ErrorLog and File Handling

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Introduction

In this article files have been directly pushed into the database as "images." At the same time there is also provision for downloading. To keep the file in a database is much more secure than to keeping it in a local drive. Also, logging the error in a particular file and writing it in a text file has been done.

Using the Code

SQLExpress 2005 has been used for storing the file data,size and content type. For error handling (i.e Error Log) a class file has been used.

--For Uploading and Downloading the file--

    Protected Sub btnAttach_Click(ByVal sender As Object,
            ByVal e As System.EventArgs) Handles btnAttach.Click
        Dim iLength As Integer = CType(File1.PostedFile.InputStream.Length, Integer)
        If iLength = 0 Then Exit Sub 'not a valid file 
        Dim sContentType As String = File1.PostedFile.ContentType
        Dim sFileName As String, i As Integer
        Dim bytContent As Byte()
        ReDim bytContent(iLength) 'byte array, set to file size 

        'strip the path off the filename 
        i = InStrRev(File1.PostedFile.FileName.Trim, "\")
        If i = 0 Then
            sFileName = File1.PostedFile.FileName.Trim
        Else
            sFileName = Right(File1.PostedFile.FileName.Trim,
            Len(File1.PostedFile.FileName.Trim) - i)
        End If

        Try
            File1.PostedFile.InputStream.Read(bytContent, 0, iLength)
            
            Dim dbConn As SqlConnection = New SqlConnection(
                ConfigurationManager.ConnectionStrings("ConnectionString").ToString())
            Dim str As String
            str = "select * from tblAttachments where attachmentID=1"


            Dim cmd As SqlCommand = New SqlCommand(str, dbConn)
            dbConn.Open()
            Dim da As SqlDataAdapter = New SqlDataAdapter(cmd)
            Dim ds As DataSet = New DataSet()
            Dim cb As New SqlCommandBuilder(da)

            da.Fill(ds, "tblAttachments")
            Dim myRow As DataRow
            myRow = ds.Tables("tblAttachments").NewRow()

            myRow("FileName") = sFileName
            myRow("FileSize") = iLength.ToString()
            myRow("FileData") = bytContent
            myRow("ContentType") = sContentType

            ds.Tables("tblAttachments").Rows.Add(myRow)
            da.Update(ds, "tblAttachments")

            dbConn.Close()
            Dim int1 As Integer = 10
            Dim int2 As Integer = 0
            Dim intResult As Integer

           
            intResult = int1 / int2

        Catch ex As Exception
            Response.Write(ex.Message)
            Dim el As New ErrorLogger
            el.WriteToErrorLog(ex.Message, ex.StackTrace, "Error")

            MsgBox("File Upload Successfully and Error logged in C:\Errors.")
            'Handle your database error here 
            '  dbnConn.Close()
        End Try
    End Sub
    

 Protected Sub btnDownload_Click(ByVal sender As Object,
     ByVal e As System.EventArgs) Handles btnDownload.Click


        
        Try
            
            Dim dbConn As SqlConnection = New SqlConnection(
                ConfigurationManager.ConnectionStrings("ConnectionString").ToString())
            Dim dr As System.Data.SqlClient.SqlDataReader
            Dim str As String
            str = "select * from tblAttachments where attachmentID=19"
            Dim cmd As SqlCommand = New SqlCommand(str, dbConn)
            dbConn.Open()
            dr = cmd.ExecuteReader
            If dr.Read Then
                Response.Clear()
                Response.Buffer = True
                Response.ContentType = dr("ContentType").ToString
                Response.AddHeader("Content-Disposition", "attachment;filename=" +
                    dr("FileName").ToString())
                Response.Buffer = True
                Response.BinaryWrite(CType(dr("FileData"), Byte()))

            Else
                Response.Write("File Not Found.")
            End If

            dbConn.Close()


        Catch ex As Exception
            'Handle your database error here 
            '  dbnConn.Close()
        End Try
    End Sub
End Class