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ASP.NET - error - Value of type 'System.Collections.Generic.List(Of String)' cannot be converted

Posted on 2011-03-09
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Last Modified: 2012-05-11

the goal of this code is that on postback from the user selecting from a drop down menu...will go and find all phone numbers and
populate a grid...however, I get the following error:
--------------
line 81:

   " and  TO_NUMBER in ('" & String.Join(",", myList) & ")"
in the IDE...it has mylist underlined....

when I put the cursor overmylistThen it displays this error:
Value of type 'System.Collections.Generic.List(Of String)' cannot be converted to '1-dimensional array of String'.




Protected Sub DropDownList1_SelectedIndexChanged(ByVal sender As Object, ByVal e As System.EventArgs)
        Dim DDL_val As String
        Dim flag As String
        Dim TC_ID As String
        
        TC_ID = Session("SessionTC_ID")
        DDL_val = DropDownList1.Text
        flag = "dataset"
        
        Session("sessionDDL") = DropDownList1.Text
        
        
        
        ' -----------------------------------------------------------------------------
        ' DHAEST SOULTION FROM EE...
        ' http://www.experts-exchange.com/Programming/Languages/.NET/Q_26843829.html
        '
        
        
        
        Dim myList As List(Of String) = New List(Of String)
        
        Try

            
            Dim MyDropDown As DropDownList
           
            Dim myArray As New ArrayList()
            Dim dataReader As SqlDataReader
            Dim x As Integer = 0
            Dim sqlConnection As String
            
            TC_ID = Session("SessionTC_ID")
            MyDropDown = DropDownList1
            
               
            Using sqlConn As New SqlConnection
                sqlConnection = "Data Source=xx.xx.xx.xx;Initial Catalog=dcdff;Trusted_connection=true;"
                sqlConn.ConnectionString = sqlConnection
                Dim SQLstring As String = "SELECT * FROM campaign WHERE TC_ID = '" & TC_ID & "'" & _
   " AND campaign_name = '" & Session("sessionCAMP_NAME") & "'"
          
                sqlConn.Open()
                Using command As New SqlCommand(SQLstring, sqlConn)
                    dataReader = command.ExecuteReader(System.Data.CommandBehavior.CloseConnection)
                    If dataReader.HasRows Then
                        Do While dataReader.Read()
                            myList.Add(dataReader("TO_NUMBER").ToString())
                        Loop
                        
                    End If
                    dataReader.Close()
                    sqlConn.Close()
                End Using
            End Using
            
            myArray.Sort()

            MyDropDown.DataSource = myArray
            MyDropDown.DataBind()
        Catch ex As Exception
           
        End Try
          
        
               
        ' --------------------------------
        ' POPULATE THE TEXTBOX CONTROL..ON SELECTION FROM DROPDOWNLIST
        ' --------------------------------
        Try
            Dim Go_Message As TextBox
            Dim sqlConnection As String
          

            Using sqlConn As New SqlConnection
                sqlConnection = "Data Source=xx.xx.xx.xx;Initial Catalog=dffgxt;Trusted_connection=true;"
                sqlConn.ConnectionString = sqlConnection
                ' Dim SQLstring As String = "SELECT * FROM message_queue_recieve WHERE TC_ID = '" & TC_ID & "' and campaign_name = '" & DDL_val & "'" & _
                '" TO_NUMBER = '" & Session("sessonTO_NUMBER") & "'"
                Dim SQLstring As String = "SELECT * FROM message_queue_recieve WHERE TC_ID = '" & TC_ID & "'" & _
                " and  TO_NUMBER in ('" & String.Join(",", myList) & ")"
               
                Dim TblAdaptar As New SqlDataAdapter(SQLstring, sqlConn)
                Dim Tbl As New DataSet
                Tbl.Clear()
                Try
                    TblAdaptar.Fill(Tbl)
                    Me.GridView1.DataSource = Nothing
                    Me.GridView1.DataSource = Tbl
                    Me.GridView1.DataBind()
                Catch ex As Exception
                End Try
            End Using
        Catch ex As Exception
        End Try
        
        
        ' more code...

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Question by:GlobaLevel
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3 Comments
 
LVL 52

Expert Comment

by:Carl Tawn
ID: 35084387
You need to convert your list to an array.

i.e.
string.Join(",", myList.ToArray())

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Expert Comment

by:John Claes
ID: 35084450
that is indeed the reason :


Line 21:
        Dim myList As List(Of String) = New List(Of String)

Line 81 :
               " and  TO_NUMBER in ('" & String.Join(",", myList) & ")"


A generic List is indeed not accepted by the String.Join method

Use for Line 81 the folowig
               " and  TO_NUMBER in ('" & String.Join(",", myList.AsEnumerable()) & ")"

regards

poor beggar
0
 
LVL 52

Accepted Solution

by:
Carl Tawn earned 2000 total points
ID: 35084480
It can't use IEnumerable<> either! So as I said in my first post you need to call ToArray() on your List<>.
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