ObjectDataSource reacts to commented-out GridView?

Question

I came across a very strange behavior in asp.net's ObjectDataSource, the description to reproduce is somewhat long, so bear with me while I set the scene.

So, imagine a trivial ObjectDataSource/GridView combo in a User Control. The ObjectDataSource calls a method which returns a List of objects, and the GridView shows these objects in tabular form:

<div runat="server" ID="ControlWrapper">
    <asp:GridView ID="GridView1" AutoGenerateColumns="true" DataSourceID="ObjDataSource1" OnRowDataBound="GridView1_RowBound" runat="server">
    </asp:GridView>

</div>

<asp:ObjectDataSource ID="ObjDataSource1" runat="server" SelectMethod="GetBundle" OnSelecting="FixDataSource_Selecting"  OnSelected="FixDataSource_Selected"
    TypeName="West.VitalSigns.Contracts.ProdFixController">
</asp:ObjectDataSource>

This approach will work with pretty much nothing in the code-behind. But let's say that we want to create n number of GridView-s depending on the contents of the database. So we comment out the GridView in the markup...

<div runat="server" ID="ControlWrapper">
<!--
<asp:GridView ID="GridView1" AutoGenerateColumns="true" DataSourceID="ObjDataSource1" OnRowDataBound="GridView1_RowBound" runat="server">
    </asp:GridView>
-->
</div>

...and add something like this to the ObjectDataSource's Selected event handler:

protected void FixDataSource_Selected(object sender, ObjectDataSourceStatusEventArgs args)
    {
     HashSet<string> components = new HashSet<string<()
        foreach (ProdFix fix in (List<ProdFix>)args.ReturnValue)
        {
            if (!components.Contains(fix.Component))
            {
                GridView v = new GridView();
                v.ID=fix.Component.Replace(" " ,"").Replace("-","");
                v.AutoGenerateColumns = true;
                v.DataSource = args.ReturnValue;
                v.RowDataBound +=new GridViewRowEventHandler(BundleGrid_RowBound);
                ControlWrapper.Controls.Add(v);
       components.Add(fix.Component);

            }
        }
    }

This code works (or at least the un-simplified version works on my machine), so you decide to remove the commented-out section from the markup (don't want that cruft hanging around, after all!)

<div runat="server" ID="ControlWrapper">

</div>

When you do this, however, the code no longer works! The ObjectDataSource won't fire, which means that the Selected event will never happen, which means you won't get your GridView-s. It looks like ObjectDataSource is reacting to commented-out markup in the aspx file?

So, is this:

• A bug in ASP.NET?
• A non-standard way of dynamically creating GridViews?
• A WTF that I shouldn't have tried anyway?
• All of the above?

Answer 1

Your gridview control in the markup is not hidden, even with the comments. HTML comments do not apply to server-side tags. Use server side comments instead:

<% /* %>     <% */ %>

or

<%-– and -–%>

Answer 2

24hrs later, I noticed that this approach to getting N number of grid-views was pretty silly. Instead of using an ObjectDataSource I refactored my code to just call the GetBundle method directly from Page_Load() and create the GridViews programatically.

cdonner has the answer correct about the server-side comments. I didn't realize that there was a difference.

Answer 3

This should work too, since you're "disabling" the tag with it:

<!--asp:GridView ID="GridView1" AutoGenerateColumns="true" DataSourceID="ObjDataSource1" OnRowDataBound="GridView1_RowBound" runat="server">
    </asp:GridView-->