DataSet.WriteXml

[Joe]

I noticed when using the WriteXml method that it doesn't include expression
columns. Is there some way to get these written too?

Thanks,
Joe

 

[Mark Ashton]

A column won't be written out of it has MappingType.Hidden, check the
ColumnMapping value for the expression columns in question

'here is a sample that shows expressions will be written unless the
ColumnMapping is set
Sub Main()
Dim ds As New DataSet("MyDataSet")
Dim dt As DataTable = ds.Tables.Add("MyTable")
Dim dc As DataColumn = dt.Columns.Add("MyColumn")
Dim ep As DataColumn = dt.Columns.Add("MyExpression")
ep.Expression = "MyColumn + ' world'"
'ep.ColumnMapping = MappingType.Hidden
Dim dr As DataRow = dt.NewRow
dr.Item(dc) = "hello"
dt.Rows.Add(dr)
ds.WriteXml(Console.Out)
End Sub