ASP.Net WebApi is not serializing bool if set to true

Question

I have the following model:

public class DocumentViewModel
{
    public long Id { get; set; }
    public long? ParentFolderId { get; set; }
    public bool IsFolder { get; set; }
    public bool IsImage { get; set; }
}

and the following API Controller:

public HttpResponseMessage GetChildren(long jobId, long folderId)
{            
    using (var model = DatabaseHelper.GetModel())
    {
        var accessLevel = MembershipHelper.GetLoggedInAccessLevel(model);
        List<DocumentViewModel> documents = DocumentHelper.GetDocumentsForMobile(model, jobId, folderId, accessLevel).ToList();

        return this.Request.CreateResponse(
            HttpStatusCode.OK,
            new { data = documents });
    }
}

The problem is that IsFolder and IsImage are missing from the json when I review this in Fiddler when they are set to false. They show up fine when they are set to true.

I suspect this is because .Net thinks true is the default value, and excludes fields where the value is the same as the default.

How do I tell .Net to ALWAYS include this value, regardless?

Answer 1

In the Register method of the WebApiConfig class (located in the App_Start folder) try adding this line:

config.Formatters.JsonFormatter.SerializerSettings.DefaultValueHandling =
                                   Newtonsoft.Json.DefaultValueHandling.Include;

This should force Web Api to include default values if it isn't already.

EDIT

If you're using an older version of Web API that does not have a WebApiConfig, you can also do this in the Application_Start method in Global.asax.cs:

var config = GlobalConfiguration.Configuration;
var jsonSettings = config.Formatters.JsonFormatter.SerializerSettings;
jsonSettings.DefaultValueHandling = Newtonsoft.Json.DefaultValueHandling.Include;