Can't change combine DiscriptionField of Selector Stock Item

@mrthanhkhoi 

This is the original field definition

		#region InventoryID
		public abstract class inventoryID : PX.Data.BQL.BqlInt.Field<inventoryID>
		{
			public class InventoryBaseUnitRule : 
				InventoryItem.baseUnit.PreventEditIfExists<
					Select<SOLine,
					Where<inventoryID, Equal<Current<InventoryItem.inventoryID>>,
						And<lineType, In3<SOLineType.inventory, SOLineType.nonInventory>,
						And<completed, NotEqual<True>>>>>>
			{ }
		}
		protected Int32? _InventoryID;
		[SOLineInventoryItem(Filterable=true)]
		[PXDefault()]
		[PXForeignReference(typeof(FK.InventoryItem))]
		public virtual Int32? InventoryID
		{
			get
			{
				return this._InventoryID;
			}
			set
			{
				this._InventoryID = value;
			}
		}
		#endregion

The attribute [SOLineInventoryItem] includes the PXSelector definition, which is the one that manages the SubstituteKey and DescriptionField properties.

You could redefine that attribute in the following way:

  [PXDBInt()]
  [PXUIField(DisplayName = "Inventory ID", Visibility = PXUIVisibility.Visible)]
  [PXRestrictor(typeof(Where<InventoryItem.itemStatus, NotEqual<InventoryItemStatus.noSales>,
              Or<Where2<Where<Current<SOOrderType.behavior>, Equal<SOOrderTypeConstants.salesOrder>,
                And<Current<SOOrderType.iNDocType>, Equal<INTranType.transfer>>>,
                Or<Current<SOLine.operation>, Equal<SOOperation.receipt>>>>>), PX.Objects.IN.Messages.ItemCannotSale)]
  public class SOLineTESTInventoryItemAttribute : CrossItemAttribute
  {
    public SOLineTESTInventoryItemAttribute()
      : base(typeof(Search<InventoryItem.inventoryID, Where<Match<Current<AccessInfo.userName>>>>), typeof(InventoryItem.inventoryCD), typeof(InventoryItemExt.usrCustomField), INPrimaryAlternateType.CPN)
    {
    }
  }

Notice that the second to last parameter of the constructor implements InventoryItemExt.usrCustomField, instead of the original InventoryItem.descr

Then the field can be redefined in the SOOrderEntry graph via CacheAttached in order to use the new Attribute, instead of the original one:

  public class SOOrderEntry_Extension : PXGraphExtension<PX.Objects.SO.SOOrderEntry>
  {
    [SOLineTESTInventoryItem(Filterable=true)]
    [PXDefault()]
    public void SOLine_InventoryID_CacheAttached(PXCache sender) { }  
}

Result

Attached is a customization project example for additional references