Hello everybody,

today I want to fulfill my promise that I gave to one of my readers. 

He left at mine blog following question:

How do we use required<> in place of current<> and pass some string constant for selector? That question was asked in context of this article. 

That is good question and I also want to add that answer on it will be at least to some degree disappointing. First of all, if you work with selectors, you can't use Required. Required is intended for use in Graphs.

But if you want to use some constant filtering conditions, you don't need Required attribute at all. You can use mechanism of Constants, which works perfectly without Required. 

Take a look at the following declaration:

public static class OrderTypes
{
    public const string N = "N";
    public const string C = "C";
 
    public class closed : Constant<String>
    {
        public closed()
            : base(C)
        {
        }
    }
 
    public class open : Constant<String>
    {
        public open() : base(N)
        {
        }
    }
}

As you can see, we declared two cosntants for order types: N and C.

Below goes code that shows how can you create selector that will filter Orders by OrderTypes with usage of those constants:

class Test : PXCacheExtension<SOOrder>
{
    #region UsrPreviousTermsId
 
    public abstract class usrPreviousTermsId : IBqlField
    {
    }
 
    [PXSelector(typeof(Search<SOOrder.orderNbr, Where<SOOrder.status, Equal<OrderTypes.closed>>>))]
    [PXUIField(DisplayName = "Linked sales order")]
    [PXDBString(10, IsUnicode = true)]
    public string UsrLinkedSalesOrder { get; set; }
 
    #endregion
}

Such code will give you selector that give you a list of orders with status closed. Also this sample of code shows that for selector you don't need Required in order to filter by some constant value.