FetchOnlyAttribute Class

Applied to persistent properties and fields. When applied, specifies that the target property or field value can be loaded from the database but should not be saved (should not be included in the INSERT and UPDATE SQL statements).

Namespace: DevExpress.Xpo

Assembly: DevExpress.Xpo.v21.1.dll

NuGet Package: DevExpress.Xpo

Declaration

C#

[AttributeUsage(AttributeTargets.Property | AttributeTargets.Field, Inherited = true)]
public sealed class FetchOnlyAttribute :
    Attribute

VB.NET

<AttributeUsage(AttributeTargets.Property Or AttributeTargets.Field, Inherited:=True)>
Public NotInheritable Class FetchOnlyAttribute
    Inherits Attribute

Remarks

This attribute is helpful when you need to map XPO class properties/fields to:

• computed database columns (when it is inefficient to implement them as read-only using PersistentAliasAttribute);
• auto-increment database columns that are not primary keys (for example, rowversion).

You can decorate a property/field with the FetchOnlyAttribute directly in code or using the Data Model Designer.

C#

using DevExpress.Xpo;

// ...  
[FetchOnly]
[Persistent("Total")]
private double _total;

[PersistentAlias(nameof(_total))]
public double Total {
    get { return _total; }
}
// ...  

VB.NET

Imports DevExpress.Xpo

' ...  
<FetchOnly, Persistent(nameof(Total))>
Private _total As Double

<PersistentAlias(nameof(_total))>
Public ReadOnly Property Total() As Double
    Get
        Return _total
    End Get
End Property
' ...

The designer applies this attribute when you enable the Fetch Only option. In the metadata (see XPTypeInfo), the XPMemberInfo.IsFetchOnly property returns True for members with this attribute.

Note

In a NestedUnitOfWork, the attribute’s target property/field value is not passed to the parent session.

Inheritance

Object

Attribute

FetchOnlyAttribute