Using IF ELSEIF and ELSE Condition with EVAL function in ASP.Net using C#

I'am using ASP.NET C#, and I have to do something like this:

   <asp:TemplateField
        HeaderText="text"
        ItemStyle-HorizontalAlign="Center"
        ItemStyle-CssClass="ddl_Class_new">
        <ItemTemplate>
            <% if (Eval("dOR_4").ToString().Equals("R"))
                { %>
            <asp:ImageButton ID="btn"
                ImageUrl="/Img/bullett/redbul.gif"
                runat="server" />
            <% }
            else if (Eval("dOR_4").ToString().Equals("G"))
            { %>
            <asp:ImageButton ID="btn"
                ImageUrl="/Img/bullett/goldbul.gif"
                runat="server" />
            <% }
            else if (Eval("dOR_4").ToString().Equals("V"))
            { %>
            <asp:ImageButton ID="btn"
                ImageUrl="/Img/bullett/forestbul.gif"
                runat="server" />
            <% } %>
        </ItemTemplate>
    </asp:TemplateField>

But I'am getting error "Databinding methods such as Eval(), XPath(), and Bind() can only be used in the context of a databound control."

I have tried using my code below, but I don't see the goldbul.gif

<asp:TemplateField
    HeaderText="text"
    ItemStyle-HorizontalAlign="Center"
    ItemStyle-CssClass="ddl_Class_new">
    <ItemTemplate>
        <asp:ImageButton ID="btn"
            ImageUrl='<%# Eval("dOR_4").ToString().Equals("R") ? 
                           "/Img/bullett/redbul.gif" :
                          Eval("dOR_4).ToString().Equals("G") ? 
                           "/Img/bullett/goldbul.gif" : "/Img/bullett/forestbul.gif" %>'
            runat="server" />
    </ItemTemplate>
</asp:TemplateField>

Any help really appreciated

by making use of IF ELSEIF ELSE condition with EVAL function

Actually, don't try and write or include that code in the page markup. It is a mess, and worse will make your life miserable anyway.

Since the grid view is a server side control, then you have "many" options to write a bit of clean code to deal with your example use case.

Be it a gridview, listview, repeater, or many of the other data bound controls?

They all have a row data bound event. So, that event is not only simple, but is your "go to" bit of code for things like formatting, hide/show controls, or even doing things like highlights, color.

And EVEN better?

That event has the FULL database row during that binding event. In other words, for columns that you don't even "display" or include in the gridview? You can STILL use those columns! So, you might have a tax calulation, but don't need or want to show the tax rate.

Or maybe even a simple list of hotels, and you have a boolean "active" column, and for any active hotel, you might color that row of data "light blue" or some such. (but, again the real bonus points is that Active column does NOT have to appear in the markup!!!).

So, for such goals here, use the row data bound event. You find it not only has a million use cases, but also means you don't require have messy markup intermixed with some code.

So, for your case?

Then I suggest the row data bound event.

so, say this markup:

<asp:GridView ID="GridView1" runat="server" AutoGenerateColumns="False"
    DataKeyNames="ID" CssClass="table table-hover" width="45%"
    OnRowDataBound="GridView1_RowDataBound">
    <Columns>
        <asp:BoundField DataField="FirstName" HeaderText="FirstName" />
        <asp:BoundField DataField="LastName" HeaderText="LastName" />
        <asp:BoundField DataField="City" HeaderText="City" />
        <asp:BoundField DataField="HotelName" HeaderText="HotelName" ItemStyle-Width="120px" />
        <asp:BoundField DataField="Description" HeaderText="Description" />

        <asp:TemplateField HeaderText="Status" ItemStyle-HorizontalAlign="Center">
            <ItemTemplate>
                <asp:ImageButton ID="ImageButton1" runat="server" Width="64"
                    OnClick="ImageButton1_Click" />
            </ItemTemplate>
        </asp:TemplateField>
    </Columns>
</asp:GridView>

So, we have a image button.

I have a PassedTest column (value 2 = good, 1 = bad, 0 = no status).

So, I have this code in the row data bound event:

protected void GridView1_RowDataBound(object sender, GridViewRowEventArgs e)
{
    if (e.Row.RowType== DataControlRowType.DataRow)
    {
        ImageButton Ibtn = (ImageButton)e.Row.FindControl("ImageButton1");

        DataRowView rData = (DataRowView)e.Row.DataItem;

        // passed test (room been cleaned) 2 = yes, 1, rejected, 0 - no status

        switch ((int)rData["PassedTest"])
        {
            case 2:
                Ibtn.ImageUrl = ResolveUrl(@"~/Content/Approved80.png");
                break;
            case 1:
                Ibtn.ImageUrl = ResolveUrl(@"~/Content/Reject80.png");
                break;

            default:
                Ibtn.ImageUrl = ResolveUrl(@"~/Content/Empty80.png");
                break;
        }

    }
}

So, code to load is this:

    protected void Page_Load(object sender, EventArgs e)
    {
        if (!IsPostBack)
            LoadGrid();
    }

    void LoadGrid()
    {
        string strSQL =
            "SELECT * FROM tblHotelsA ORDER BY HotelName";
        GridView1.DataSource = General.MyRst(strSQL);
        GridView1.DataBind();

    }

And the result is now this:

So, you don't have messy markup.

You don't have to intermix code and markup.

You have a clean nice row event to use

The row event has full database/data source row.

and you keep all the code in code behind for that page.