Question

So I have an windows form application (client) which displays which groups belong to a student.

On the service side this is done like so:

    List<Student> students = new List<Student>();
    List<Group> Groups = new List<Group>();
    public List<Group> GetStudentCollectionByGroup(string anything)
    {

        List<Group> groups = (from g in Groups
                              where
                                  (from t in g.Groupsz where
                                          string.Equals(t.StudentID, anything, StringComparison.CurrentCultureIgnoreCase)
                                       || string.Equals(t.FirstName, anything, StringComparison.CurrentCultureIgnoreCase)
                                       || string.Equals(t.LastName, anything, StringComparison.CurrentCultureIgnoreCase)
                                   select t).Count() > 0
                              select g).ToList();
        return groups;
    }

To add a student to a group I have used this method:

    public void AddStudentToGroup(string group, string studentID, string firstName, string lastName)
    {
        var result = Groups.Where(n => String.Equals(n.GroupName, group)).FirstOrDefault();
        if (result != null)
        {
            result.Groupsz.Add(new Student() { StudentID = studentID });
            result.Groupsz.Add(new Student() { FirstName = firstName });
            result.Groupsz.Add(new Student() { LastName = lastName });
        }
    }  

And my GET method looks like this:

    [OperationContract]
    [WebInvoke(Method = "GET", BodyStyle = WebMessageBodyStyle.Bare, RequestFormat = WebMessageFormat.Xml, ResponseFormat = WebMessageFormat.Xml, UriTemplate = "/GetStudentCollectionByGroup/{anything}")]
    List<Group> GetStudentCollectionByGroup(string anything);

The data contracts look like this:

public class Student
{
    public Student()
    {
        StudentGroup = new List<Group>();
    }
    [DataMember(Name = "StudentID")]
    public string StudentID { get; set; }
    [DataMember(Name = "FirstName")]
    public string FirstName { get; set; }
    [DataMember(Name = "LastName")]
    public string LastName { get; set; }
    public List<Group> StudentGroup { get; set; }
}
[DataContract(Name = "Group")]
public class Group
{
    public Group() 
    {
        Groupsz = new List<Student>();
    }
    public string GroupName { get; set; }
    public List<Student> Groupsz { get; set; }
}

Now I have no problem getting the group from my client side when I type in the specific student. But when I type into a different textbox to get the students based on Group nothing is returned? For instance if I type group “A” it should return all the students who belong to that group. Just like how I return a collection of groups who belong to student “B”

Answer 1

I think I found the problem, not sure why but adding the student to the group and group to the student seems to work. However I could be duplicating records.

  public void AddStudentToGroup(string group, string studentID, string firstName, string lastName)
    {
        var result = Groups.Where(n => String.Equals(n.GroupName, group)).FirstOrDefault();
        var result1 = students.Where(n => String.Equals(n.StudentID, studentID)).FirstOrDefault();
        if (result != null)
        {
            result.Groupsz.Add(new Student() { StudentID = studentID, FirstName = firstName, LastName = lastName });
        }
        if (result1 != null)
        {
            result1.StudentGroup.Add(new Group() { GroupName = group });
        }

    }