XPO Fields

• Aug 19, 2021
• 3 minutes to read

This feature is helpful for those who work with eXpress Persistent Objects. XPO Fields works in the PersistentBase descendants, where it automatically generates and maintains the XPO entities in Simplified Criteria Syntax based on the class members.

Follow the steps below to learn how to use this feature:

1. Create a PersistentBase descendant.

   C#

   class MyPersistentClass: PersistentBase {
       protected MyPersistentClass(Session session) : base(session) { }
   
   }
   

   VB.NET

   Friend Class MyPersistentClass
       Inherits PersistentBase
       Protected Sub New(ByVal session As Session)
           MyBase.New(session)
       End Sub
   End Class
   

2. Add the required fields and properties.

   C#

   public struct Occupation {
       public string Position;
       public string Team;
   }
   class MyPersistentClass: PersistentBase {
       protected MyPersistentClass(Session session) : base(session) { }
       public int age;
       public int Name { get; set; }
       public Occupation occupation;
       [NonPersistent]
       public bool Active { get; set; }
   }
   

   VB.NET

   Public Structure Occupation
       Public Position As String
       Public Team As String
   End Structure
   Friend Class MyPersistentClass
       Inherits PersistentBase
   
       Protected Sub New(ByVal session As Session)
           MyBase.New(session)
       End Sub
       Public age As Integer
       Public Property Name() As Integer
       Public occupation As Occupation
       <NonPersistent>
       Public Property Active() As Boolean
   End Class
   

3. Place the caret on the class name (MyPersistentClass in this case).
4. Press the Ctrl + . or Ctrl + ~ shortcut to invoke the Code Actions menu.

5. Select Update XPO Fields Class. This will generate or update the new FieldsClass inside the current class. The members with the [NonPersistent] attribute are not included in the FieldsClass class.

   C#

   class MyPersistentClass: PersistentBase {
       protected MyPersistentClass(Session session) : base(session) { }
       public int age;
       public int Name { get; set; }
       public Occupation occupation;
       [NonPersistent]
       public bool Active { get; set; }
   
       // Created/Updated: TestUser on TestPC at 6/14/17 8:20 PM
       public new class FieldsClass : PersistentBase.FieldsClass {
           public FieldsClass() { }
           public FieldsClass(string propertyName) : base(propertyName) { }
           public OperandProperty age {
               get { return new OperandProperty(GetNestedName("age")); }
           }
           public OperandProperty Name {
               get { return new OperandProperty(GetNestedName("Name")); }
           }
           public OperandProperty occupation_Position {
               get { return new OperandProperty(GetNestedName("occupation.Position")); }
           }
           public OperandProperty occupation_Team {
               get { return new OperandProperty(GetNestedName("occupation.Team")); }
           }
           public OperandProperty occupation {
               get { return new OperandProperty(GetNestedName("occupation")); }
           }
       }
       public new static FieldsClass Fields {
           get {
               if (ReferenceEquals(_Fields, null))
                   _Fields = new FieldsClass();
               return _Fields;
           }
       }
       static FieldsClass _Fields;
   }
   

   VB.NET

   Friend Class MyPersistentClass
       Inherits PersistentBase
   
       Protected Sub New(ByVal session As Session)
           MyBase.New(session)
       End Sub
       Public age As Integer
       Public Property Name() As Integer
       Public occupation As Occupation
       <NonPersistent>
       Public Property Active() As Boolean
   
       ' Created/Updated: TestUser on TestPC at 6/14/17 8:20 PM
       Public Shadows Class FieldsClass
           Inherits PersistentBase.FieldsClass
   
           Public Sub New()
           End Sub
           Public Sub New(ByVal propertyName As String)
               MyBase.New(propertyName)
           End Sub
           Public ReadOnly Property age() As OperandProperty
               Get
                   Return New OperandProperty(GetNestedName("age"))
               End Get
           End Property
           Public ReadOnly Property Name() As OperandProperty
               Get
                   Return New OperandProperty(GetNestedName("Name"))
               End Get
           End Property
           Public ReadOnly Property occupation_Position() As OperandProperty
               Get
                   Return New OperandProperty(GetNestedName("occupation.Position"))
               End Get
           End Property
           Public ReadOnly Property occupation_Team() As OperandProperty
               Get
                   Return New OperandProperty(GetNestedName("occupation.Team"))
               End Get
           End Property
           Public ReadOnly Property occupation() As OperandProperty
               Get
                   Return New OperandProperty(GetNestedName("occupation"))
               End Get
           End Property
       End Class
       Public Shadows Shared ReadOnly Property Fields() As FieldsClass
           Get
               If ReferenceEquals(_Fields, Nothing) Then
                   _Fields = New FieldsClass()
               End If
               Return _Fields
           End Get
       End Property
       Private Shared _Fields As FieldsClass
   End Class
   

You can configure different options of FieldsClass generation on the Editor | All Languages | Code Actions | Update XPO Fields Class options page.