Lotus Notes Validation

This week we will look at how we can handle validation within Lotus Notes using LotusScript.

Here is a class I have written which defines some basic validation routines:

' Copyright (c) Pipalia IT Consultants 2010

' Please keep the above copyright line, if you decide to use this class in your code

Class ValidationError

strErrorMsg() As String ' Array to store messages

counter As Integer

' Initiate the queue

Sub New()

counter = 0

End Sub

' Add error to an array

Sub AddError(strMsg As String)

Redim Preserve strErrorMsg(counter)

strErrorMsg(counter) = strMsg

counter = counter + 1

End Sub

' get all error messages

Function GetError() As String

Dim strError As String

Forall msg In strErrorMsg

If strError = "" Then

strError = msg

Else

strError = strError + Chr(13) + msg

End If

End Forall

GetError = strError

End Function

' determine whether an error has been raised

Function IsError() As Boolean

If counter = 0 Then

IsError = False

Else

IsError = True

End If

End Function

' check if field value is empty

Sub EmptyFieldError(strFieldVal As String, strMsg As String)

If Trim(strFieldVal) = "" Then

AddError(strMsg)

End If

End Sub

' check if given value (converted to single data-type) is positive

Sub PositiveValueCheck(strFieldVal As String, strMsg As String)

Dim sFieldVal As Single

If Trim(strFieldVal) <> "" Then

If Isnumeric(strFieldVal) Then

sFieldVal = Csng(strFieldVal)

If sFieldVal <>

AddError(strMsg)

End If

Else

AddError(strMsg)

End If

End If

End Sub

Sub IsGreaterThanZero(strFieldVal As String, strMsg As String)

Dim sFieldVal As Single

If Trim(strFieldVal) <> "" Then

If Isnumeric(strFieldVal) Then

sFieldVal = Csng(strFieldVal)

If sFieldVal <= 0 Then

AddError(strMsg)

End If

Else

AddError(strMsg)

End If

End If

End Sub

' Check if given card number is a numeric value

Sub IsCardNumber(strFieldVal As String, strMsg As String)

Dim strCharacter As String

For x = 1 To Len(strFieldVal)

strCharacter = Mid(strFieldVal, x, 1)

If (Asc(strCharacter) > 47 And Asc(strCharacter) <>

' Numeric value

Else

AddError(strMsg)

Exit For

End If

Next

End Sub

' Raise an error if field value length is higher than maximum

Sub CheckValueLength(strFieldVal As String, intSize As Integer, strMsg As String)

If Len(strFieldVal) > intSize Then

AddError(strMsg)

End If

End Sub

' Used to add any generic error message to the list

Sub GeneralError(strMsg As String)

AddError(strMsg)

End Sub

End Class

We will look at what this code does and how to use it during validation in the next session.

Error handling in Notes

If we were using .NET or Java, we could easily handle errors using Try and Catch, but that's not the case in Notes, so it's important to know where exactly the error occurred - which module, what line and where it was called from. Knowing this information helps us resolve the problem in a quick and efficient manner. Let's now look at how we can achieve something similar in Notes:

Msgbox Lsi_info(2) & " called by " & Lsi_info(12) & "(" & Lsi_info(430) & "): " & Error$ & " - Line: " & Cstr(Erl), 16, "Title"

I read an interesting article on Dominopower (http://www.dominopower.com/issues/issue200606/00001780001.html), which lead me to update my error handling code.

So what does it do you may ask:

1) Lsi_info(2) - returns the current module/sub/function name

2) Lsi_info(12) - returns the parent module that called this routine or function.

3) Lsi_info(430) - returns the line number in the calling module that called this module.

It's always a good idea to log all your errors in a database as well as displaying a generic error message to the user. This is where Julian Robichaux's OpenLog (http://www.openntf.org/Projects/pmt.nsf/ProjectLookup/OpenLog) template comes in handy.