how to display data from self nested table using web api in

i have a table which is licked to itself . and also one another table. followings are my code lines.when i run this api in browser i got error of serialization. Please help me. I am new learner of MVC and Web Api

Model.cs

namespace firstMvc1.Models

{

using System;

using System.Collections.Generic;

using System.ComponentModel.DataAnnotations;

using System.ComponentModel.DataAnnotations.Schema;

using System.Data.Entity.Spatial;

[Table("CATEGORIES")]

public partial class CATEGORy

{

[System.Diagnostics.CodeAnalysis.SuppressMessage("Microsoft.Usage", "CA2214:DoNotCallOverridableMethodsInConstructors")]

public CATEGORy()

{

ARTICELS = new HashSet();

CATEGORIES1 = new HashSet();

}

public int ID { get; set; }

[StringLength(200)]

public string CATEGORY_NAME { get; set; }

public int? PARENT_ID { get; set; }

public bool? STATUS { get; set; }

[System.Diagnostics.CodeAnalysis.SuppressMessage("Microsoft.Usage", "CA2227:CollectionPropertiesShouldBeReadOnly")]

public virtual ICollection ARTICELS { get; set; }

[System.Diagnostics.CodeAnalysis.SuppressMessage("Microsoft.Usage", "CA2227:CollectionPropertiesShouldBeReadOnly")]

public virtual ICollection CATEGORIES1 { get; set; }

public virtual CATEGORy CATEGORy1 { get; set; }

}

dataModel.cs

namespace firstMvc1.Models

{

using System;

using System.Data.Entity;

using System.ComponentModel.DataAnnotations.Schema;

using System.Linq;

public partial class ModelData : DbContext

{

public ModelData()

: base("name=ModelData")

{

}

public virtual DbSet ARTICELS { get; set; }

public virtual DbSet CATEGORIES { get; set; }

protected override void OnModelCreating(DbModelBuilder modelBuilder)

{

modelBuilder.Entity()

.Property(e => e.TITLE)

.IsUnicode(false);

modelBuilder.Entity()

.Property(e => e.CONTENT)

.IsUnicode(false);

modelBuilder.Entity()

.Property(e => e.ArticleImage);

modelBuilder.Entity()

.Property(e => e.CATEGORY_NAME)

.IsUnicode(false);

modelBuilder.Entity()

.HasMany(e => e.CATEGORIES1)

.WithOptional(e => e.CATEGORy1)

.HasForeignKey(e => e.PARENT_ID);

}

ApiController.cs

using System;

using System.Collections.Generic;

using System.Data;

using System.Data.Entity;

using System.Data.Entity.Infrastructure;

using System.Linq;

using System.Net;

using System.Net.Http;

using System.Web.Http;

using System.Web.Http.Description;

using firstMvc1.Models;

namespace firstMvc1.Controllers

{

public class CATEGORyApiController : ApiController

{

private ModelData db = new ModelData();

// GET: api/CATEGORyApi

public IQueryable GetCATEGORIES()

{

return db.CATEGORIES;

//var cat = db.CATEGORIES.Include("ARTICELS").Select(a=>new {a.CATEGORY_NAME,a.ID });

//return cat;

}

// GET: api/CATEGORyApi/5

[ResponseType(typeof(CATEGORy))]

public IHttpActionResult GetCATEGORy(int id)

{

CATEGORy cATEGORy = db.CATEGORIES.Find(id);

if (cATEGORy == null)

{

return NotFound();

}

return Ok(cATEGORy);

}

// PUT: api/CATEGORyApi/5

[ResponseType(typeof(void))]

public IHttpActionResult PutCATEGORy(int id, CATEGORy cATEGORy)

{

if (!ModelState.IsValid)

{

return BadRequest(ModelState);

}

if (id != cATEGORy.ID)

{

return BadRequest();

}

db.Entry(cATEGORy).State = EntityState.Modified;

try

{

db.SaveChanges();

}

catch (DbUpdateConcurrencyException)

{

if (!CATEGORyExists(id))

{

return NotFound();

}

else

{

throw;

}

return StatusCode(HttpStatusCode.NoContent);

}

// POST: api/CATEGORyApi

[ResponseType(typeof(CATEGORy))]

public IHttpActionResult PostCATEGORy(CATEGORy cATEGORy)

{

if (!ModelState.IsValid)

{

return BadRequest(ModelState);

}

db.CATEGORIES.Add(cATEGORy);

db.SaveChanges();

return CreatedAtRoute("DefaultApi", new { id = cATEGORy.ID }, cATEGORy);

}

// DELETE: api/CATEGORyApi/5

[ResponseType(typeof(CATEGORy))]

public IHttpActionResult DeleteCATEGORy(int id)

{

CATEGORy cATEGORy = db.CATEGORIES.Find(id);

if (cATEGORy == null)

{

return NotFound();

}

db.CATEGORIES.Remove(cATEGORy);

db.SaveChanges();

return Ok(cATEGORy);

}

protected override void Dispose(bool disposing)

{

if (disposing)

{

db.Dispose();

}

base.Dispose(disposing);

}

private bool CATEGORyExists(int id)

{

return db.CATEGORIES.Count(e => e.ID == id) > 0;

}