How do you convert a Data Table Column to a List of string in VB.Net

Question

I have a Data Table with one column in it. I want to take that Data Table column and either convert it straight into a list of string.

I have tried using a For Each loop to get each data row item and write it to a list of string but when I'm looking at the output after using a Write Line, I get "System.Data.DataRow" instead of the row value which would be something like "11363".

Here is the data table. The row title is "Codes". The values below the column title are what I want added to a list of string.

[Codes
11361
11362
11363
15509
16494
16898
17333
19550
]

Here is the code that I have tried to use that is not working for me.

ForEach row As DataRow in ExampleDataTable
    If Not String.IsNullOrEmpty(row.ToString.Trim)
        ExampleList.Add(row.ToString)
    End If
Next

ForEach item As String in ExampleList
    Console.WriteLine(item)
Next

The output I get from that after using a For Each loop to print out everything in the list is:

System.Data.DataRow
System.Data.DataRow
System.Data.DataRow
System.Data.DataRow
System.Data.DataRow
System.Data.DataRow
System.Data.DataRow
System.Data.DataRow

What I want it to output is:

11361
11362
11363
15509
16494
16898
17333
19550

Can anyone help me out with this? I've read a lot of posts now on Stack Overflow as well as MSDN and I'm just not able to figure this one out.

Answer 1

Jon was probably down voted because that code wont compile. He forgot some things, such as including the Rows collection for iteration, and when checking the null he is actually checking the row itself, not the value.

    Dim StrList As New List(Of String)
    For Each DtRow As DataRow In dt.Rows
        If DtRow("ColumnName") IsNot Nothing Then
            StrList.Add(DtRow("ColumnName").ToString)
        End If
    Next

Your question was probably down voted becuase a simple google search produces maybe 10 results how to do this, now 11.

This will probably be down voted because its not a comment, so maybe up vote it because I need 4 pts to start leaving comments.

Answer 2

Don't add the whole row. Add the column by using row.item(colName or ColNumber)

Dim ExampleList As New List(Of String)
For Each row As DataRow In ExampleDataTable.Rows
    If Not String.IsNullOrEmpty(row.Item("Codes")) Then
        ExampleList.Add(row.Item("Codes").ToString)
    End If
Next

EDIT: Code above now corrected to compile OK. A LINQ version would be:

Dim ExampleList = (From rw As DataRow In ExampleDataTable.Rows
                   Where Not String.IsNullOrEmpty(rw.Item("Codes"))
                   Select rw.Item("Codes")
                   ).ToList()

Answer 3

Enumerable.Range(0,dt.ColumnCount).Select(Function(x) dt.Columns(x).ToString).ToList()