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.

Domino Development Best Practice

Over the next few weeks, I will share best practice as a developer when I am developing Notes/Domino applications.

I will start the series by sharing some basic development styles which I adhere to:

- Always declare variables in a hierarchy and keep Domino object declaration different from other variables, i.e.,

Dim session as NotesSession

Dim db as NotesDatabase

Dim vwCustomer as NotesView

Dim customerDoc as NotesDocument

Dim strFirstName as string, strLastName as string

Dim varNames as Variant

As you can see - session comes first, then db, then view etc etc. Also notice that the string and other variables are kept separate from Notes objects.

- Make sure to tab and comment your code properly for your own benefit - trust me, when you come back to your own code in a year's time, without proper comments, you will have a hard time understanding why you did something in the first place.

- Try to generalize sub-routines as much as possible. I try to follow a simple rule, when a single method or function gets too big to handle, start breaking it up into smaller pieces - divide and conquer.

- Always try to simplify code in order to hide complexity and make your life simpler, i.e.:

BEFORE:

Sub AttachFile (ndDoc As NotesDocument, strFileName As String, strRichTextFieldName As String)

Dim object

Dim strFilename As String

strFilename = Dir$(filename)

If (strFilename <> "") Then

Dim rtitem As NotesRichTextItem

If ndDoc.HasItem(strRichTextFieldName) Then

Set rtitem = ndDoc.GetFirstItem(strRichTextFieldName)

Else

Set rtitem = New NotesRichTextItem( ndDoc, strRichTextFieldName )

End If

Set object = rtitem.EmbedObject ( EMBED_ATTACHMENT, "", strFileName)

End If

End Sub

AFTER:

Sub AttachFile (ndDoc As NotesDocument, strFileName As String, strRichTextFieldName As String)

Dim object

If FileExists(strFileName) Then

Dim rtitem As NotesRichTextItem

If ndDoc.HasItem(strRichTextFieldName) Then

Set rtitem = ndDoc.GetFirstItem(strRichTextFieldName)

Else

Set rtitem = New NotesRichTextItem( ndDoc, strRichTextFieldName )

End If

Set object = rtitem.EmbedObject ( EMBED_ATTACHMENT, "", strFileName)

End If

End Sub

Function FileExists(Byval filename As String) As Boolean

Dim strFilename As String

On Error Resume Next

strFilename = Dir$(filename)

FileExists = (strFilename <> "")

End Function

As you can see you will have to do some thinking in order to figure out what this line of code does in the before example:

strFilename = Dir$(filename)

If (strFilename <> "") Then

but it's obvious in the after example.

JS Technique (DHTML)

node.style.display = (node.style.display == 'block') ? 'none' : 'block';

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