How to set custom JsonSerializerSettings for Json.NET in ASP.NET Web API?

I understand that ASP.NET Web API natively uses Json.NET for (de)serializing objects, but is there a way to specify a JsonSerializerSettings object that you want for it to use?

For example, what if I wanted to include type information into the serialized JSON string? Normally I'd inject settings into the .Serialize() call, but Web API does that silently. I can't find a way to inject settings manually.

Solution 1:

You can customize the JsonSerializerSettings by using the Formatters.JsonFormatter.SerializerSettings property in the HttpConfiguration object.

For example, you could do that in the Application_Start() method:

protected void Application_Start()
{
    HttpConfiguration config = GlobalConfiguration.Configuration;
    config.Formatters.JsonFormatter.SerializerSettings.Formatting =
        Newtonsoft.Json.Formatting.Indented;
}

Solution 2:

You can specify JsonSerializerSettings for each JsonConvert, and you can set a global default.

Single JsonConvert with an overload:

// Option #1.
JsonSerializerSettings config = new JsonSerializerSettings { ReferenceLoopHandling = Newtonsoft.Json.ReferenceLoopHandling.Ignore };
this.json = JsonConvert.SerializeObject(YourObject, Formatting.Indented, config);

// Option #2 (inline).
JsonConvert.SerializeObject(YourObject, Formatting.Indented,
    new JsonSerializerSettings() {
        ReferenceLoopHandling = Newtonsoft.Json.ReferenceLoopHandling.Ignore
    }
);

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

Solution 3:

Answer is adding this 2 lines of code to Global.asax.cs Application_Start method

var json = GlobalConfiguration.Configuration.Formatters.JsonFormatter;
json.SerializerSettings.PreserveReferencesHandling = 
    Newtonsoft.Json.PreserveReferencesHandling.All;

Reference: Handling Circular Object References