Question

The web user control: FilterLabel

<span style=" display:block; float:left; margin:5px; padding: 5px; border: 1px inset #000000; font-family: Tahoma; font-size: small;">
<asp:Label ID="lblFilterDisplay" runat="server" Text="Product/Service: This is a testing"></asp:Label>
&nbsp;
<asp:ImageButton ID="btnRemove" runat="server" ImageUrl="~/Images/remove.png" OnClick="btnRemove_Click" />

And the part of behind codes for this web user control:

public event EventHandler RemoveClick;
......
public void btnRemove_Click(object sender, EventArgs e)
{
    if (RemoveClick != null)
        RemoveClick(this, EventArgs.Empty);
}

Next, the web user control “FilterLabel” will be used in another web user control “FilterList”:

<%@ Register TagPrefix="uc" TagName="FilterLabel" Src="~/Controls/FilterLabel.ascx" %>
<asp:Panel ID="FilterList" runat="server" Width="100%" GroupingText="Filter List" CssClass="filterList">
</asp:Panel>

And the part of behind codes of this web user control is:

protected override void OnInit(EventArgs e)
{
    if (IsPostBack)
    {
        BindFilters();
    }

}

public void BindFilters()
{
    List<FilterLabel> filters = Filters;
    foreach (FilterLabel filter in filters)
    {
        FilterList.Controls.Add(filter);
    }
}

public List<FilterLabel> Filters
{
    get
    {
        List<FilterLabel> filters = Session["Filters"] as List<FilterLabel>;
        if (filters == null)
        {
            filters = new List<FilterLabel>();
        }
        return filters;
    }
}

public void AddFilter(string filterName, string filterContent, string filterValue = null)
{
    FilterLabel filter = LoadControl("~/Controls/FilterLabel.ascx") as FilterLabel;
    filter.ID = "Filter";
    filter.FilterContent = filterContent;
    filter.FilterName = filterName;
    filter.Value = filterValue;
    filter.RemoveClick += new EventHandler(RemoveFilter);
    List<FilterLabel> filters = Filters;
    filters.Add(filter);
    Session["Filters"] = filters;
    BindFilters();
}

private void RemoveFilter(object sender, EventArgs e)
{
    //some handling codes
}

So now the problem is the btnRemove_Click event isn’t activated when I click the image button “btnRemove”.

Answer 1

You should try with bubble event. with your solution you will need on each postback to rebind event handler on each usercontrol for existing filters

public int FilterCount 
{
    get{
        if(ViewState["filter_count"] == 0){
            FilterCount = 0;
        }
        return (int)ViewState["filter_count"];
    }
    set{
        ViewState["filter_count"] = value;
    }
}

protected void RecreateFilterControlls()
{
    for(int i =0; i < FilterCount; i++){
        FilterLabel filter = LoadControl("~/Controls/FilterLabel.ascx") as FilterLabel;
        FilterList.Controls.Add(filter);
        filter.RemoveClick += new EventHandler(RemoveFilter);
    }
}


protected override void OnInit(EventArgs e)
{
    if (IsPostBack)
    {
        RecreateFilterControlls();
    }

}
// this is for button which will add new FilterLabel UserControl
protected void AddNewFilter_Click(object sender, EventArgs e)
{
    // just create filter
    AddFilter(<FilterNameTextBox|combobox>, <FilterContentTextBox>, <filterValue>);
}


public void AddFilter(string filterName, string filterContent, string filterValue = null)
{
    FilterLabel filter = LoadControl("~/Controls/FilterLabel.ascx") as FilterLabel;
    filter.ID = "Filter";
    filter.FilterContent = filterContent;
    filter.FilterName = filterName;
    filter.Value = filterValue;
    filter.RemoveClick += new EventHandler(RemoveFilter);
    // increament filter count
    FilterCount++;

}

private void RemoveFilter(object sender, EventArgs e)
{
    //some handling codes
    //remove control which caused this event
    FilterList.Controls.Remove(sender); // or you will need to ask for IndexOf(sender);
    FilterCount--;
}

the rest will be handled by ViewState it self, so you don’t need to bind data back to FilterLabel back