ASP.Net : DataPager Control always a step behind with paging

Take the following example...a page with a `ListView` and a `DataPager` used for paging the data of the `ListView`:

*Code Behind:*

protected void Page_Load(object sender, EventArgs e)
{
MyList.DataSource = GetSomeList();
MyList.DataBind();
}

*Source:*

<asp:ListView ID="MyList" runat="server">
<% //LayoutTemplate and ItemTemplate removed for the example %>
</asp:ListView>

<asp:DataPager ID="ListPager" PagedControlID="MyList" runat="server" PageSize="10">
<Fields>
<asp:NumericPagerField />
</Fields>
</asp:DataPager>

The problem with the `DataPager` is that it is always a step-behind with the binding.

For example, when the page loads it's on page number 1. Then when you click on page 3, it stays on page 1 after the postback. Then you click on page 5, and after the postback it finds itself on page 3...and after that you click on page 6, and it finds itself on page 5...and so on and so forth.

Why isn't the paging working as expected?

Solution
------------


The problem is due to the binding occuring on the `Page_Load` event.

For this to work as expected, **the binding needs to happen in the `DataPager`'s `OnPreRender` event**, not in the `Page_Load`.


*Source:*

<asp:DataPager ID="ListPager" PagedControlID="MyList" runat="server" PageSize="10"
OnPreRender="ListPager_PreRender">

<Fields>
<asp:NumericPagerField />
</Fields>
</asp:DataPager>

*Code Behind:*

protected void Page_Load(object sender, EventArgs e)
{
//Binding code moved from Page_Load
//to the ListView's PreRender event
}

protected void ListPager_PreRender(object sender, EventArgs e)
{
MyList.DataSource = GetSomeList();
MyList.DataBind();
}

I ran into this same problem, but binding everytime on datapager prerender was not an option for me. Instead, I was able to accomplish much the same thing by binding only when the paging occurred. This solution can be used as an alternative to the prerender solution by Andreas. The following worked for me:

By attaching to the ListView's PagePropertiesChanged event, I was able to correct the paging issue without having to bind on every prerender of the data pager.

**NOTE:** Most of the data pager properties are setup in a skin file, which is why they are not in the markup.

*Markup:*

<asp:DataPager ID="ListPager" runat="server" PagedControlID="MyList" />
<asp:ListView ID="MyList" runat="server">
<% //LayoutTemplate and ItemTemplate removed for the example %>
</asp:ListView>

*Code Behind:*

protected void Page_Load(object sender, EventArgs e) {
MyList.PagePropertiesChanged += new EventHandler(MyList_PagePropertiesChanged);
}

/// <summary>
/// Handles the situation where the page properties have changed. Rebind the data
/// </summary>
/// <param name="sender"></param>
/// <param name="e"></param>
private void MyList_PagePropertiesChanged(object sender, EventArgs e) {
MyList.DataSource = GetSomeList();
MyList.DataBind();
}

You are missing the OnPreRender event on the datapager!

in the page load you should put the code between
if (!IsPostBack)
{
}


It will solve your problem.

**Following works perfect for me.**

Protected Sub Page_Load(ByVal sender As Object, ByVal e As System.EventArgs) Handles Me.Load
Dim ds As DataSet
ds = SQLHELPER.ExecuteDataSet(CommandType.StoredProcedure, "sp_Locations")
rs.EnableViewState = False
rs.DataSource = ds
rs.DataBind()
End Sub

Protected Sub rs_PagePropertiesChanging(ByVal sender As Object, ByVal e As PagePropertiesChangingEventArgs)
'set current page startindex, max rows and rebind to false
Pager.SetPageProperties(e.StartRowIndex, e.MaximumRows, False)
'rebind List View
rs.DataBind()
End Sub

<asp:ListView ID="rs" runat="server" onpagepropertieschanging="rs_PagePropertiesChanging">

Alternatively, if you are building a **User control** only containing the ListView, you can simply point the pager event handler to the `Page_Load` method, since the Page_Load method isn't running anything else:

<asp:DataPager ID="ListPager" PagedControlID="MyList" runat="server" PageSize="10"
OnPreRender="Page_Load">