Forms extension: Register override lookup method on datasource field

on

Coc class of the form 

/// <summary>
///  	Extension of the <c>FormName</c> form
/// </summary>
[ExtensionOf(formStr(FormName))]
final class FormName_Extension
{
    public void init()
    {
        next init();

        DatasourceName_ds.object(fieldNum(TableName, FieldName))     
            .registerOverrideMethod(formMethodStr(FormDataObject, lookup), formMethodStr(FormName, lookupItemId), this);    
              
    }
    
    public void lookupItemId(FormStringControl _formControl)   
    {	
        InventTable::lookupItem(_formControl, false);
    }
}