Initialize a Property After Creating an Object (EF 6)

• Jun 25, 2021
• 3 minutes to read

In this lesson, you will learn how to set the default value for a particular property of a business class. For this purpose, the Priority property will be added to the DemoTask class created in the Set a Many-to-Many Relationship (EF 6) lesson. To initialize it, assign a value to this property in the constructor.

Note

Before proceeding, take a moment to review the following lessons:

• Inherit from the Business Class Library Class (EF 6)
• Set a Many-to-Many Relationship (EF 6)

• Add the Priority property to the DemoTask class and declare the Priority enumeration, as shown below:

  C#

  namespace MySolution.Module.BusinessObjects {
      //...
      public class DemoTask : Task {
          //...
          public Priority Priority { get; set; }
      }
  
      public enum Priority {
          Low = 0,
          Normal = 1,
          High = 2
      }
  }
  

  VB.NET

  Public Class DemoTask
      Inherits Task
      '...
      Public Property Priority() As Priority
  End Class
  
  Public Enum Priority
      Low = 0
      Normal = 1
      High = 2
  End Enum
  

• In the Module.cs (Module.vb) file, register the Priority enumeration type in the constructor of your ModuleBase descendant using the EnumProcessingHelper.RegisterEnum method as follows.

  C#

  using DevExpress.Data.Filtering;
  //...
  public sealed partial class MySolutionModule : ModuleBase {
      public MySolutionModule() {
          InitializeComponent();
          EnumProcessingHelper.RegisterEnum(typeof(MySolution.Module.BusinessObjects.Priority));
          //...
      }
      //...
  }
  

  VB.NET

  Imports DevExpress.Data.Filtering
  '...
  Partial Public NotInheritable Class MySolutionModule
      Inherits ModuleBase
      Public Sub New()
          InitializeComponent()
          EnumProcessingHelper.RegisterEnum(GetType(MySolution.Module.BusinessObjects.Priority))
          '...
      End Sub
      '...
  End Class
  

• Use the code below to initialize the newly added Priority property when a DemoTask object is created.

  C#

  public class DemoTask : Task {
      public DemoTask() : base() {
          //...
          Priority = Priority.Normal; 
      }
      //...
  }
  

  VB.NET

  Public Class DemoTask
      Inherits Task
      Public Sub New()
          MyBase.New()
          '...
          Priority = Priority.Normal
      End Sub
      '...
  End Class
  

  The constructor will be executed when the new DemoTask object is created. As a result, the Priority property will be initialized with the specified value.

• Run the WinForms or ASP.NET Web Forms application. Create a new DemoTask object by selecting DemoTask in the drop-down list of the New () button. (In the Detail View that represents the newly created DemoTask object, note that the Priority property is set to Normal, as declared in the code above.) Notice that the enumeration property is automatically displayed by the combo box editor.

  

You can see the code demonstrated in this lesson in the MySolution.Module | Business Objects | DemoTask.cs (DemoTask.vb) file of the EF Demo (Code First) installed with XAF. By default, the EF Demo (Code First) application is installed in %PUBLIC%\Documents\DevExpress Demos 21.2\Components\eXpressApp Framework\EFDemoCodeFirst.

 

Next Lesson: Implement Dependent Reference Properties (EF 6)