Displaying different pictures in GridView depending on the data?

Question

I am creating a WEB report in Visual Studio 2010 in VB.net. The report needs to display a table (please see the attached image). I am thinking to use the GridView component which i think it's the most appropriate one to choose. In the database there are students' data and marks. I can't alter the database in any way and i have to use Visual Studio 2010 with VB.

What i need to do is to show 3 different pictures(for example) depend on the student's marks. I got the pictures file in PNGs but this can be flexible.For example, over 70 will be a Smile picture. over 60 will be the Normal face. and over 40 will be the picture with no smile. I bit difficult for me to explain but i hope u get my point.

So pls advice me how can i achieve this. I am quite a newbie to this pls put as detail as you can. if there is a choice between client and server side script, i prefer server side script. Data source can be flexible (sql, or linq or anything).

Answer 1

You should use RowDataBound to bind data to controls in your GridView.

Following is a complete sample with aspx and codebehind(says more than thousand words):

<style type="text/css">
    .GridViewRowStyle
    {
        background-color: #A0CFEC;
        color:Blue;
    }
    .GridViewAlternatingRowStyle
    {
        background-color:White;
        color:#15317E;
    }
    .GridViewHeaderStyle
    {
        background-color:White;
        color:#15317E;
    }
</style>

<asp:GridView ID="GridStudents" AutoGenerateColumns="false" GridLines="None" runat="server">
    <RowStyle  CssClass="GridViewRowStyle" />
    <AlternatingRowStyle CssClass="GridViewAlternatingRowStyle" />
    <HeaderStyle CssClass="GridViewHeaderStyle" />
    <Columns>
        <asp:TemplateField HeaderText="Student">
           <ItemTemplate>
                <asp:label runat="server" ID="LblStudent" Text='<%# Bind("Student") %>'></asp:label>
            </ItemTemplate>
        </asp:TemplateField>
         <asp:TemplateField HeaderText="Mark">
           <ItemTemplate>
                <asp:label runat="server" ID="LblMark" Text='<%# Bind("Mark") %>'></asp:label>
            </ItemTemplate>
        </asp:TemplateField>
        <asp:TemplateField HeaderText="">
           <ItemTemplate>
                <asp:Image runat="server" ID="ImgSmiley" />
            </ItemTemplate>
        </asp:TemplateField>
    </Columns>
</asp:GridView>

Codebehind(with sample-data):

Private Sub GridStudents_RowDataBound(sender As Object, e As System.Web.UI.WebControls.GridViewRowEventArgs) Handles GridStudents.RowDataBound
    Select Case e.Row.RowType
        Case DataControlRowType.DataRow
            Dim row = DirectCast(e.Row.DataItem, DataRowView)
            Dim ImgSmiley = DirectCast(e.Row.FindControl("ImgSmiley"), Image)
            Select Case DirectCast(row("Mark"), Int32)
                Case Is < 50
                    ImgSmiley.ImageUrl = "~/Images/Smiley_Grim.png"
                    ImgSmiley.ToolTip = "bad"
                Case Is < 70
                    ImgSmiley.ImageUrl = "~/Images/Smiley_Def.png"
                    ImgSmiley.ToolTip = "ok"
                Case Else
                    ImgSmiley.ImageUrl = "~/Images/Smiley_Laugh.png"
                    ImgSmiley.ToolTip = "fine"
            End Select
    End Select
End Sub

Protected Sub Page_Load(ByVal sender As Object, ByVal e As System.EventArgs) Handles Me.Load
    If Not IsPostBack Then
        BindData()
    End If
End Sub

Private Sub BindData()
    Dim tblStudent As New DataTable("Students")
    Dim colStudent = New DataColumn("Student", GetType(String))
    Dim colMark As New DataColumn("Mark", GetType(Int32))
    tblStudent.Columns.Add(colStudent)
    tblStudent.Columns.Add(colMark)

    Dim newRow = tblStudent.NewRow
    newRow("Student") = "Tom"
    newRow("Mark") = 70
    tblStudent.Rows.Add(newRow)
    newRow = tblStudent.NewRow
    newRow("Student") = "Bob"
    newRow("Mark") = 40
    tblStudent.Rows.Add(newRow)
    newRow = tblStudent.NewRow
    newRow("Student") = "Danny"
    newRow("Mark") = 60
    tblStudent.Rows.Add(newRow)
    newRow = tblStudent.NewRow
    newRow("Student") = "Sussie"
    newRow("Mark") = 40
    tblStudent.Rows.Add(newRow)

    GridStudents.DataSource = tblStudent
    GridStudents.DataBind()
End Sub