DateAdd() in Special Format - asp-classic

Question

I've tried all the ways I see to add a month to a certain date then return that in a specific format but I'm at a loss. Here's my code but I need to format it:
replace( formatdatetime( dateadd( "m" , 1 , request("date") ), 0 ) , "/" , "-" ) & "' )
request("date") is in yyyyy-dd-mm hh:mm:ss format and that's how I need the new date.

Answer 1

The following should work perfect:
replace( formatdatetime( dateadd( "m" , 1 , cDate(request("date")) ), 0 ) , "/" , "-" )
Notice the use of the cDate function to convert a value to a date explicitly.
Edit:
I removed last part of your code & "' ), it gave me an error otherwise.

Answer 2

When working with dates, it's especially important to take care of the proper data (sub)types. Feeding a string to a function that expects a date (and relying on 'VBScript - and your local settings - will do the right thing') is dangerous.
Using replace will never change the order of the date parts.
FormatDateTime depends on the local/regional settings and should be avoided as a sure path to disaster.
One way to solve this problem + most of all other problems concerning fancy formatting in VBScript is to use a .Net System.Text.StringBuilder:
Given Lib.vbs:
' Lib.vbs - simple VBScript library/module
' use
' ExecuteGlobal goFS.OpenTextFile(<PathTo\Lib.vbs>).ReadAll()
' to 'include' Lib.vbs in you main script
Class ToBeAShamedOf
Public a
Public b
End Class ' ToBeAShamedOf
Class cFormat
Private m_oSB
Private Sub Class_Initialize()
Set m_oSB = CreateObject("System.Text.StringBuilder")
End Sub ' Class_Initialize
Public Function formatOne(sFmt, vElm)
m_oSB.AppendFormat sFmt, vElm
formatOne = m_oSB.ToString()
m_oSB.Length = 0
End Function ' formatOne
Public Function formatArray(sFmt, aElms)
m_oSB.AppendFormat_4 sFmt, (aElms)
formatArray = m_oSB.ToString()
m_oSB.Length = 0
End Function ' formatArray
End Class ' cFormat
and main.vbs:
' main.vbs - demo use of library/module Lib.vbs
' Globals
Dim gsLibDir : gsLibDir = ".\"
Dim goFS : Set goFS = CreateObject("Scripting.FileSystemObject")
' LibraryInclude
ExecuteGlobal goFS.OpenTextFile(goFS.BuildPath(gsLibDir, "Lib.vbs")).ReadAll()
WScript.Quit demoDateFormat()
WScript.Quit main()
Function main()
Dim o : Set o = New ToBeAShamedOf
o.a = 4711
o.b = "whatever"
WScript.Echo o.a, o.b
main = 1 ' can't call this a success
End Function ' main
Function demoDateFormat()
Dim sD : sD = "2012-05-16 01:02:03" ' near future; not yyyyy!
Dim dtD : dtD = CDate(sD)
Dim dtDM : dtDM = DateAdd("m", 1, dtD)
Dim oFmt : Set oFmt = New cFormat
WScript.Echo oFmt.formatArray( _
" sD: {1}{0} dtD: {2}{0} dtDM: {3}{0}dtDM': {4}" _
, Array(vbCrLf, sD, dtD, dtDM, oFmt.formatOne("{0:yyyy-MM-dd hh:mm:ss}", dtDM)))
demoDateFormat = 0 ' seems to be decent
End Function ' demoDateFormat
you'll get:
cscript main.vbs
sD: 2012-05-16 01:02:03
dtD: 16.05.2012 01:02:03
dtDM: 16.06.2012 01:02:03
dtDM': 2012-06-16 01:02:03
(to be seen in the context of this answer)

Answer 3

This may help:
FormatDateTime(DateAdd("M",1,DateSerial(Left(request("date"),4),Mid(request("date"),9,2),Mid(request("date"),6,2))) & " " & Mid(request("date"),12,8),d,0)
It basically converts the string to a valid date in the native format, adds the 1 requested month and then rebuilds the string.
NOTE: request("date") looks as though it returns the current datetime so running it in this way may generate a final value that is a second or so out, if that's a problem then you will be better storing a static value in a variable, otherwise this should hopefully be ok.