Adding custom selector to a grid - acumatica

Question

I am having an issue with adding a selector for a custom field to a grid. I am having a lot of issues and I am a bit lost.
We need to add a selector to the "Documents to Apply" tab on the AR302000 screen (Finance -> Accounts Recievable -> Payments and Applications). This selector would be based off of a custom field we added to ARRegister.
public abstract class usrUploadDocNbr : IBqlField { }
[PXDBString(15)]
[PXUIField(DisplayName = Messages.UploadDocNbr)]
public virtual string UsrUploadDocNbr { get; set; }
I did not decorate this with the PXSelector tag since we use this field as with a textbox most of the time. From there, I added it to the AR302000 grid mentioned above, but the field was always disabled.When I looked at the fields available to add to the grid, there is ARInvoice__UsrUploadDocNbr and ARRegisterAlias__UsrUploadDocNbr. This kind of makes sense to me,but only a little bit.
When I tried to use either one of those fields, the row in the grid would always be read-only. From here, I figured I would try to add the field to ARAdj since this was the type of many of the fields in the grid. I added the following code:
public abstract class usrUploadDocNbr : IBqlField, IBqlOperand { }
[PXDBString(BqlField =typeof(ArRegisterExt.usrUploadDocNbr))]
[PXUIField(DisplayName = Messages.UploadBatchNbr, Enabled = true)]
[PXSelector(typeof(ARRegister.refNbr),
typeof(ARAdjust.ARInvoice.refNbr),
typeof(ARAdjust.ARInvoice.docDate),
typeof(ArRegisterExt.usrUploadDocNbr),
typeof(ARAdjust.ARInvoice.finPeriodID),
typeof(ARAdjust.ARInvoice.customerID),
typeof(ARRegister.customerLocationID),
typeof(PX.Objects.AR.Standalone.ARRegister.curyID),
typeof(ARRegister.curyOrigDocAmt),
typeof(ARRegister.curyDocBal),
typeof(PX.Objects.AR.Standalone.ARRegister.status),
typeof(ARAdjust.ARInvoice.dueDate),
typeof(ARAdjust.ARInvoice.invoiceNbr),
typeof(PX.Objects.AR.Standalone.ARRegister.docDesc),
SubstituteKey = typeof(ArRegisterExt.usrUploadDocNbr))]
public virtual string UsrUploadDocNbr { get; set; }
When I added this field, the selector worked, sort of. I was able to have the selector window open, but all the column names were the type name rather than the annotated name (as an example, usrUploadDocNbr rather than "Upload Doc. Nbr.").
But another issue popped up - the Refernce Nbr selector no longer works. We added the UsrUploadDocNbr to the Reference Nbr selector. The code is as follows:
[PXMergeAttributes(Method = MergeMethod.Append)]
[PXCustomizeSelectorColumns(
typeof(ARAdjust.ARInvoice.refNbr),
typeof(ARAdjust.ARInvoice.docDate),
typeof(ArRegisterExt.usrUploadDocNbr),
typeof(ARAdjust.ARInvoice.finPeriodID),
typeof(ARAdjust.ARInvoice.customerID),
typeof(ARRegister.customerLocationID),
typeof(PX.Objects.AR.Standalone.ARRegister.curyID),
typeof(ARRegister.curyOrigDocAmt),
typeof(ARRegister.curyDocBal),
typeof(PX.Objects.AR.Standalone.ARRegister.status),
typeof(ARAdjust.ARInvoice.dueDate),
typeof(ARAdjust.ARInvoice.invoiceNbr),
typeof(PX.Objects.AR.Standalone.ARRegister.docDesc))]
public virtual string AdjdRefNbr { get; set; }
The error that pops up reads (it does display the same thing twice in a single modal):
Invalid column name 'UsrUploadDocNbr'
Invalid column name 'UsrUploadDocNbr'
And at this point I am pretty lost. I am sure I am doing many things wrong, just not sure what it is.

Answer 1

First:
You should give typeof(Search<DAC.FIELD>) to the PXSelector as first parameter.
So change this line
[PXSelector(typeof(ARRegister.refNbr),
To
[PXSelector(typeof(Search<ARRegister.refNbr>),
Second:
Message
Invalid column name 'UsrUploadDocNbr'
mostly is being shown(if the field is decorated with PXDB... like attribute) when you have not created the field in the Database's Table.