Question

I am generating a javascript alert box from codebehind in asp.net(vb).

The code:

            Catch ex As Exception
                MesgBox("Error in uploading file due to following exception" & vbNewLine & ex.ToString)
                trans.Rollback()
            Finally
                conn.Close()
            End Try

The mesgbox function is as follows:

Private Sub MesgBox(ByVal sMessage As String)
    Dim msgedtble As String = sMessage.Replace("\", "\\")
    msgedtble = msgedtble.Replace(vbNewLine, "\n")
    Page.ClientScript.RegisterStartupScript(Me.GetType,
 "myScripts",
 "<script language='javascript'>alert('" & msgedtble & "');</script>")

End Sub

Now when exception is thrown, the following script is appended in the form tag of the client side html :

        <script language='javascript'>alert('Error in uploading file due to following exception\nSystem.Data.SqlClient.SqlException (0x80131904): Violation of UNIQUE KEY constraint 'IX_AccountMaster'. Cannot insert duplicate key in object 'dbo.AccountMaster'.\nThe statement has been terminated.\n   at System.Data.Common.DbDataAdapter.UpdatedRowStatusErrors(RowUpdatedEventArgs rowUpdatedEvent, BatchCommandInfo[] batchCommands, Int32 commandCount)\n   at System.Data.Common.DbDataAdapter.UpdatedRowStatus(RowUpdatedEventArgs rowUpdatedEvent, BatchCommandInfo[] batchCommands, Int32 commandCount)\n   at System.Data.Common.DbDataAdapter.Update(DataRow[] dataRows, DataTableMapping tableMapping)\n   at System.Data.Common.DbDataAdapter.UpdateFromDataTable(DataTable dataTable, DataTableMapping tableMapping)\n   at System.Data.Common.DbDataAdapter.Update(DataTable dataTable)\n   at UploadAccountMasterXl.Button1_Click(Object sender, EventArgs e) in C:\\Users\\ssaa\\Documents\\Visual Studio 2010\\WebSites\\Dpp2012\\UploadAccountMasterXl.aspx.vb:line 57');</script>

Why is this not appearing in my browser(Firefox)?

Answer 1

Add Imports System.Web.Script.Serialization to the top of your file, then try this:

Private Sub MesgBox(ByVal sMessage As String)
    Dim serializer as New JavaScriptSerializer()
    Dim msgedtble As String = serializer.Serialize(sMessage)
    Page.ClientScript.RegisterStartupScript(Me.GetType, "myScripts",
        "<script type='text/javascript'>alert(" & msgedtble & ");</script>")
End Sub

Using JavaScriptSerializer should take care of the linebreaks, single quotes, and everything else we haven’t already thought of.