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POSerializing EF4.1 Entities using JSON.Net
 

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    <p>I am building an application using MVC3, Razor view engine, Repository Pattern with Unit of Work and using EF4.1 Code First to define my data model.</p> <p>Here is a bit of background (gloss over it if you want).</p> <p>The application itself is just an Intranet 'Menu'.</p> <p>The 2 main entities are MenuItem and Department of which:</p> <ul> <li>MenuItem can have many Departments</li> <li>Departments can have many MenuItems</li> <li>MenuItem may have a MenuItem as a parent</li> </ul> <p>This is how I have defined my Entities</p> <pre><code>public class MenuItem { public int MenuItemId { get; set; } public string Name { get; set; } public string Url { get; set; } public virtual ICollection&lt;Department&gt; Departments { get; set; } public int? ParentId { get; set; } public virtual MenuItem ParentMenuItem { get; set; } } public class Department { public int DepartmentId { get; set; } public string Name { get; set; } public virtual ICollection&lt;MenuItem&gt; MenuItems { get; set; } } </code></pre> <p>I am using the FluentAPI to define the Self Reference Many-to-Many for the MenuItem.</p> <p>The issue I am having is passing a MenuItem to the view via JSON. The central issues are that I have a circular reference between my entities that the built in JSON parser can't deal with and I have lazy loading and proxy generation still enabled.</p> <p>I am using JSON.net library from Nuget as my JSON Serializer as this seems to be a nice way round the circular reference issue. I now am unsure how to 'fix' the proxy generation issue. Currently the serializer throws <code>The RelationshipManager object could not be serialized. This type of object cannot be serialized when the RelationshipManager belongs to an entity object that does not implement IEntityWithRelationships.</code></p> <p>Can anyone help me with this? If I turn off proxy generation, I am going to have a hell of a time loading all of the MenuItem children so I am keen leave this on. I have read a fair amount and there seems to be a variety of different answers including projecting the entities into another object and serialize that, etc, etc. Ideally there would be some way of configuring JSON.net to ignore the RelationshipManager object?</p> <p><strong>Update</strong></p> <p>Here is what I have used as a Custom ContractResolver for JSON.Net serializer. This seems to have sorted out my issue.</p> <pre><code>public class ContractResolver : DefaultContractResolver { private static readonly IEnumerable&lt;Type&gt; Types = GetEntityTypes(); private static IEnumerable&lt;Type&gt; GetEntityTypes() { var assembly = Assembly.GetAssembly(typeof (IEntity)); var types = assembly.GetTypes().Where(t =&gt; String.Equals(t.Namespace, "Namespace", StringComparison.Ordinal)); return types; } protected override List&lt;MemberInfo&gt; GetSerializableMembers(Type objectType) { if (!AllowType(objectType)) return new List&lt;MemberInfo&gt;(); var members = base.GetSerializableMembers(objectType); members.RemoveAll(memberInfo =&gt; (IsMemberEntityWrapper(memberInfo))); return members; } private static bool AllowType(Type objectType) { return Types.Contains(objectType) || Types.Contains(objectType.BaseType); } private static bool IsMemberEntityWrapper(MemberInfo memberInfo) { return memberInfo.Name == "_entityWrapper"; } } </code></pre> <p><code>IEntity</code> is an interface all my Code First entity objects implement.</p>
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