Data.Services.Client.DataServiceCollection 1.StartTracking（DataServiceContext上下文，IEnumerable 1 items, String entitySet, Func函数2实体更改，函数2 collectionChanged) at System.Data.Services.Client.DataServiceCollection IEnumerable 1 items, TrackingMode trackingMode, String entitySetName, Func 2 EntityChangedCallback，Func 2 collectionChangedCallback) at System.Data.Services.Client.DataServiceCollection （ 2 collectionChangedCallback) at System.Data.Services.Client.DataServiceCollection 1..ctor（IEnumerable 1 items) at Phinli.Dashboard.Silverlight.Helpers.DataHelper.<>c__DisplayClass44.<>c__DisplayClass46.<LoadAllPagesExpandAll>b__43() InnerException: System.InvalidOperationException Message=An item could not be added to the collection. When items in a DataServiceCollection are tracked by the DataServiceContext, new items cannot be added before items have been loaded into the collection. StackTrace: at System.Data.Services.Client.DataServiceCollection 1 items) at Phinli.Dashboard.Silverlight.Helpers.DataHelper.<>c__DisplayClass44.<>c__DisplayClass46.<LoadAllPagesExpandAll>b__43() InnerException: System.InvalidOperationException Message=An item could not be added to the collection. When items in a DataServiceCollection are tracked by the DataServiceContext, new items cannot be added before items have been loaded into the collection. StackTrace: at System.Data.Services.Client.DataServiceCollection 1 items) at Phinli.Dashboard.Silverlight.Helpers.DataHelper.<>c__DisplayClass44.<>c__DisplayClass46.<LoadAllPagesExpandAll>b__43() InnerException: System.InvalidOperationException Message=An item could not be added to the collection. When items in a DataServiceCollection are tracked by the DataServiceContext, new items cannot be added before items have been loaded into the collection. StackTrace: at System.Data.Services.Client.DataServiceCollection 1.InsertItem（Int32索引，T项目）位于System.Collections.ObjectModel.Collection`1.Add（T项目）InnerException：

谢谢你的帮助！

Answer 1

这听起来有点像数据服务中的错误。

我将跟进数据服务团队，并给您答复。

由于周末可能要花几天时间。

亚历克斯·詹姆斯

数据服务经理

Answer 2

我认为这里的问题是DataServiceCollection无法将下载的实体添加到顶级CMSPage类型的相应DataServiceCollection属性中。我们做了一些特殊的说明以确保DataServiceCollection仅在开始跟踪某些对象之后才能使用。 我稍后将对此进行调查，同时尝试以下代码：

public void LoadAllPagesExpandAll(DataHelperReturnHandler handler, string orderby) 
{ 
  DataServiceCollection<CmsPage> data = new   DataServiceCollection<CmsPage>( _dataservice );

  DataServiceQuery<CmsPage> theQuery = _dataservice 
      .CmsPages 
      .Expand("CmsChildPages") 
      .Expand("CmsParentPage") 
      .Expand("CmsItemState") 
      .AddQueryOption("$orderby", orderby); 

  theQuery.BeginExecute( 
      delegate(IAsyncResult asyncResult) 
      { 
    _callback_dispatcher.BeginInvoke( 
      () => 
      { 
          try 
          { 
        DataServiceQuery<CmsPage> query = asyncResult.AsyncState as DataServiceQuery<CmsPage>; 
        if (query != null) 
        { 
            //create a tracked DataServiceCollection from the result of the asynchronous query. 
            QueryOperationResponse<CmsPage> queryResponse = query.EndExecute(asyncResult) as QueryOperationResponse<CmsPage>; 
            data.Load(queryResponse); 

            handler(data); 
        } 
          } 
          catch 
          { 
        handler(data); 
          } 
      } 
        ); 
      }, 
      theQuery 
  ); 
}