CODEWITHSUNDEEP
vb.netsql-server-2008
BLitE.exe
BLitE.exe

Reputation: 321

Cant retrieve Image from SQL Server In Vb.net

i have a database that has field name of the following and also within the same table it also a field name "photo" and has a data type Varbinary(max)

i have no trouble in storing images but when i tried to display the image file from my database it doesnt display anything and i get an error "Unable to cast object of type 'System.String' to type 'System.Byte[]'."

Sub fillDataFields()
    Dim mid As String
    Dim last As String
    Dim first As String
    con.Open()
    comm.CommandText = "Select last_name,middle_name,first_name,course, section, address, birthday, picture from Users where user_id like '%" & frmUsers.ListView1.SelectedItems(0).Text & "%'"
    comm.Connection = con
    Dim imageData As Byte() = DirectCast(comm.ExecuteScalar(), Byte())
    If Not imageData Is Nothing Then
        Using ms As New MemoryStream(imageData, 0, imageData.Length)
            ms.Write(imageData, 0, imageData.Length)
            PictureBox1.BackgroundImage = Image.FromStream(ms, True)
        End Using
    End If
    dr = comm.ExecuteReader
    While (dr.Read())
        last = (dr("last_name"))
        mid = (dr("middle_name"))
        first = (dr("first_name"))
        txtCourse.Text = (dr("course"))
        txtSection.Text = (dr("section"))
        richtxtAddress.Text = (dr("address"))
        txtBirthday.Text = (dr("birthday"))
        txtName.Text = last + ", " + first + " " + mid
    End While

    con.Close()
    dr.Close()
    comm.Dispose()
End Sub

Upvotes: 0

Views: 1831

Answers (1)

Steve
Steve

Reputation: 216348

You try to extract the image data using ExecuteScalar, but this method returns the first column of the first row and, in your query, this data is the content of the field Last_Name. This is the cause of the error

Said that, I suppose that you should apply your logic to the content of the field Picture 

Sub fillDataFields()
    Dim mid As String
    Dim last As String
    Dim first As String

    con.Open()
    comm.CommandText = "Select last_name,middle_name,first_name,course, section, address, " & _
                       "birthday, picture from Users where user_id like @uid"
    comm.Connection = con
    comm.Parameters.AddWithValue("@uid", "%" & frmUsers.ListView1.SelectedItems(0).Text & "%")
    dr = comm.ExecuteReader
    While (dr.Read())
        last = (dr("last_name"))
        mid = (dr("middle_name"))
        first = (dr("first_name"))
        txtCourse.Text = (dr("course"))
        txtSection.Text = (dr("section"))
        richtxtAddress.Text = (dr("address"))
        txtBirthday.Text = (dr("birthday"))
        txtName.Text = last + ", " + first + " " + mid

        Dim imageData As Byte() = DirectCast(dr("picture"), Byte())
        If Not imageData Is Nothing Then
            Using ms As New MemoryStream(imageData, 0, imageData.Length)
               ms.Write(imageData, 0, imageData.Length)
               PictureBox1.BackgroundImage = Image.FromStream(ms, True)
           End Using
        End If
    End While
    con.Close()
    dr.Close()
    comm.Dispose()
End Sub

Notice that I have also removed the string concatenation because it is a security rìsk (Sql Injection). You should also revise this code to apply the required logic for the using statement

Upvotes: 3

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