CODEWITHSUNDEEP
asp.net.netdata-bindingeval
Bryan
Bryan

Reputation: 8788

How to call Eval in codebehind?

How the heck do I call Eval() from codebehind? I know this is a front-end shortcut for something like DataBinder.Eval(Container.DataItem, "name"), but I cannot get this damn thing to compile. I am missing the proper method parameters, I think. I want to turn something like this:

<asp:Image ID="imgLogo" runat="server" ImageUrl='<%# Eval("name") %>'/>

into:

<asp:Image ID="imgLogo" runat="server" ImageUrl='<%# GetImagePath(???) %>'/>

w/ code-behind:

protected string GetImagePath(????)
{
    //some code
    return "some/logical/path" + Eval("name");
}

The asp:Image control is in a repeater that is bound to a SqlDataReader.

Upvotes: 18

Views: 28620

Answers (5)

Jeson Martajaya
Jeson Martajaya

Reputation: 7352

Ruben's answer works, but in case you need to include some argument for ???? and want to avoid calling Eval, here is the more complete answer.

<asp:Image ID="imgLogo" runat="server" ImageUrl='<%# GetImagePath("SomeData") %>'/>

And code behind:

protected string GetImagePath(string someDataHere)
{
    object dataItem = null;
    try
    {
        dataItem = Page.GetDataItem();
    }
    catch (InvalidOperationException ex) // Thrown when the control is not data bound
    {
        return null;
    }

    string name = DataBinder.Eval(dataItem, "name").ToString();
    return "some/logical/path/" + someDataHere + "/" + name;
}

Upvotes: 0

Nigel Sampson
Nigel Sampson

Reputation: 10609

Another simple way to do this is to use the overload of Eval that takes a format, the aspx becomes:

<asp:Image ID="imgLogo" runat="server" ImageUrl='<%# Eval("name", "some/logical/path/{0}") %>'/>

Upvotes: 2

tvanfosson
tvanfosson

Reputation: 532745

Have you tried something like:

<asp:Image ID="imgLogo" runat="server' ImageUrl='<%# GetImagePath( Convert.ToString( Eval("name") ) ) %>' />

and

protected string GetImagePath( string image )
{
    return "some/logical/path/" + image;
}

Upvotes: 5

Ruben
Ruben

Reputation: 15555

Eval is a method on Page (on TemplateControl actually, which means that it's also present on UserControl). So you don't need to pass any special parameters:

protected string GetImagePath()
{
    //some code
    return "some/logical/path" + Eval("name");
}

Caution: you can only call Eval while databinding, but that's implicitly the case for <%# Eval(...) %> too, so that shouldn't pose a problem.

If you want the actual object you're binding to, use GetDataItem(), as Eval(x) basically means DataBinder.Eval(GetDataItem(), x).

Upvotes: 17

John Sheehan
John Sheehan

Reputation: 78152

protected void rProducts_ItemDataBound(object sender, RepeaterItemEventArgs e) {
    if (e.Item.ItemType == ListItemType.AlternatingItem || e.Item.ItemType == ListItemType.Item) {

        Image ProductImage = (Image)e.Item.FindControl("ProductImage");
        ProductImage.ImageUrl = DataBinder.Eval(e.Item.DataItem, "ProductImageUrl");

        // Or strongly typed
        Product product = (Product)e.Item.DataItem;
        ProductImage.ImageUrl = product.ProductImageUrl;
    }
}

Upvotes: 4

Related Questions