How do implement dynamic data validation e.g. as Excel VBA-function? - excel

Question

Data validation in Excel is a helpful way to verify user input in Excel. The standard way is to (1) define somewhere (e.g. on an auxillary sheet) a list with possible input values and (2) then choose that range in the Source field. Alternatively, one can also directly type in the different options in that field, e.g:
My question: How do we make the data-validation list dynamic?
What I tried so far is to enter a (possibly user-defined VBA) formula returning a list of strings in into the field Source of the data-validation dialog, for example
=INDEX({"New","Mint","Very Good","Good","Acceptable","Poor"},{1,RANDBETWEEN(1,6)})
However, this approach does not work as it leads to an error message
You may not use reference operators (such as unions, intersections,
and ranges) or array constants for Data Validation criteria.
What do I miss? Which (possibly more elegant) way of making the Source of the data validation dynamic do you suggest?
Edit: My concrete problem:
On all (but the first) tab sheet, I have a cell called myTest and the list of allowed values is for a cell on the first tab, where I want be able from the list composed of all possible values of myTest.
References:
Debra Dalgleish: "Create Dependent Drop Down Lists" at contextures.com
Dynamic Data Validation in Excel (Non-VBA!)

Answer 1

You can use something like this in the first sheet's code module:
Private Sub Worksheet_Activate()
Const LIST_COL As Long = 26
Dim sht As Worksheet, i As Long
i = 1
Me.Columns(LIST_COL).ClearContents '<< clear current list
For Each sht In ThisWorkbook.Worksheets '<< collect all the values
If sht.Name <> Me.Name Then
Me.Cells(i, LIST_COL).Value = sht.Range("myTest").Value
i = i + 1
End If
Next sht
End Sub
It will collect the values from the other sheets into a range you can reference for the validation list.
Note: if the other sheet's values are updated via code or formulas (ie. do not require you to go to each sheet to change values) then you'd need to do a bit more work.
EDIT - this is more convoluted but works more reliably, since it gets run whenever you click on the validation drop-down
1. Put this in a regular module (edit as required):
'A function to return a range containing the
' various values which need to appear in the validation list
Public Function ListCompile() As Range
Const LIST_COL As Long = 26 '<< create the list in Col Z
Dim sht As Worksheet, i As Long
i = 1
Sheet1.Columns(LIST_COL).ClearContents
For Each sht In ThisWorkbook.Worksheets
If sht.Name <> Sheet1.Name Then
Sheet1.Cells(i, LIST_COL).Value = sht.Range("myTest").Value
i = i + 1
End If
Next sht
'return the list we just created
Set ListCompile = Sheet1.Cells(1, LIST_COL).Resize(i, 1)
End Function
Note: I'm using the codename for Sheet1 (which might be different from the tab name). You can see the code name in the VB editor Project Explorer.
2. Define a named range "tester" with "RefersTo" equal to ListCompile()
3. Finally set your data validation list range to: =tester

Answer 2

Assuming:
Your list is in column A
There is no header
You could make data-validation with a dynamic list using this formula as source:
=OFFSET(A1,0,0,COUNTA(A:A),1)
Edit: below is an image of an example using the formula above in data-validation applied to cell B1:
If you can somehow join your values in a single column, this is a possibility.