Web API Conditional Serialization of properties using attributes

Question

How to include/exclude properties from a WEB API response based on a user's role using attributes? For example:

public class Employee 
{ 
    public string FullName { get; set;}

    [DataMember(Role="SystemAdmin")] // included only for SystemAdmins
    public string SSN { get; set; }
}

Answer 1

You can use conditional serialization depending on what serializer(s) you are using in web api.

If you are just returning JSON from Web API its simple - I use only the JSON serializer and this solution works for me. By default Web API uses JSON.Net for JSON serialization. You can add a ShouldSerialize method that returns a bool. In the should serialize you can test if the user IsInRole

public class Employee
{
   public string Name { get; set; }
   public string Manager { get; set; }

   public bool ShouldSerializeManager()
   {
    // don't serialize the Manager property for anyone other than Bob..
    return (Name == "Bob");
   }

}

More details

The [JsonIgnore] attribute is all or nothing when using the JSON.Net Web API serialization.

Other serializers require different approaches...

The XmlSerializer also supports this but you have to enable it

config.Formatters.XmlFormatter.UseXmlSerializer = true;  

The datacontract serializer is the default.

If using this you would have to add logic into the properties and omit them if null.. This can be a problem if you use the class elsewhere. The [IgnoreDataMember] attribute is all or nothing.

[DataContract]
public class Person
{
  private string firstName;
  [DataMember(IsRequired = false, EmitDefaultValue = false)]
  public string FirstName
  {
    get
    {
        //Put here any condition for serializing
        return string.IsNullOrWhiteSpace(firstName) ? null : firstName;
    }
    set
    {
        firstName = value;
    }
  }
}