Entity Framework Circular References

One of the first issues I encountered returning serialized, nested (“deep”) entities using EF5 with the (MVC4) ASP.NET Web Api was the “Self Referencing loop” exception*

For any property you don’t want exposed, make the Getter: Internal & Setter: Public.

Doing this on the navigation properties that reference the parent that reference it will prevent the “circular reference” error:

Doing this on standard (field) properties will prevent those fields from being serialized & exposed (for example, in the ASP.NET Web Api).

1. This means there is no need to add Newtonsoft.Json.PreserveReferencesHandling settings to your Global.asax Application_Start which results in REALLY ANNOYING $ref & $id properties being added to your serialized results).

2. This also means there is no need to create partial classes with MetadataType attributes for every class that define [JsonIgnore] or [XmlIgnore] attributes on specific properties to prevent this

   Note: This is still a GREAT way to add things like data validation attributes to properties generated using db-first EF. They’re just not necessary to prevent the circular ref exception.

I hope this helps save someone some of the time I spent this week attempting to work around it.

Big thanks to @DavidBitton for the ongoing Twitter dialog that led to this easier-to-implement-than-other-findings solution.

---

*{“Message”:”An error has occurred.”,”ExceptionMessage”:”The ‘ObjectContent`1′ type failed to serialize the response body for content type ‘application/json; charset=utf-8′.”,”ExceptionType”:”System.InvalidOperationException”,”StackTrace”:null,”InnerException”:{“Message”:”An error has occurred.”,”ExceptionMessage”:”Self referencing loop detected for property ‘Customer’ with type ‘Namespace.Customer. Path ‘CustomerOrders[0]‘.”,”ExceptionType”:”Newtonsoft.Json.JsonSerializationException”,”StackTrace”:”   at Newtonsoft.Json.Serialization.JsonSerializerInternalWriter.CheckForCircularReference(JsonWriter writer, Object value, JsonProperty property, JsonContract contract, JsonContainerContract containerContract, JsonProperty containerProperty)\r\n   at Newtonsoft.Json.Serialization.JsonSerializerInternalWriter.CalculatePropertyValues(JsonWriter writer, Object value, JsonContainerContract contract, JsonProperty member, JsonProperty property, JsonContract& memberContract, Object& memberValue)\r\n   at Newtonsoft.Json.Serialization.JsonSerializerInternalWriter.SerializeObject(JsonWriter writer, Object value, JsonObjectContract contract, JsonProperty member, JsonContainerContract collectionContract, JsonProperty containerProperty)\r\n   at Newtonsoft.Json.Serialization.JsonSerializerInternalWriter.SerializeValue(JsonWriter writer, Object value, JsonContract valueContract, JsonProperty member, JsonContainerContract containerContract, JsonProperty containerProperty)\r\n   at Newtonsoft.Json.Serialization.JsonSerializerInternalWriter.SerializeList(JsonWriter writer, IWrappedCollection values, JsonArrayContract contract, JsonProperty member, JsonContainerContract collectionContract, JsonProperty containerProperty)\r\n   at Newtonsoft.Json.Serialization.JsonSerializerInternalWriter.SerializeValue(JsonWriter writer, Object value, JsonContract valueContract, JsonProperty member, JsonContainerContract containerContract, JsonProperty containerProperty)\r\n   at Newtonsoft.Json.Serialization.JsonSerializerInternalWriter.SerializeObject(JsonWriter writer, Object value, JsonObjectContract contract, JsonProperty member, JsonContainerContract collectionContract, JsonProperty containerProperty)\r\n   at Newtonsoft.Json.Serialization.JsonSerializerInternalWriter.SerializeValue(JsonWriter writer, Object value, JsonContract valueContract, JsonProperty member, JsonContainerContract containerContract, JsonProperty containerProperty)\r\n   at Newtonsoft.Json.Serialization.JsonSerializerInternalWriter.Serialize(JsonWriter jsonWriter, Object value)\r\n   at Newtonsoft.Json.JsonSerializer.SerializeInternal(JsonWriter jsonWriter, Object value)\r\n   at System.Net.Http.Formatting.JsonMediaTypeFormatter.<>c__DisplayClassd.<WriteToStreamAsync>b__c()\r\n   at System.Threading.Tasks.TaskHelpers.RunSynchronously(Action action, CancellationToken token)”}}