DelayedAttribute(String) Constructor

Initializes a new instance of the DelayedAttribute class with the name of the field which stores the delayed property’s value.

Namespace: DevExpress.Xpo

Assembly: DevExpress.Xpo.v18.2.dll

Declaration

C#

public DelayedAttribute(
    string fieldName
)

VB.NET

Public Sub New(
    fieldName As String
)

Parameters

Name	Type	Description
fieldName	String	A String value which specifies the name of the field which stores the value of the delayed property. This value is assigned to the DelayedAttribute.FieldName property.

Remarks

By default, all properties and fields are restored from the storage when the object is loaded. For optimization purposes, it is possible to delay loading certain properties that are rarely used, or contain large amounts of data. Note that field loading cannot be delayed.

Example

The following example demonstrates how to delay the loading of the DelayedAttachment property and improve property value update performance, by enabling the DelayedAttribute.UpdateModifiedOnly property.

Note

This solution uses the XPDelayedProperty object explicitly and doesn’t raise property change notifications in all scenarios. You may need to explicitly call the Session.Save method after modifying the property value to save changes. Alternatively, implement the delayed property as shown in the Delayed Loading article.

C#

using DevExpress.Xpo;

public class Customer : XPObject {
   // ...
   private XPDelayedProperty document = new XPDelayedProperty();
   // Improve update performance for the property's value
   // by passing true as the attribute's
   // updateModifiedOnly parameter.
   [Delayed("document", true)]
   public Byte[] DelayedAttachment {
      get { return (Byte[])document.Value; }
      set { document.Value = value; }
   }
}

VB.NET

Imports DevExpress.Xpo

Public Class Customer
   Inherits XPObject
   ' ...
   Private document As XPDelayedProperty = New XPDelayedProperty()
   ' Improve update performance for the property's value
   ' by passing true as the attribute's
   ' updateModifiedOnly parameter.
   <Delayed("document", True)> _
   Public Property DelayedAttachment() As [Byte]()
       Get
           Return document.Value
       End Get
       Set
           document.Value = value
       End Set
   End Property
End Class