Understanding Iterators, Part 2: Listing 1

The Visual Basic function iterator method.

  Dim svcUri As Uri = New Uri("http://www.pluralsight-training.net/odata/")

  Public Iterator Function GetCourseModuleForCategoryIterator(categoryName) As IEnumerable(Of CourseWithModules)
      Dim provider = New PluralsightService.CourseProvider(svcUri)
      Dim courses = GetCoursesForCategory(categoryName)
      For Each course In courses
          Dim courseWithModules = New CourseWithModules
          courseWithModules.Course = course
          courseWithModules.Modules = GetModulesForCourse(course.Name)
          Yield courseWithModules
      Next
      Return
  End Function

  Public Function GetCoursesForCategory(CategoryName As String) As List(Of PluralsightService.Course)
      Dim provider = New PluralsightService.CourseProvider(svcUri)
      Dim CategoryCourses = provider.Courses.Where(Function(item) item.Category = CategoryName).ToList
      Return CategoryCourses
  End Function

  Public Function GetModulesForCourse(CourseName As String) As List(Of PluralsightService.CourseModule)
      Dim provider = New PluralsightService.CourseProvider(svcUri)
      Dim courseWithModules = provider.Courses.Expand("Modules").Where(Function(item) item.Name = CourseName).Single
      Dim modules = courseWithModules.Modules.ToList
      Return modules
  End Function

  Public Class CourseWithModules
      Public Course As PluralsightService.Course
      Public Modules As List(Of PluralsightService.CourseModule)
  End Class

About the Author

Joe Kunk is a Microsoft MVP in Visual Basic, three-time president of the Greater Lansing User Group for .NET, and developer for Dart Container Corporation of Mason, Michigan. He's been developing software for over 30 years and has worked in the education, government, financial and manufacturing industries. Kunk's co-authored the book "Professional DevExpress ASP.NET Controls" (Wrox Programmer to Programmer, 2009). He can be reached via email at joekunk@ajboggs.com.