If I try to load a related entity which is null, for instance I have my schema as Carrier has many Phones and I retrieved a Phone and I want to load the Carrier but the Carrier is null (which is ok), then I go to my Container and do "LoadProperty(Phone, "Carrier")" I get an exception because on my Web API OData I have GetCarrier in my PhonesController and when it tries to return the Carrier from this Phone which is null it throws the following error:
```
The 'ObjectContent`1' type failed to serialize the response body for content type 'application/json; odata=minimalmetadata; streaming=true; charset=utf-8'.
```
With an inner exception of:
```
Cannot serialize a null 'entry'.
```
And a stack trace:
```
at System.Web.Http.OData.Formatter.Serialization.ODataEntityTypeSerializer.WriteObject(Object graph, ODataMessageWriter messageWriter, ODataSerializerContext writeContext)
at System.Web.Http.OData.Formatter.ODataMediaTypeFormatter.<>c__DisplayClassa.<WriteToStreamAsync>b__9()
at System.Threading.Tasks.TaskHelpers.RunSynchronously(Action action, CancellationToken token)
--- 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.Tracing.ITraceWriterExtensions.<TraceBeginEndAsyncCore>d__33.MoveNext()
```
Is this by design or should I be handling this differently?
My controller has the following method:
```
public Carrier GetCarrier([FromODataUri] int key)
{
Phone phone = _context.Phones.Find(key);
if (phone == null)
{
throw ODataErrors.EntityNotFound(Request);
}
return phone.Carrier;
}
```
Or should I change my code to the following:
```
public HttpResponseMessage GetCarrier([FromODataUri] int key)
{
Phone phone = _context.Phones.Find(key);
if (phone == null)
{
throw ODataErrors.EntityNotFound(Request);
}
if(phone.Carrier == null)
return Request.CreateResponse(HttpStatusCode.OK);
return Request.CreateResponse(HttpStatusCode.OK, phone.Carrier);
}
```
By doing this I won't get the error anymore when trying to user LoadProperty even if the related entity is null. Is this the correct way of doing this?
Comments: Looks like WCF DS returns 204 (No Content). You could return the same in your action. ``` public HttpResponseMessage GetCarrier([FromODataUri] int key) { Phone phone = _context.Phones.Find(key); if (phone == null) { throw new HttpResponseException(HttpStatusCode.NotFound); } if(phone.Carrier == null) { throw new HttpResponseException(HttpStatusCode.NoContent); } return Request.CreateResponse(HttpStatusCode.OK, phone.Carrier); } ```
```
The 'ObjectContent`1' type failed to serialize the response body for content type 'application/json; odata=minimalmetadata; streaming=true; charset=utf-8'.
```
With an inner exception of:
```
Cannot serialize a null 'entry'.
```
And a stack trace:
```
at System.Web.Http.OData.Formatter.Serialization.ODataEntityTypeSerializer.WriteObject(Object graph, ODataMessageWriter messageWriter, ODataSerializerContext writeContext)
at System.Web.Http.OData.Formatter.ODataMediaTypeFormatter.<>c__DisplayClassa.<WriteToStreamAsync>b__9()
at System.Threading.Tasks.TaskHelpers.RunSynchronously(Action action, CancellationToken token)
--- 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.Tracing.ITraceWriterExtensions.<TraceBeginEndAsyncCore>d__33.MoveNext()
```
Is this by design or should I be handling this differently?
My controller has the following method:
```
public Carrier GetCarrier([FromODataUri] int key)
{
Phone phone = _context.Phones.Find(key);
if (phone == null)
{
throw ODataErrors.EntityNotFound(Request);
}
return phone.Carrier;
}
```
Or should I change my code to the following:
```
public HttpResponseMessage GetCarrier([FromODataUri] int key)
{
Phone phone = _context.Phones.Find(key);
if (phone == null)
{
throw ODataErrors.EntityNotFound(Request);
}
if(phone.Carrier == null)
return Request.CreateResponse(HttpStatusCode.OK);
return Request.CreateResponse(HttpStatusCode.OK, phone.Carrier);
}
```
By doing this I won't get the error anymore when trying to user LoadProperty even if the related entity is null. Is this the correct way of doing this?
Comments: Looks like WCF DS returns 204 (No Content). You could return the same in your action. ``` public HttpResponseMessage GetCarrier([FromODataUri] int key) { Phone phone = _context.Phones.Find(key); if (phone == null) { throw new HttpResponseException(HttpStatusCode.NotFound); } if(phone.Carrier == null) { throw new HttpResponseException(HttpStatusCode.NoContent); } return Request.CreateResponse(HttpStatusCode.OK, phone.Carrier); } ```