JSON serialization fails with parent/child related entities in EF 6.1 - asp.net-web-api

Question

I see that other folks have add issue with this error when trying to serialize an entity that has a navigation property to a collection of other entities such as in a parent child relationship.
The 'ObjectContent`1' type failed to serialize the response body for content type 'application/json; charset=utf-8'.",
I have tried added these options to the Register method inside the WebApiConfig.cs file but I still get the same error.
var json = config.Formatters.JsonFormatter;
json.SerializerSettings.PreserveReferencesHandling = Newtonsoft.Json.PreserveReferencesHandling.Objects;
config.Formatters.Remove(config.Formatters.XmlFormatter);
json.SerializerSettings.ReferenceLoopHandling = Newtonsoft.Json.ReferenceLoopHandling.Ignore;

Answer 1

Best way I found to do this is to add
[JsonIgnore]
attributes in the entity for the references that you don't need to serialize (I use buddy classes to annotate the entities). This is an example:
[MetadataType(typeof(MenuItemValidation))]
public partial class MenuItem
{
public class MenuItemValidation
{
public int Id { get; set; }
public int Menu_Id { get; set; }
[Required]
public string Title { get; set; }
[Required]
public string Url { get; set; }
[Required]
public int SortOrder { get; set; }
public bool HasIcon { get; set; }
public string IconClass { get; set; }
public bool IsActive { get; set; }
public bool IsDeleted { get; set; }
[JsonIgnore]
public System.DateTime CreatedOn { get; set; }
[JsonIgnore]
public System.Guid CreatedBy_Id { get; set; }
[JsonIgnore]
public System.DateTime UpdatedOn { get; set; }
[JsonIgnore]
public System.Guid UpdatedBy_Id { get; set; }
public bool IsMegaMenu { get; set; }
public virtual ICollection<MenuItem> Children { get; set; }
[JsonIgnore]
public virtual MenuItem Parent { get; set; }
[JsonIgnore]
public virtual Menu Menu { get; set; }
[JsonIgnore]
public virtual User CreatedBy { get; set; }
[JsonIgnore]
public virtual User UpdatedBy { get; set; }
[JsonIgnore]
public virtual ICollection<MenuItemsLocalization> MenuItemsLocalizations { get; set; }
}
}
I also added:
var json = config.Formatters.JsonFormatter;
json.SerializerSettings.Formatting = Newtonsoft.Json.Formatting.Indented;
json.SerializerSettings.PreserveReferencesHandling = Newtonsoft.Json.PreserveReferencesHandling.Objects;
config.Formatters.Remove(config.Formatters.XmlFormatter);
inside App_Start/WebApiConfig.cs