Failed to serialize the response in Web API with Json

Question

I am working with ASP.NET MVC 5 Web Api. I want consult all my users.

I wrote api/users and I receive this:

"The 'ObjectContent`1' type failed to serialize the response body for content type 'application/json; charset=utf-8'"

In WebApiConfig, already I added these lines:

HttpConfiguration config = new HttpConfiguration();
config.Formatters.XmlFormatter.SupportedMediaTypes.Remove(appXmlType);
config.Formatters.JsonFormatter.SerializerSettings.ReferenceLoopHandling = Newtonsoft.Json.ReferenceLoopHandling.Ignore; 

But it still doesn't work.

My function for return data is this:

public IEnumerable<User> GetAll()
{
    using (Database db = new Database())
    {
        return db.Users.ToList();
    }
}

Answer 1

If you are working with EF, besides adding the code below on Global.asax

GlobalConfiguration.Configuration.Formatters.JsonFormatter.SerializerSettings
    .ReferenceLoopHandling = Newtonsoft.Json.ReferenceLoopHandling.Ignore;
GlobalConfiguration.Configuration.Formatters
    .Remove(GlobalConfiguration.Configuration.Formatters.XmlFormatter);          

Dont`t forget to import

using System.Data.Entity;

Then you can return your own EF Models

Simple as that!