Question

I have WCF with DataContract defined and a few other DataContract that extend it. So it looks something like this in it’s primitive form:

    [DataContract(Name = "FacilityPerson"]
    [KnownType(typeof(Student))]
    [KnownType(typeof(Teacher))]
    public class Person
    {
        [DataMember(IsRequired=true)]
        public string FirstName { get; set; }
        [DataMember]
        public string LastName { get; set; }
        [DataMember]
        public DateTime? DOB { get; set; }   

    }

    [DataContract]
    public class Student
    {
        [DataMember(IsRequired=true)]
        public int StudentID { get; set; }

    }

[DataContract]
public class Teacher
{
    [DataMember(IsRequired=true)]
    public int StaffID { get; set; }

}

I have a ServieContract that has only one operation and looks like this:

[OperationContract(Name = "ReportNewPerson")]
void ReportNewTeacherOrStudent(Person person);

My problem is when I am implementing it, I can’t access children properties of a parent object.

public class UniversityService : IUniversityServiceContract  
{

        void ReportNewTeacherOrStudent(Person person)
        {
             if(person.GetType().FullName == "Student")
             {
                     //here I have a parent object so I cannot getStudentId which is a child property           
                     Console.Writeline(person.StudentId);

             }

        }
}

What should I do here?

Answer 1

Don’t compare the type from the name; instead, use a cast or the as operator to do that:

public class UniversityService : IUniversityServiceContract  
{
    public void ReportNewTeacherOrStudent(Person person)
    {
        Student student = person as Student;
        if (student != null)
        {
            Console.Writeline(student.StudentId);
        }
    }
}