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...

Answer 2

I had a similar issue and likewise i was not able to resolve the underlying issue. I figure the server is using a dll different from localhost for the conversion to json via json.encode.

I did post the question and my resolution here A circular reference was detected while serializing with Json.Encode

I resolved with mvchelper.

Answer 3

You could use this code and do not use select Extention function to filter your column.

var list = JsonConvert.SerializeObject(Yourmodel,
    Formatting.None,
    new JsonSerializerSettings() {
        ReferenceLoopHandling = Newtonsoft.Json.ReferenceLoopHandling.Ignore
});
return list;

Answer 4

I'm Using the fix, Because Using Knockout in MVC5 views.

On action

return Json(ModelHelper.GetJsonModel<Core_User>(viewModel));

function

   public static TEntity GetJsonModel<TEntity>(TEntity Entity) where TEntity : class
    {
        TEntity Entity_ = Activator.CreateInstance(typeof(TEntity)) as TEntity;
        foreach (var item in Entity.GetType().GetProperties())
        {
            if (item.PropertyType.ToString().IndexOf("Generic.ICollection") == -1 && item.PropertyType.ToString().IndexOf("SaymenCore.DAL.") == -1)
                item.SetValue(Entity_, Entity.GetPropValue(item.Name));
        }
        return Entity_;  
    }