在我的 Xamarin Forms 应用中，我使用WCF数据服务更新，如下所示：
try
{
SRef.MyEntities entities = new SRef.MyEntities(new Uri(App.BaseURL));
DataServiceQuery query = (DataServiceQuery) entities.DataEntry.First();
query.BeginExecute((result) =>
{
try
{
query.BeginExecute((result) =>
{
try
{
var actData = query.EndExecute(result).FirstOrDefault();
if (actData != null)
{
actData.Info = "Info2";
entities.UpdateObject(actData);
entities.BeginSaveChanges((result2) =>
{
try
{
entities.EndSaveChanges(result2);
}
catch (Exception ex2)
{
Alert("Error: " + ex2.Message);
}
}, null);
}
}
catch (Exception ex1)
{
Alert("Error: " + ex1.Message);
}
}, query);
}
catch (Exception ex)
{
Alert("Error: " + ex.Message);
}
});
运行时，我收到以下异常无法捕获且 EndSaveChanges 无法运行：
---- DEBUG ASSERTION FAILED ----
03-16 09:59:22.057 D: DllImport attempting to load: '/system/lib/liblog.so'.
[0:] ---- DEBUG ASSERTION FAILED ----
D: DllImport loaded library '/system/lib/liblog.so'.
D: DllImport searching in: '/system/lib/liblog.so' ('/system/lib/liblog.so').
D: Searching for '__android_log_print'.
D: Probing '__android_log_print'.
D: Found as '__android_log_print'.
I: ---- DEBUG ASSERTION FAILED ----
[0:]
---- Assert Short Message ----
I: ---- Assert Short Message ----
[0:]
Expected DateTimeOffset to be a UTC value.
[0:] Expected DateTimeOffset to be a UTC value.
I: Expected DateTimeOffset to be a UTC value.
[0:]
at System.Diagnostics.DefaultTraceListener.Fail(System.String message, System.String detailMessage)
I: at System.Diagnostics.DefaultTraceListener.Fail(System.String message, System.String detailMessage)
at System.Diagnostics.TraceListener.Fail(System.String message)
at System.Diagnostics.DefaultTraceListener.Fail(System.String message)
at System.Diagnostics.TraceImpl.Fail(System.String message)
at System.Diagnostics.TraceImpl.Assert(Boolean condition, System.String message)
at System.Diagnostics.Debug.Assert(Boolean condition, System.String message)
at Microsoft.Data.OData.PlatformHelper.ConvertDateTimeToStringInternal(DateTime dateTime)
at Microsoft.Data.OData.PlatformHelper.ConvertDateTimeToString(DateTime dateTime)
at Microsoft.Data.OData.Atom.ODataAtomConvert.ToString(DateTime dt)
at Microsoft.Data.OData.AtomValueUtils.TryConvertPrimitiveToString(System.Object value, System.String ByRef result)
at Microsoft.Data.OData.AtomValueUtils.ConvertPrimitiveToString(System.Object value)
at Microsoft.Data.OData.AtomValueUtils.WritePrimitiveValue(System.Xml.XmlWriter writer, System.Object value)
at Microsoft.Data.OData.Atom.ODataAtomPropertyAndValueSerializer.WritePrimitiveValue
I: at System.Diagnostics.TraceListener.Fail(System.String message)
[0:] at System.Diagnostics.DefaultTraceListener.Fail(System.String message, System.String detailMessage)
at System.Diagnostics.TraceListener.Fail(System.String message)
at System.Diagnostics.DefaultTraceListener.Fail(System.String message)
at System.Diagnostics.TraceImpl.Fail(System.String message)
at System.Diagnostics.TraceImpl.Assert(Boolean condition, System.String message)
at System.Diagnostics.Debug.Assert(Boolean condition, System.String message)
at Microsoft.Data.OData.PlatformHelper.ConvertDateTimeToStringInternal(DateTime dateTime)
at Microsoft.Data.OData.PlatformHelper.ConvertDateTimeToString(DateTime dateTime)
at Microsoft.Data.OData.Atom.ODataAtomConvert.ToString(DateTime dt)
at Microsoft.Data.OData.AtomValueUtils.TryConvertPrimitiveToString(System.Object value, System.String ByRef result)
at Microsoft.Data.OData.AtomValueUtils.ConvertPrimitiveToString(System.Object value)
at Microsoft.Data.OData.AtomValueUtils.WritePrimitiveValue(System.Xml.XmlWriter writer, System.Object value)
at Microsoft.Data.OData.Atom.ODataAtomPropertyAndValueSerializer.WritePrimitiveValue(System.Object value, Microsoft.Data.OData.CollectionWithoutExpectedTypeValidator collectionValidator, IEdmTypeReference expectedTypeReference, Microsoft.Data.OData.SerializationTypeNameAnnotation typeNameAnnotation)
at Microsoft.Data.OData.Atom.ODataAtomPropertyAndValueSerializer.WriteProperty(Microsoft.Data.OData.ODataProperty property, IEdmStructuredType owningType, Boolean isTopLevel, Boolean isWritingCollection, System.Action beforePropertyAction, Microsoft.Data.OData.Atom.EpmValueCache epmValueCache, Microsoft.Data.OData.Metadata.EpmSourcePathSegment epmParentSourcePathSegment, Microsoft.Data.OData.DuplicatePropertyNamesChecker duplicatePropertyNamesChecker, Microsoft.Data.OData.ProjectedPropertiesAnnotation projectedProperties)
at Microsoft.Data.OData.Atom.ODataAtomPropertyAndValueSerializer.WriteProperties(IEdmStructuredType owningType, IEnumerable`1 cachedProperties, Boolean isWritingCollection, System.Action beforePropertiesAction, System.Action afterPropertiesAction, Microsoft.Data.OData.DuplicatePropertyNamesChecker duplicatePropertyNamesChecker, Microsoft.Data.OData.Atom.EpmValueCache epmValueCache, Microsoft.Data.OData.Metadata.EpmSourcePathSegment epmSourcePathSegment, Microsoft.Data.OData.ProjectedPropertiesAnnotation projectedProperties)
at Microsoft.Data.OData.Atom.ODataAtomWriter.WriteEntryContent(Microsoft.Data.OData.ODataEntry entry, IEdmEntityType entryType, Microsoft.Data.OData.Atom.EntryPropertiesValueCache propertiesValueCache, Microsoft.Data.OData.Metadata.EpmSourcePathSegment rootSourcePathSegment, Microsoft.Data.OData.ProjectedPropertiesAnnotation projectedProperties)
at Microsoft.Data.OData.Atom.ODataAtomWriter.EndEntry(Microsoft.Data.OData.ODataEntry entry)
at Microsoft.Data.OData.ODataWriterCore.b__16()
at Microsoft.Data.OData.ODataWriterCore.InterceptException(System.Action action)
at Microsoft.Data.OData.ODataWriterCore.WriteEndImplementation()
at Microsoft.Data.OData.ODataWriterCore.WriteEnd()
at System.Data.Services.Client.ODataWriterWrapper.WriteEnd(Microsoft.Data.OData.ODataEntry entry, System.Object entity)
at System.Data.Services.Client.Serializer.WriteEntry(System.Data.Services.Client.EntityDescriptor entityDescriptor, IEnumerable`1 relatedLinks, System.Data.Services.Client.ODataRequestMessageWrapper requestMessage)
at System.Data.Services.Client.BaseSaveResult.CreateRequestData(System.Data.Services.Client.EntityDescriptor entityDescriptor, System.Data.Services.Client.ODataRequestMessageWrapper requestMessage)
at System.Data.Services.Client.BaseSaveResult.CreateChangeData(Int32 index, System.Data.Services.Client.ODataRequestMessageWrapper requestMessage)
at System.Data.Services.Client.SaveResult.CreateNonBatchChangeData(Int32 index, System.Data.Services.Client.ODataRequestMessageWrapper requestMessage)
at System.Data.Services.Client.SaveResult.BeginCreateNextChange()
at System.Data.Services.Client.DataServiceContext.BeginSaveChanges(SaveChangesOptions options, System.AsyncCallback callback, System.Object state)
at System.Data.Services.Client.DataServiceContext.BeginSaveChanges(System.AsyncCallback callback, System.Object state)
at StefaniaXamarin.ViewModel.PaciensAdatokViewModel+c__DisplayClass4.b__1(IAsyncResult result)
at System.Data.Services.Client.BaseAsyncResult.HandleCompleted()
at System.Data.Services.Client.QueryResult.HandleCompleted(System.Data.Services.Client.PerRequest pereq)
at System.Data.Services.Client.QueryResult.AsyncEndRead(IAsyncResult asyncResult)
at System.Data.Services.Client.BaseAsyncResult.PostInvokeAsync(IAsyncResult asyncResult, System.AsyncCallback callback)
at System.Data.Services.Client.BaseAsyncResult.InvokeAsync(System.Data.Services.Client.AsyncAction asyncAction, System.Byte[] buffer, Int32 offset, Int32 length, System.AsyncCallback callback, System.Object state)
at System.Data.Services.Client.QueryResult.ReadResponseStream(System.Data.Services.Client.AsyncStateBag asyncStateBag)
at System.Data.Services.Client.QueryResult.AsyncEndRead(IAsyncResult asyncResult)
at System.Data.Services.Client.BaseAsyncResult+c__DisplayClass2.b__1(IAsyncResult asyncResult)
at System.Net.SimpleAsyncResult+c__AnonStorey0.m__0(System.Net.SimpleAsyncResult result)
at System.Net.SimpleAsyncResult.DoCallback_internal()
at System.Net.WebAsyncResult.DoCallback()
at System.Net.WebConnectionStream.ReadCallbackWrapper(IAsyncResult r)
(System.Object value, Microsoft.Data.OData.CollectionWithoutExpectedTypeValidator collectionValidator, IEdmTypeReference expectedTypeReference, Microsoft.Data.OData.SerializationTypeNameAnnotation typeNameAnnotation)
at Microsoft.Data.OData.Atom.ODataAtomPropertyAndValueSerializer.WriteProperty(Microsoft.Data.OData.ODataProperty property, IEdmStructuredType owningType, Boolean isTopLevel, Boolean isWritingCollection, System.Action beforePropertyAction, Microsoft.Data.OData.Atom.EpmValueCache epmValueCache, Microsoft.Data.OData.Metadata.EpmSourcePathSegment epmParentSourcePathSegment, Microsoft.Data.OData.DuplicatePropertyNamesChecker duplicatePropertyNamesChecker, Microsoft.Data.OData.ProjectedPropertiesAnnotation projectedProperties)
at Microsoft.Data.OData.Atom.ODataAtomPropertyAndValueSerializer.WriteProperties(IEdmStructuredType owningType, IEnumerable`1 cachedProperties, Boolean isWritingCollection, System.Action beforePropertiesAction, System.Action afterPropertiesAction, Microsoft.Data.OData.Dupl
I: at System.Diagnostics.DefaultTraceListener.Fail(System.String message)
icatePropertyNamesChecker duplicatePropertyNamesChecker, Microsoft.Data.OData.Atom.EpmValueCache epmValueCache, Microsoft.Data.OData.Metadata.EpmSourcePathSegment epmSourcePathSegment, Microsoft.Data.OData.ProjectedPropertiesAnnotation projectedProperties)
at Microsoft.Data.OData.Atom.ODataAtomWriter.WriteEntryContent(Microsoft.Data.OData.ODataEntry entry, IEdmEntityType entryType, Microsoft.Data.OData.Atom.EntryPropertiesValueCache propertiesValueCache, Microsoft.Data.OData.Metadata.EpmSourcePathSegment rootSourcePathSegment, Microsoft.Data.OData.ProjectedPropertiesAnnotation projectedProperties)
at Microsoft.Data.OData.Atom.ODataAtomWriter.EndEntry(Microsoft.Data.OData.ODataEntry entry)
at Microsoft.Data.OData.ODataWriterCore.b__16()
at Microsoft.Data.OData.ODataWriterCore.InterceptException(System.Action action)
at Microsoft.Data.OData.ODataWriterCore.WriteEndImplementation()
at Microsoft.Data.OData.ODataWriterCore.WriteEnd()
at System.Data.Services.Client.OData
I: at System.Diagnostics.TraceImpl.Fail(System.String message)
WriterWrapper.WriteEnd(Microsoft.Data.OData.ODataEntry entry, System.Object entity)
at System.Data.Services.Client.Serializer.WriteEntry(System.Data.Services.Client.EntityDescriptor entityDescriptor, IEnumerable`1 relatedLinks, System.Data.Services.Client.ODataRequestMessageWrapper requestMessage)
at System.Data.Services.Client.BaseSaveResult.CreateRequestData(System.Data.Services.Client.EntityDescriptor entityDescriptor, System.Data.Services.Client.ODataRequestMessageWrapper requestMessage)
at System.Data.Services.Client.BaseSaveResult.CreateChangeData(Int32 index, System.Data.Services.Client.ODataRequestMessageWrapper requestMessage)
at System.Data.Services.Client.SaveResult.CreateNonBatchChangeData(Int32 index, System.Data.Services.Client.ODataRequestMessageWrapper requestMessage)
at System.Data.Services.Client.SaveResult.BeginCreateNextChange()
at System.Data.Services.Client.DataServiceContext.BeginSaveChanges(SaveChangesOptions options, System.AsyncCallback callback, System.Object state
I: at System.Diagnostics.TraceImpl.Assert(Boolean condition, System.String message)
)
at System.Data.Services.Client.DataServiceContext.BeginSaveChanges(System.AsyncCallback callback, System.Object state)
at StefaniaXamarin.ViewModel.PaciensAdatokViewModel+c__DisplayClass4.b__1(IAsyncResult result)
at System.Data.Services.Client.BaseAsyncResult.HandleCompleted()
at System.Data.Services.Client.QueryResult.HandleCompleted(System.Data.Services.Client.PerRequest pereq)
at System.Data.Services.Client.QueryResult.AsyncEndRead(IAsyncResult asyncResult)
at System.Data.Services.Client.BaseAsyncResult.PostInvokeAsync(IAsyncResult asyncResult, System.AsyncCallback callback)
at System.Data.Services.Client.BaseAsyncResult.InvokeAsync(System.Data.Services.Client.AsyncAction asyncAction, System.Byte[] buffer, Int32 offset, Int32 length, System.AsyncCallback callback, System.Object state)
at System.Data.Services.Client.QueryResult.ReadResponseStream(System.Data.Services.Client.AsyncStateBag asyncStateBag)
at System.Data.Services.Client.QueryResult.AsyncEndRead(IAsyncResul
I: at System.Diagnostics.Debug.Assert(Boolean condition, System.String message)
t asyncResult)
at System.Data.Services.Client.BaseAsyncResult+c__DisplayClass2.b__1(IAsyncResult asyncResult)
at System.Net.SimpleAsyncResult+c__AnonStorey0.m__0(System.Net.SimpleAsyncResult result)
at System.Net.SimpleAsyncResult.DoCallback_internal()
at System.Net.WebAsyncResult.DoCallback()
at System.Net.WebConnectionStream.ReadCallbackWrapper(IAsyncResult r)
I: at Microsoft.Data.OData.PlatformHelper.ConvertDateTimeToStringInternal(DateTime dateTime)
I: at Microsoft.Data.OData.PlatformHelper.ConvertDateTimeToString(DateTime dateTime)
I: at Microsoft.Data.OData.Atom.ODataAtomConvert.ToString(DateTime dt)
I: at Microsoft.Data.OData.AtomValueUtils.TryConvertPrimitiveToString(System.Object value, System.String ByRef result)
I: at Microsoft.Data.OData.AtomValueUtils.ConvertPrimitiveToString(System.Object value)
I: at Microsoft.Data.OData.AtomValueUtils.WritePrimitiveValue(System.Xml.XmlWriter writer, System.Object value)
I: at Microsoft.Data.OData.Atom.ODataAtomPropertyAndValueSerializer.WritePrimitiveValue(System.Object value, Microsoft.Data.OData.CollectionWithoutExpectedTypeValidator collectionValidator, IEdmTypeReference expectedTypeReference, Microsoft.Data.OData.SerializationTypeNameAnnotation typeNameAnnotation)
I: at Microsoft.Data.OData.Atom.ODataAtomPropertyAndValueSerializer.WriteProperty(Microsoft.Data.OData.ODataProperty property, IEdmStructuredType owningType, Boolean isTopLevel, Boolean isWritingCollection, System.Action beforePropertyAction, Microsoft.Data.OData.Atom.EpmValueCache epmValueCache, Microsoft.Data.OData.Metadata.EpmSourcePathSegment epmParentSourcePathSegment, Microsoft.Data.OData.DuplicatePropertyNamesChecker duplicatePropertyNamesChecker, Microsoft.Data.OData.ProjectedPropertiesAnnotation projectedProperties)
I: at Microsoft.Data.OData.Atom.ODataAtomPropertyAndValueSerializer.WriteProperties(IEdmStructuredType owningType, IEnumerable`1 cachedProperties, Boolean isWritingCollection, System.Action beforePropertiesAction, System.Action afterPropertiesAction, Microsoft.Data.OData.DuplicatePropertyNamesChecker duplicatePropertyNamesChecker, Microsoft.Data.OData.Atom.EpmValueCache epmValueCache, Microsoft.Data.OData.Metadata.EpmSourcePathSegment epmSourcePathSegment, Microsoft.Data.OData.ProjectedPropertiesAnnotation projectedProperties)
I: at Microsoft.Data.OData.Atom.ODataAtomWriter.WriteEntryContent(Microsoft.Data.OData.ODataEntry entry, IEdmEntityType entryType, Microsoft.Data.OData.Atom.EntryPropertiesValueCache propertiesValueCache, Microsoft.Data.OData.Metadata.EpmSourcePathSegment rootSourcePathSegment, Microsoft.Data.OData.ProjectedPropertiesAnnotation projectedProperties)
I: at Microsoft.Data.OData.Atom.ODataAtomWriter.EndEntry(Microsoft.Data.OData.ODataEntry entry)
I: at Microsoft.Data.OData.ODataWriterCore.b__16()
I: at Microsoft.Data.OData.ODataWriterCore.InterceptException(System.Action action)
I: at Microsoft.Data.OData.ODataWriterCore.WriteEndImplementation()
I: at Microsoft.Data.OData.ODataWriterCore.WriteEnd()
I: at System.Data.Services.Client.ODataWriterWrapper.WriteEnd(Microsoft.Data.OData.ODataEntry entry, System.Object entity)
I: at System.Data.Services.Client.Serializer.WriteEntry(System.Data.Services.Client.EntityDescriptor entityDescriptor, IEnumerable`1 relatedLinks, System.Data.Services.Client.ODataRequestMessageWrapper requestMessage)
I: at System.Data.Services.Client.BaseSaveResult.CreateRequestData(System.Data.Services.Client.EntityDescriptor entityDescriptor, System.Data.Services.Client.ODataRequestMessageWrapper requestMessage)
I: at System.Data.Services.Client.BaseSaveResult.CreateChangeData(Int32 index, System.Data.Services.Client.ODataRequestMessageWrapper requestMessage)
I: at System.Data.Services.Client.SaveResult.CreateNonBatchChangeData(Int32 index, System.Data.Services.Client.ODataRequestMessageWrapper requestMessage)
I: at System.Data.Services.Client.SaveResult.BeginCreateNextChange()
I: at System.Data.Services.Client.DataServiceContext.BeginSaveChanges(SaveChangesOptions options, System.AsyncCallback callback, System.Object state)
I: at System.Data.Services.Client.DataServiceContext.BeginSaveChanges(System.AsyncCallback callback, System.Object state)
I: at MyXamarinProject.ViewModel.MyViewModel+c__DisplayClass4.b__1(IAsyncResult result)
I: at System.Data.Services.Client.BaseAsyncResult.HandleCompleted()
I: at System.Data.Services.Client.QueryResult.HandleCompleted(System.Data.Services.Client.PerRequest pereq)
I: at System.Data.Services.Client.QueryResult.AsyncEndRead(IAsyncResult asyncResult)
I: at System.Data.Services.Client.BaseAsyncResult.PostInvokeAsync(IAsyncResult asyncResult, System.AsyncCallback callback)
I: at System.Data.Services.Client.BaseAsyncResult.InvokeAsync(System.Data.Services.Client.AsyncAction asyncAction, System.Byte[] buffer, Int32 offset, Int32 length, System.AsyncCallback callback, System.Object state)
I: at System.Data.Services.Client.QueryResult.ReadResponseStream(System.Data.Services.Client.AsyncStateBag asyncStateBag)
I: at System.Data.Services.Client.QueryResult.AsyncEndRead(IAsyncResult asyncResult)
I: at System.Data.Services.Client.BaseAsyncResult+c__DisplayClass2.b__1(IAsyncResult asyncResult)
I: at System.Net.SimpleAsyncResult+c__AnonStorey0.m__0(System.Net.SimpleAsyncResult result)
I: at System.Net.SimpleAsyncResult.DoCallback_internal()
I: at System.Net.WebAsyncResult.DoCallback()
I: at System.Net.WebConnectionStream.ReadCallbackWrapper(IAsyncResult r)
它永远不会遇到任何问题。
造成这种情况的原因是什么？为什么catch块无法捕获异常？
答案 0 :(得分：0)
它没有抛出异常。它使用Debug.Assert()方法失败了。
巧合的是，Debug.Assert()在MessageBox中显示其输出，您可能会误认为Alert()方法。
错误消息的相关区域：
I: ---- DEBUG ASSERTION FAILED ----
[0:]
---- Assert Short Message ----
I: ---- Assert Short Message ----
[0:]
Expected DateTimeOffset to be a UTC value.
[0:] Expected DateTimeOffset to be a UTC value.
I: Expected DateTimeOffset to be a UTC value.
[0:] at System.Diagnostics.DefaultTraceListener.Fail(System.String message, System.String detailMessage)
I: at System.Diagnostics.DefaultTraceListener.Fail(System.String message, System.String detailMessage)
at System.Diagnostics.TraceListener.Fail(System.String message)
at System.Diagnostics.DefaultTraceListener.Fail(System.String message)
at System.Diagnostics.TraceImpl.Fail(System.String message)
at System.Diagnostics.TraceImpl.Assert(Boolean condition, System.String message)
at System.Diagnostics.Debug.Assert(Boolean condition, System.String message)