JSON.Net Self referencing loop detected

Question

I just had the same problem with Parent/Child collections and found that post which has solved my case. I Only wanted to show the List of parent collection items and didn't need any of the child data, therefore i used the following and it worked fine:

JsonConvert.SerializeObject(ResultGroups, Formatting.None,
                        new JsonSerializerSettings()
                        { 
                            ReferenceLoopHandling = ReferenceLoopHandling.Ignore
                        });

JSON.NET Error Self referencing loop detected for type

it also referes to the Json.NET codeplex page at:

http://json.codeplex.com/discussions/272371

Documentation: ReferenceLoopHandling setting

The fix is to ignore loop references and not to serialize them. This behaviour is specified in JsonSerializerSettings.

Single JsonConvert with an overload:

JsonConvert.SerializeObject((from a in db.Events where a.Active select a).ToList(), Formatting.Indented,
    new JsonSerializerSettings() {
        ReferenceLoopHandling = Newtonsoft.Json.ReferenceLoopHandling.Ignore
    }
);

If you'd like to make this the default behaviour, add a Global Setting with code in Application_Start() in Global.asax.cs:

JsonConvert.DefaultSettings = () => new JsonSerializerSettings {
     Formatting = Newtonsoft.Json.Formatting.Indented,
     ReferenceLoopHandling = Newtonsoft.Json.ReferenceLoopHandling.Ignore
};

Reference: https://github.com/JamesNK/Newtonsoft.Json/issues/78

If using ASP.NET Core MVC, add this to the ConfigureServices method of your startup.cs file:

services.AddMvc()
    .AddJsonOptions(
        options => options.SerializerSettings.ReferenceLoopHandling =            
        Newtonsoft.Json.ReferenceLoopHandling.Ignore
    );

This may help you.

public MyContext() : base("name=MyContext") 
{ 
    Database.SetInitializer(new MyContextDataInitializer()); 
    this.Configuration.LazyLoadingEnabled = false; 
    this.Configuration.ProxyCreationEnabled = false; 
} 

http://code.msdn.microsoft.com/Loop-Reference-handling-in-caaffaf7

You must set Preserving Object References:

var jsonSerializerSettings = new JsonSerializerSettings
{
    PreserveReferencesHandling = PreserveReferencesHandling.Objects
};

Then call your query var q = (from a in db.Events where a.Active select a).ToList(); like

string jsonStr = Newtonsoft.Json.JsonConvert.SerializeObject(q, jsonSerializerSettings);

See: https://www.newtonsoft.com/json/help/html/PreserveObjectReferences.htm

I am using Dot.Net Core 3.1 and did an search for

"Newtonsoft.Json.JsonSerializationException: Self referencing loop detected for property "

I am adding this to this question, as it will be an easy reference. You should use the following in the Startup.cs file:

 services.AddControllers()
                .AddNewtonsoftJson(options =>
                {
                    // Use the default property (Pascal) casing
                    options.SerializerSettings.ContractResolver = new CamelCasePropertyNamesContractResolver();
                    options.SerializerSettings.ReferenceLoopHandling = ReferenceLoopHandling.Ignore;
                });

Add "[JsonIgnore]" to your model class

{
  public Customer()
  {
    Orders = new Collection<Order>();
  }

public int Id { get; set; }
public string Name { get; set; }
public string Surname { get; set; }

[JsonIgnore]
public ICollection<Order> Orders { get; set; }
}