c# - Json A circular reference was detected while serializing an object of type

Question

Give the classes:

public class Parent
{
    public int id {get; set;}
    public int name {get; set;}

    public virtual ICollection<Child> children {get; set;}
}

[Table("Child")]
public partial class Child
{
    [Key]
    public int id {get; set;}
    public string name { get; set; }

    [NotMapped]
    public string nickName { get; set; }
}

And the controller code:

List<Parent> parents = parentRepository.Get();
return Json(parents); 

It works on LOCALHOST, but it does not work on live server:

ERROR : Json A circular reference was detected while serializing an object of type

I did a search and found the [ScriptIgnore] attribute, so I changed the model to

using System.Web.Script.Serialization;

public class Parent
{
    public int id {get; set;}
    public int name {get; set;}

    [ScriptIgnore]
    public virtual ICollection<Child> children {get; set;}
}

But the same error occur on live server (win2008).

How can I avoid that error and serialize the parent data successfully?

Answer 1

Try the following code:

return Json(
    parents.Select(x => new {
        id = x.id,
        name = x.name,
        children = x.children.Select(y => new {
            // Assigment of child fields
        })
    })); 

...or if you only need the parent properties:

return Json(
    parents.Select(x => new {
        id = x.id,
        name = x.name
    })); 

It is not really the solution for the problem, but it is a common workaround when serializing DTOs...