You must Sign In to post a response.
  • Category: Visual Studio

    Winforms N-Tier - Retrieve and display image from sql server database

    Am new to N-Tier programming and in the process of learning more, I want to retrieve an image from SQL Server database using N-tier architecture. I have managed to save the image but am facing issues in getting the image from the database, passing it as a parameter and then displaying the image.

    Data Access Layer Code:

    Public Function SelectRecord(ByVal clsdbo_ProductsPara As AppName.BusinessLogic.BLL_Products) As AppName.BusinessLogic.BLL_Products
    Dim clsDAL_Products As New AppName.BusinessLogic.BLL_Products
    Dim connTemp As SqlConnection = AppName.DataAccess.AppNameDataClass.GetConnection
    Dim strSelect As String = "SELECT * FROM [dbo].[Products] WHERE [ProductID] = @ProductID"
    Dim cmdSelect As New SqlCommand(strSelect, connTemp)
    cmdSelect.CommandType = CommandType.Text
    cmdSelect.Parameters.AddWithValue("@ProductID", clsdbo_ProductsPara.ProductID)
    Dim rdrTemp As SqlDataReader = strCommandSelect.ExecuteReader(CommandBehavior.SingleRow)
    If rdrTemp.Read Then
    With clsdbo_ProductsPara
    .ProductID = System.Convert.ToString(rdrTemp("ProductID"))
    .ProductDesc = If(IsDBNull(rdrTemp("ProductDesc")), Nothing, rdrTemp("ProductDesc"))
    .ProductImage = If(IsDBNull(rdrTemp("ProductImage")), Nothing, rdrTemp("ProductImage"))
    End With
    clsdbo_ProductsPara = Nothing
    End If
    Catch ex As SqlException
    MsgBox(ex.Message, MsgBoxStyle.Critical, "Error")
    End Try
    Return clsdbo_ProductsPara
    End Function

    Presentation Layer Code:

    Private Sub DisplaySelectedRecordDetails()
    Dim clsdbo_ProductsPara As New AppName.BusinessLogic.BLL_Products
    clsdbo_ProductsPara.ProductID = System.Convert.ToString(lblProductID.Text)
    clsdbo_ProductsPara = clsdbo_ProductsData.SelectRecord(clsdbo_ProductsPara)
    If Not clsdbo_ProductsPara Is Nothing Then
    txtProductDesc.Text = Convert.ToString(clsdbo_ProductsPara.ProductDesc)
    picProductImage.Image = Nothing
    If Not IsDBNull(clsdbo_ProductsPara.ProductImage) Then
    Dim data As Byte = Convert.ToByte(clsdbo_ProductsPara.ProductImage.GetType)
    Dim bw As New BinaryWriter(New MemoryStream)
    Dim img As Image = Image.FromStream(bw.BaseStream, True)
    Me.picProductImage.Image = img
    End If
    End Try
    End If
    End Sub

    First, I had like to know what is the correct way of retrieving the image using this method. Secondly I am getting conversion errors Conversion from type 'Byte()' to type 'Byte' is not valid. in the DAL block on the line .ProductImage = If(IsDBNull(rdrTemp("ProductImage")), Nothing, rdrTemp("ProductImage"))

    Please help correct the above for me to understand.


  • #747064

    Since you are getting byte array you should use the same to fetch the value. So your array declaration will be something like below,

    Dim data As Byte() = {}
    data = Convert.ToByte(clsdbo_ProductsPara.ProductImage.GetType)

    Try to change it like this and see if you are still getting any exception or not.

    Asheej T K

  • #747066
    Hi Asheej,

    Thanks for the response but making the change did not help. I am getting this error now -
    Value of type 'Byte' cannot be converted to '1-dimensional array of Byte'
    on the same line. I tried with both image and varbinary(MAX) as the datatype.

  • Sign In to post your comments