XAF : Set Default Property For Object Attribute

Here we will set a default value for a property of a business class, In this example we will set the default 'Priority' property in DemoTask to 'Normal' state. To do this, first we want to build DemoTask Class with 'Priority' property:

   1:  Public Class DemoTask

   2:      Inherits Task

   3:      ' ...

   4:      Private fPriority As Priority

   5:      Public Property Priority() As Priority

   6:          Get

   7:              Return fPriority

   8:          End Get

   9:          Set(ByVal value As Priority)

  10:              SetPropertyValue("Priority", fPriority, value)

  11:          End Set

  12:      End Property

  13:      '...

  14:  End Class

• 'Priority' property added to DemoTask class

   1:  Public Enum Priority

   2:      Low = 0

   3:      Normal = 1

   4:      High = 2

   5:  End Enum

• Declaration of 'Priority' enumeration.

To initialize 'Priority' property when a DemoTask object is created, we override the AfterConstruction method as shown below:

   1:  Public Class DemoTask

   2:      Inherits Task

   3:      '...

   4:      Public Overrides Sub AfterConstruction()

   5:          MyBase.AfterConstruction()

   6:          Priority = Priority.Normal

   7:      End Sub

   8:      '...

   9:  End Class

This method will be executed when the new DemoTask object is created. So, the 'Priority' property will be initialized with the specified value.


[eXpressApp Framework]