It seems to be a bug in webapi.odata:
https://aspnetwebstack.codeplex.com/workitem/1937
But I think the current behavior is to skip the null expanded property rather than throw exception.
Can you try updating the reference to latest version?
Pergunta
When using OData and if one of the properties that are being expanded is null i get this error. Is there anyway to solve this? The output I expect is for the expanded property to be null not throw any exception.
<m:error xmlns:m="http://schemas.microsoft.com/ado/2007/08/dataservices/metadata">
<m:code/>
<m:message xml:lang="en-US">An error has occurred.</m:message>
<m:innererror>
<m:message>
The 'ObjectContent`1' type failed to serialize the response body for content type 'application/json; charset=utf-8'.
</m:message>
<m:type>System.InvalidOperationException</m:type>
<m:stacktrace/>
<m:internalexception>
<m:message>
The EDM instance of type '[Spawtz.OData.Models.Division Nullable=True]' is missing the property 'Id'.
</m:message>
<m:type>System.InvalidOperationException</m:type>
<m:stacktrace>
at System.Web.Http.OData.EntityInstanceContext.GetPropertyValue(String propertyName)
at System.Web.Http.OData.Formatter.Serialization.ODataEntityTypeSerializer.CreateStructuralPro perty(IEdmStructuralProperty structuralProperty, EntityInstanceContext entityInstanceContext)
at System.Web.Http.OData.Formatter.Serialization.ODataEntityTypeSerializer.CreateStructuralPropertyBag(IEnumerable`1 structuralProperties, EntityInstanceContext entityInstanceContext)
at System.Web.Http.OData.Formatter.Serialization.ODataEntityTypeSerializer.CreateEntry(SelectExpandNode selectExpandNode, EntityInstanceContext entityInstanceContext)
at System.Web.Http.OData.Formatter.Serialization.ODataEntityTypeSerializer.WriteEntry(Object graph, ODataWriter writer, ODataSerializerContext writeContext)
at System.Web.Http.OData.Formatter.Serialization.ODataEntityTypeSerializer.WriteExpandedNavigationProperty(KeyValuePair`2 navigationPropertyToExpand, EntityInstanceContext entityInstanceContext, ODataWriter writer)
at System.Web.Http.OData.Formatter.Serialization.ODataEntityTypeSerializer.WriteExpandedNavigationProperties(IDictionary`2 navigationPropertiesToExpand, EntityInstanceContext entityInstanceContext, ODataWriter writer)
at System.Web.Http.OData.Formatter.Serialization.ODataEntityTypeSerializer.WriteEntry(Object graph, ODataWriter writer, ODataSerializerContext writeContext)
at System.Web.Http.OData.Formatter.Serialization.ODataFeedSerializer.WriteFeed(IEnumerable enumerable, IEdmTypeReference feedType, ODataWriter writer, ODataSerializerContext writeContext)
at System.Web.Http.OData.Formatter.Serialization.ODataEntityTypeSerializer.WriteExpandedNavigationProperty(KeyValuePair`2 navigationPropertyToExpand, EntityInstanceContext entityInstanceContext, ODataWriter writer)
at System.Web.Http.OData.Formatter.Serialization.ODataEntityTypeSerializer.WriteExpandedNavigationProperties(IDictionary`2 navigationPropertiesToExpand, EntityInstanceContext entityInstanceContext, ODataWriter writer)
at System.Web.Http.OData.Formatter.Serialization.ODataEntityTypeSerializer.WriteEntry(Object graph, ODataWriter writer, ODataSerializerContext writeContext)
at System.Web.Http.OData.Formatter.Serialization.ODataFeedSerializer.WriteFeed(IEnumerable enumerable, IEdmTypeReference feedType, ODataWriter writer, ODataSerializerContext writeContext)
at System.Web.Http.OData.Formatter.ODataMediaTypeFormatter.WriteToStream(Type type, Object value, Stream writeStream, HttpContent content, HttpContentHeaders contentHeaders)
at System.Web.Http.OData.Formatter.ODataMediaTypeFormatter.WriteToStreamAsync(Type type, Object value, Stream writeStream, HttpContent content, TransportContext transportContext, CancellationToken cancellationToken)
--- End of stack trace from previous location where exception was thrown ---
at System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task task)
at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)
at System.Web.Http.WebHost.HttpControllerHandler.<WriteBufferedResponseContentAsync>d__1b.MoveNext()
</m:stacktrace>
</m:internalexception>
</m:innererror>
Solução
It seems to be a bug in webapi.odata:
https://aspnetwebstack.codeplex.com/workitem/1937
But I think the current behavior is to skip the null expanded property rather than throw exception.
Can you try updating the reference to latest version?