Question

I’m currently working on a project that involves a CSV file. I initially was using Microsoft.Jet.OLEDB.4.0 to extract everything. However, there are large numbers that sometimes don’t make it over and are “blanked” out.

So, after doing some research, I was able to find an example where I could stuff everything into a list. For example:

Dim lstExample As New List(Of String)().  

From here I could use a SteamReader to grab the csv file and store it. Since the first 3 lines are garbage, I’m skipping those and reading all the rest of the lines along with about 30 columns of comma delimited data.

My problem now is that I’m unable to get the lstExample into either a dataset or datatable. I even manually created a list and it still errors out.

The error occurs on this line:

dataRow(i) = itemProperties(i).GetValue(item, Nothing) saying "Parameter count mismatch."

Any ideas to get a List into dataset/datatable?

   Public Shared Sub ManualReadCSVFile(ByVal strFilePath As String)
    Dim lstExample As New List(Of String)()

    Using reader = New StreamReader("c:\SFTP_Target\ATL-536437.csv")
        For i As Integer = 0 To 2
            reader.ReadLine()
        Next

        While Not reader.EndOfStream
            Dim line = reader.ReadLine()
            Dim values = line.Split(",")

            lstExample.Add(values(0))

        End While

        reader.Dispose()
    End Using

    'Dim list As New List(Of String)(New String() {"nile", _
    '    "amazon", _
    '    "yangtze", _
    '    "mississippi", _
    '    "yellow"})

    Dim dsTest As New DataSet
    dsTest = CreateDataSet(lstExample)
    'dsTest = CreateDataset(list)

End Sub

Public Shared Function CreateDataSet(Of T)(ByVal list As List(Of T)) As DataSet
    'list is nothing or has nothing, return nothing (or add exception handling)
    If list Is Nothing OrElse list.Count = 0 Then
        Return Nothing
    End If

    'get the type of the first obj in the list
    Dim obj = list(0).[GetType]()

    'now grab all properties
    Dim properties = obj.GetProperties()

    'make sure the obj has properties, return nothing (or add exception handling)
    If properties.Length = 0 Then
        Return Nothing
    End If

    'it does so create the dataset and table
    Dim dataSet = New DataSet()
    Dim dataTable = New DataTable()

    'now build the columns from the properties
    Dim columns = New DataColumn(properties.Length - 1) {}
    For i As Integer = 0 To properties.Length - 1
        columns(i) = New DataColumn(properties(i).Name, properties(i).PropertyType)
    Next

    'add columns to table
    dataTable.Columns.AddRange(columns)

    'now add the list values to the table
    For Each item In list
        'For Each item As T In list
        'create a new row from table
        Dim dataRow = dataTable.NewRow()

        'now we have to iterate thru each property of the item and retrieve it's value for the corresponding row's cell
        Dim itemProperties = item.[GetType]().GetProperties()

        For i As Integer = 0 To itemProperties.Length - 1
            dataRow(i) = itemProperties(i).GetValue(item, Nothing)
        Next

        'now add the populated row to the table
        dataTable.Rows.Add(dataRow)
    Next

    'add table to dataset
    dataSet.Tables.Add(dataTable)

    'return dataset
    Return dataSet
End Function

Answer 1

if you are simply trying to parse a csv file into .net objects try http://www.filehelpers.com. it’s a simple way to parse csv files into POCOs or datatables.