In a FormView, how to change the property of a Label in the ItemTemplate

asp.netdata-binding

In ASP.NET, I have a FormView which is bound to an ObjectDataSource. The FormView has an ItemTemplate with a Delete button, and a Label. I'm handling the OnItemDeleted event of the FormView to detect if my business class throws an exception upon deletion. If an exception is detected, I change the text of the Label to whatever the exception message is.

Well, it's just not working.

I detect the Exception fine, but the Text of the Label never gets changed. When the page reloads, the default text stays. I have also tried to rebind the FormView with DataBind() after assigning the new Text, but it's not working either.

In a desperate attempt at tracking the problem, I've taken the Label out of the FormView and it's working fine.

What I am doing wrong?

ASPX page:

<asp:ObjectDataSource ID="MyObjectDataSource" 
    TypeName="MyScopeRepository" 
    SelectMethod="GetById"
    DeleteMethod="Delete"
    runat="server">

    <SelectParameters>
        <%-- The id param here is from a DropDownList, not included in the example for clarity. --%>
        <asp:ControlParameter Name="id" Type="Int32" ControlID="MyDropDownList" PropertyName="SelectedValue" />
    </SelectParameters>
    <DeleteParameters>
        <asp:Parameter Name="id" Type="Int32" />
    </DeleteParameters>
</asp:ObjectDataSource>

<asp:FormView ID="MyFormView" DataSourceID="MyObjectDataSource"
    RenderOuterTable="false"
    DataKeyNames="Id"
    OnItemDeleted="MyFormViewItemDeleted"
    runat="server">

    <ItemTemplate>
        <asp:Button CssClass="Button Small" Text="Delete" CommandName="Delete" runat="server" /><br />
        <asp:Label ID="ErrorLabel" Text="Default text" runat="server" />
    </ItemTemplate>
</asp:FormView>

Code-behind:

protected void MyFormViewItemDeleted(object sender, FormViewDeletedEventArgs e)
{
    if (e.Exception != null && e.Exception.InnerException is RepositoryException)
    {
        Label errorLabel = (Label)MyFormView.FindControl("ErrorLabel");
        errorLabel.Text = e.Exception.InnerException.Message;
        e.ExceptionHandled = true;

        // I also tried this to no avail.
        //MyFormView.DataBind();
    }
}

Thanks a lot!

EDIT: I've checked all events fired by the FormView when clicking the Delete button and here is what I got:

  1. OnInit
  2. OnItemCreated
  3. OnLoad
  4. OnItemCommand
  5. OnItemDeleting
  6. OnItemDeleted
  7. OnItemCreated
  8. OnDataBound
  9. OnPreRender
  10. OnUnload

So we can see that OnItemCreated gets fired twice, and the second time it's fired is AFTER OnItemDeleted, which means that whatever change I make is overwritten, I suppose. Now how am I supposed to handle that?

Best Solution

Here is working solution (You may want to improve it):

<asp:FormView ID="FormView1" runat="server" DataSourceID="ObjectDataSource1" 
    AllowPaging="true" OnItemDeleted="FormView1_ItemDeleted" ondatabound="FormView1_DataBound" >
    <ItemTemplate>
        Key:
        <asp:Label ID="KeyLabel" runat="server" Text='<%# Bind("Key") %>' />
        <br />
        Value:
        <asp:Label ID="ValueLabel" runat="server" Text='<%# Bind("Value") %>' />
        <br />
        <asp:Button ID="DeleteButton" runat="server" CausesValidation="False" CommandName="Delete"
            Text="Delete" />
        <hr />
        <asp:Label ID="Label1" runat="server" Text="does not work"></asp:Label>
    </ItemTemplate>
</asp:FormView>
<asp:ObjectDataSource ID="ObjectDataSource1" runat="server" SelectMethod="GetList"
    DeleteMethod="Delete" TypeName="MyProject.Repository">
    <DeleteParameters>
        <asp:Parameter Name="key" Type="Int32" />
    </DeleteParameters>
</asp:ObjectDataSource>

codebehind:

public string MyProperty { get; set; }
        protected void FormView1_DataBound(object sender, EventArgs e)
        {
            if (!string.IsNullOrEmpty(MyProperty))
            {
                Label l = FormView1.FindControl("Label1") as Label;
                l.Text = "it works. " + MyProperty;
                MyProperty = null;
            }
        }

        protected void FormView1_ItemDeleted(object sender, FormViewDeletedEventArgs e)
        {
            if (e.Exception != null)
            {
                MyProperty = e.Exception.Message;
                e.ExceptionHandled = true;
            }
        }
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