Hi there.

I have a question I have wanted to ask for a while now...

I have a Repeater with 2 DropDownLists. 1 is for a List of Expressions. 1 is for a List of Rules.

They are both bound to 2 different ObjectDataSource's. Basically as the Repeater iterates I want to display 1 or the other.

The problem is both are always bound, even when I make them visible or not.

Is there a good way to do this or is the Repeater the wrong Control to be using?

Here is the code I am using:

<table border="0" cellpadding="3">
   <asp:Repeater ID="rptExpressions" runat="server" DataSourceID="AddExpressionList" EnableViewState="true" >
      <ItemTemplate>
      <asp:Panel ID="panExpression" runat="server" Visible='<%# Eval("ExpressionType").ToString() == "Expression" %>'>
         <tr>
            <td>
               <asp:LinkButton ID="butRemove" runat="server" Text="Remove" OnClick="RemoveExpression_Click" CommandArgument='<%# Container.ItemIndex %>' />
            </td>
            <td>
               <asp:DropDownList ID="drpVariableList" runat="server" AutoPostBack="true"
                  DataSourceID="VariableList" DataTextField="Name" 
                  OnSelectedIndexChanged="VariableChanged_Selected" OnDataBound="Variable_Created" 
                  Text='<%# Eval("SelectedVariable") %>' Width="200" />
            </td>
            <td>
               <asp:DropDownList ID="drpOperatorList" runat="server" Width="140" />
            </td>
            <td>
               <asp:TextBox ID="txtValue" runat="server" Text='<%# Eval("SelectedValue") %>' />
            </td>
         </tr>
      </asp:Panel>

      <asp:Panel ID="panRules" runat="server" Visible='<%# Eval("ExpressionType").ToString() == "Rule" %>'>
         <tr>
            <td>
               <asp:LinkButton ID="LinkButton1" runat="server" Text="Remove" OnClick="RemoveExpression_Click" CommandArgument='<%# Container.ItemIndex %>' />
            </td>
            <td>
               <asp:DropDownList ID="drpRuleList" runat="server" OnDataBound="Rule_Created"
                  DataSourceID="RuleList" DataTextField="Name" 
                  Width="200" />
            </td>
            <td>
               <asp:DropDownList ID="drpRuleValue" runat="server" Width="140">
                  <asp:ListItem Text="True" />
                  <asp:ListItem Text="False" />
               </asp:DropDownList>
            </td>
            <td>
            </td>
         </tr>
      </asp:Panel>      
                                       
      </ItemTemplate>
   </asp:Repeater>
</table>

 

Hi,

What I am understand from your post is that controls in Repeater are always doing databinding

I think this behavior is apply to all Data Controls

If you want to minize the databinding, you may do manual databinding
E.g.

    Protected Sub GridView1_RowDataBound(ByVal sender As Object, ByVal e As System.Web.UI.WebControls.GridViewRowEventArgs) Handles GridView1.RowDataBound
        If e.Row.RowType = DataControlRowType.DataRow Then
            Dim ddl As DropDownList = e.Row.FindControl("DropDownList1")

            If e.Row.DataItem("FirstName").ToString.StartsWith("I") Then
                If Not ddl Is Nothing Then
                    With ddl
                        .DataTextField = "DepartmentGroupName"
                        .DataValueField = "DepartmentGroupKey"
                        .DataSourceID = "departmentDS"
                    End With
                End If
            Else
                ddl.Visible = False
            End If
        End If
    End Sub

And removed properties on HTML

<asp:DropDownList ID="DropDownList1" runat="server"/>

Hope it help

IF the data were always either one or the other of "Expression" OR "Rule" then you could have thought of using dynamic templates (example: http://www.devx.com/vb2themax/Article/19908) ....but otherwise what you're doing is good enough.

to reduce the overhead of binding you can choose to bind manually..in your case it will be the ItemDataBound event ...and don't forget to remove the DataSourceID assigned by default in the markup

Odd that Visible seems to bind after the contents of the Panel are bound.
You might want to try handing the DataBinding event of the Panels. The NamingContainer of the sender object will be the Item that is being bound. That will have a DataItem that you can use to set Visible.
However, I am not sure this will work, as it may be too late by then to stop the DataBinding process.

http://www.devx.com/vb2themax/Article/19908)

Interesting idea but my data is a mixture of the Expressions and Rules so that wouldn't work.

I guess though this has answered by question.

Everything thats bindable in an ItemTemplate is always bound, regardless of if it is visible.

Basically now I only bind to the 'value' control if it is an Expression or Rule by checking in the code behind after the DataBound event.

<asp:DropDownList ID="drpExpressionList" runat="server" 
   DataSourceID="VariableList" DataTextField="Name" OnDataBound="Expression_Created"

<asp:DropDownList ID="drpRuleList" runat="server" 
   DataSourceID="RuleList" DataTextField="Name" OnDataBound="Rule_Created"

 protected void Rule_Created(object sender, EventArgs e)
    {
    RuleManagement.State state = State.Applications<State.RuleManagement.State>.State;
    AddExpressionItem item = state.AddExpressionList[rptExpressions.Controls.Count - 1];

    if (item.ExpressionTypeEnum == ExpressionType.Rule)
        // Bind Value Control etc...

I have to disagree that everything is always DataBound. I have seen GridViews not DataBinding when in Panels that have Visible=false. However, that was for Panels that didn't DataBind Visible. I guess it is a matter of timing. If you set Visible=false in time, what is in it will not be DataBound.