My previous blog is about using DTO in UI/Presenter layers. Just studying Nhibernate source code now, I find a very interesting approach to populate DTO object directly from Nhibernate with Criteria and Projections.
Here is the code:
1: IList resultWithAliasedBean = s.CreateCriteria(typeof(Enrolment))
2: .CreateAlias("Student", "st")
3: .CreateAlias("Course", "co")
4: .SetProjection(Projections.ProjectionList()
5: .Add(Projections.Property("st.Name"), "studentName")
6: .Add(Projections.Property("co.Description"), "courseDescription")
7: )
8: .AddOrder(Order.Desc("studentName"))
9: .SetResultTransformer(NHibernate.Transform.Transformers 10. .AliasToBean(typeof(StudentDTO)))
11: .List();
The Element and StudentDTO is simple enough.
1: [Serializable]
2: public class Enrolment
3:
4: private Student student;
5: public virtual Student Student
6: {
7: get { return student; }
8: set { student = value; }
9: }
10:
11: private Course course;
12: public virtual Course Course
13: {
14: get { return course; }
15: set { course = value; }
16: }
17:
18: private long studentNumber;
19: public virtual long StudentNumber
20: {
21: get { return studentNumber; }
22: set { studentNumber = value; }
23: }
24:
25: private string courseCode = string.Empty;
26: public virtual string CourseCode
27: {
28: get { return courseCode; }
29: set { courseCode = value; }
30: }
31:
32: private short year;
33: public virtual short Year
34: {
35: get { return year; }
36: set { year = value; }
37: }
38:
39: private short semester;
40: public virtual short Semester
41: {
42: get { return semester; }
43: set { semester = value; }
44: }
45:
46: public override bool Equals(object obj)
47: {
48: Enrolment that = obj as Enrolment;
49: if (that == null)
50: return false;
51: return studentNumber == that.StudentNumber && courseCode.Equals(that.CourseCode);
52: }
53:
54: public override int GetHashCode()
55: {
56: return courseCode.GetHashCode();
57: }
58: }
59: public class StudentDTO
60: {
61: private string studentName;
62: private string courseDescription;
63:
64: public StudentDTO() { }
65:
66: public string Name
67: {
68: get { return studentName; }
69: }
70:
71: public string Description
72: {
73: get { return courseDescription; }
74: }
75: }
What we can do is to retrieve StudentDTO from Presenter by querying from Repository. Code is elegant and beautiful. How sexy NHibernate is!!
