[RESOLVED] Unable to cast object of type 'System.String' to type 'System.String[]'.

im trying to retrieve contents of a field from the database , but im getting :

 

Unable to cast object of type 'System.String' to type 'System.String[]'.

below is my code

Private Function createpath() As String

       
        Dim conread As New SqlConnection("Data Source=.;Integrated Security=True;MultipleActiveResultSets=True;Initial Catalog=CMS")
        Dim sqlgetpath As New SqlCommand
        conread.Open()

        sqlgetpath = New SqlCommand("SELECT FileName from NewLis", conread)

        reader = sqlgetpath.ExecuteReader

        reader.Read()


        Dim listfilename() As String = reader("FileName")



        For Each listFile As String In listfilename

            Dim writer As New System.IO.StreamWriter("d:\nf\aio.txt", True)
            writer.WriteLine(reader("FileName").ToString())

        Next

        reader.Close()
        conread.Close()

        Return listfilename.ToString()


    End Function

hope someone can help !!

Use the following code:

Dim conread As New SqlConnection("Data Source=.;Integrated Security=True;MultipleActiveResultSets=True;Initial Catalog=CMS")
        Dim sqlgetpath As New SqlCommand
        conread.Open()

        sqlgetpath = New SqlCommand("SELECT FileName from NewLis", conread)

        reader = sqlgetpath.ExecuteReader
        Dim allFiles as String
        allFiles=""
        
        Dim writer As New System.IO.StreamWriter("d:\nf\aio.txt", True)
        Dim s as string
        while (reader.Read())
            s=reader("FileName").ToString()
            allFiles=allFiles + s + ","
            writer.WriteLine(s)
        End while
        reader.Close()
        conread.Close()
         writer.close()

        Return allFiles

You can go with below code:

Private Function createpath() As String
        Dim conread As New SqlConnection("Data Source=.;Integrated Security=True;MultipleActiveResultSets=True;Initial Catalog=CMS")
        Dim sqlgetpath As New SqlCommand
        sqlgetpath = New SqlCommand("SELECT FileName from NewLis", conread)
        Dim custDA As SqlDataAdapter = New SqlDataAdapter
        custDA.SelectCommand = sqlgetpath
        conread.Open()
        Dim listfilename As DataTable = New DataTable
        custDA.Fill(listfilename)

        For Each listFile As DataRow In listfilename.Rows
            Dim writer As New System.IO.StreamWriter("d:\nf\aio.txt", True)
            writer.WriteLine(listFile("FileName").ToString())
        Next listFile
        conread.Close()
        Return listfilename.ToString()
    End Function

Don't forget to add,

Imports System.Data.SqlClient
Imports System.Data

It's called boxing ... cuz it's already string

For Each listFile As String In listfilename
Dim writer As New System.IO.StreamWriter("d:\nf\aio.txt", True)
writer.WriteLine(listFile)
Next