OData $select fails with missing property error - api

Question

I'm building an odata service that is used for reading from sql and then rendering the results in json format. I'm not using entityframework though.
When applying the $select filter, if I have less properties than my model (removing a nullable one), I'm getting the following error. If I have the exact same amount of properties, everything works fine.
{
"error": {
"code": "",
"message": "An error has occurred.",
"innererror": {
"message": "The 'ObjectContent`1' type failed to serialize the response body for content type 'application/json; odata.metadata=minimal'.",
"type": "System.InvalidOperationException",
"stacktrace": "",
"internalexception": {
"message": "The EDM instance of type '[PrototypeOData.Models.DefaultRule Nullable=True]' is missing the property 'DateLastModified'.",
"type": "System.InvalidOperationException",
"stacktrace": " at System.Web.OData.EntityInstanceContext.GetPropertyValue(String propertyName)\r\n at System.Web.OData.Formatter.Serialization.ODataEntityTypeSerializer.CreateStructuralProperty(IEdmStructuralProperty structuralProperty, EntityInstanceContext entityInstanceContext)\r\n at System.Web.OData.Formatter.Serialization.ODataEntityTypeSerializer.CreateStructuralPropertyBag(IEnumerable`1 structuralProperties, EntityInstanceContext entityInstanceContext)\r\n at System.Web.OData.Formatter.Serialization.ODataEntityTypeSerializer.CreateEntry(SelectExpandNode selectExpandNode, EntityInstanceContext entityInstanceContext)\r\n at System.Web.OData.Formatter.Serialization.ODataEntityTypeSerializer.WriteEntry(Object graph, ODataWriter writer, ODataSerializerContext writeContext)\r\n at System.Web.OData.Formatter.Serialization.ODataEntityTypeSerializer.WriteObjectInline(Object graph, IEdmTypeReference expectedType, ODataWriter writer, ODataSerializerContext writeContext)\r\n at System.Web.OData.Formatter.Serialization.ODataFeedSerializer.WriteFeed(IEnumerable enumerable, IEdmTypeReference feedType, ODataWriter writer, ODataSerializerContext writeContext)\r\n at System.Web.OData.Formatter.Serialization.ODataFeedSerializer.WriteObjectInline(Object graph, IEdmTypeReference expectedType, ODataWriter writer, ODataSerializerContext writeContext)\r\n at System.Web.OData.Formatter.Serialization.ODataFeedSerializer.WriteObject(Object graph, Type type, ODataMessageWriter messageWriter, ODataSerializerContext writeContext)\r\n at System.Web.OData.Formatter.ODataMediaTypeFormatter.WriteToStream(Type type, Object value, Stream writeStream, HttpContent content, HttpContentHeaders contentHeaders)\r\n at System.Web.OData.Formatter.ODataMediaTypeFormatter.WriteToStreamAsync(Type type, Object value, Stream writeStream, HttpContent content, TransportContext transportContext, CancellationToken cancellationToken)\r\n--- End of stack trace from previous location where exception was thrown ---\r\n at System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task task)\r\n at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)\r\n at System.Runtime.CompilerServices.TaskAwaiter.GetResult()\r\n at System.Web.Http.WebHost.HttpControllerHandler.<WriteBufferedResponseContentAsync>d__14.MoveNext()"
}
}
}
}
My model looks like this:
public class DefaultRule
{
public string Id { get; set; }
public int? RequestedCount { get; set; }
public DateTime? DateLastModified { get; set; }
}
In my controller the calls are as follows:
public IHttpActionResult Get(ODataQueryOptions<DefaultRule> options)
{
.............
var res = options.SelectExpand.ApplyTo(result, new ODataQuerySettings() { PageSize = 100}).AsQueryable();
//return result;
return Ok(res, res.GetType());
}
private IHttpActionResult Ok(object content, Type type)
{
Type resultType = typeof(OkNegotiatedContentResult<>).MakeGenericType(type);
return Activator.CreateInstance(resultType, content, this) as IHttpActionResult;
}
Is there any way I can mark specific properties as optional?
Any thoughts are appreciated.

Answer 1

This is because your the result of $select is not your original model. Then error occurs in Serialization. Try add the pagesize in attribute like:
[EnableQuery(PageSize=100)]
or create your own attribute
public class MyEnableQueryAttribute : EnableQueryAttribute
{
public override IQueryable ApplyQuery(IQueryable queryable, ODataQueryOptions queryOptions)
{
return options.SelectExpand.ApplyTo(result, new ODataQuerySettings() { PageSize = 100}).AsQueryable().
}
}
[MyEnableQueryAttribute]
public IHttpActionResult Get()
{
....
return result;
}