TableView - Setting data type to TableView columns

I figured it out.

The problem happens if you try to add visible headers. The minute you call tableView.Rows.Add, the system will ignore the isHeader property and just assume that any cell in the row must conform to the datatype you've declared for the column (you cannot override datatype per row, it's either the entire column or nothing; that also means you can save yourself the trouble to assign it to every cell).

So really there are only two options at this point: strings everywhere, or no headers in your TableView.

Here's a working implementation that renounces headers:

	Dim dt As New DataTable("FakeData")
	dt.Columns.Add("SomeDescription", GetType(String))
	dt.Columns.Add("DecimalNumber", GetType(Decimal))
	dt.Rows.Add("Row one", 10.5)
	dt.Rows.Add("Row Two", 11.0)

	Dim tv As TableView = New TableView()
	tv.CanModifyData = False
	
	' column definitions
	Dim tvHeader As New TableViewRow()
	For Each dtCol As DataColumn In dt.Columns
		Dim tvCol1 As New TableViewColumn()
		tvCol1.Name = dtCol.ColumnName
		tvCol1.Value = dtCol.ColumnName
		If tvCol1.Name.XFEqualsIgnoreCase("DecimalNumber") Then
			tvCol1.DataType = XFDataType.Decimal
		End If
		tvCol1.IsHeader = True
		tv.Columns.Add(tvCol1)
		' uncomment this to break
		' tvHeader.Items.Add(tvCol1.Name, tvCol1)
	Next
	' uncomment this to break
	' tv.Rows.Add(tvHeader)
		
	' data
	For Each row In dt.Rows
		Dim tvDataRow1 As New TableViewRow()
		For Each tvCol As TableViewColumn In tv.Columns
			Dim col As New TableViewColumn()
			col.Name = tvCol.Name
			col.Value = row.Item(tvCol.Name)
			col.IsHeader = False
			tvDataRow1.Items.Add(col.Name, col)
		Next
		tv.Rows.Add(tvDataRow1)
	Next
	Return tv

 I would probably consider this a bug, or at the very least something that should be documented. Feel free to submit it and claim the glory 😉