Question

我正在尝试使用PagedDataSource在转发器中实现分页。问题是当我点击“下一步”按钮时页面仍然相同，它不会加载其他项目。我发现viewstate总是返回null，我不知道这是不是问题。

这是c＃代码：

public partial class Users 
{
    private int _pageSize;
    PagedDataSource page = new PagedDataSource();

    private const bool blnAllowPaging = true;
    private const int iPageSize = 3;


    protected void Page_Load(object sender, EventArgs e)
    {
        // if page is loaded for the first time call BindRepeater()
        if (!Page.IsPostBack)
        {
            // Load the table
            BindRepeater();
        }
    }


    protected void lnkFirst_Click(object sender, EventArgs e)
    {
        // Set viewstate variable to the first page
        CurrentPage = 0;
        BindRepeater();
    }

    protected void lnkPrevious_Click(object sender, EventArgs e)
    {
        // Set viewstate variable to the previous page
        CurrentPage -= 1;
        BindRepeater();
    }
    protected void lnkNext_Click(object sender, EventArgs e)
    {
        // Set viewstate variable to the next page
        CurrentPage += 1;
        BindRepeater();
    }

    protected void lnkLast_Click(object sender, EventArgs e)
    {
        // Set viewstate variable to the last page
        CurrentPage = page.PageCount - 1;
        BindRepeater();
    }
    private void FillPagesDropDownList(int iTotalPages)
    {
        ddlpageNumbers.Items.Clear();
        for (int i = 1; i <= iTotalPages; i++)
        {
            ddlpageNumbers.Items.Add(new ListItem(i.ToString(), i.ToString()));
        }
    }

    protected void ddlpageNumbers_SelectedIndexChanged(object sender, EventArgs e)
    {
        CurrentPage = ddlpageNumbers.SelectedIndex;
        BindRepeater();
    }

    private int CurrentPage
    {
        get
        {
            EnableViewState = true;
            object obj = ViewState["CurrentPage"];
            return (obj == null) ? 0 : (int)obj;
        }
        set
        {
            this.ViewState["CurrentPage"] = value;
        }
    }

    private void BindRepeater()
    {
        page.AllowPaging = blnAllowPaging;
        page.PageSize = iPageSize;

        lblTotalPages.Text = page.PageCount.ToString();
        FillPagesDropDownList(page.PageCount);

        // Disable buttons if necessary
        lnkFirst.Enabled = !page.IsFirstPage;
        lnkPrevious.Enabled = !page.IsFirstPage;
        lnkNext.Enabled = !page.IsLastPage;
        lnkLast.Enabled = !page.IsLastPage;
        // Set the PagedDataSource's current page
        page.CurrentPageIndex = CurrentPage;
        ddlpageNumbers.SelectedIndex = page.CurrentPageIndex;

        List<USERS> users = GetUsers(); // list of users taken from db
        page.DataSource = users;
        page.DataBind();

    }
}

这是asp.net代码：

<asp:Content ID="Content1" ContentPlaceHolderID="HeadContent" runat="server">
<style type="text/css">
    .style1
    {
        width: 528px;
    }
</style>
</asp:Content>
<asp:Content ID="Content2" ContentPlaceHolderID="MainContent" runat="server">
<asp:Repeater ID="m_SupportersRepeater" runat="server"  OnItemDataBound="SupportersRepeater_OnItemDataBound">
<HeaderTemplate>
    <table border="1" width="90%">
        <tr>
            <td>Name</td>
            <td>Family Name</td>
            <td>Age</td>
            <td>City</td>
        </tr>
</HeaderTemplate>

<ItemTemplate>
    <tr>
        <td><%# DataBinder.Eval(Container.DataItem, "FIRSTNAME")%></td>
        <td><%# DataBinder.Eval(Container.DataItem, "LASTNAME")%></td>
        <td><%# DataBinder.Eval(Container.DataItem, "AGE")%></td>
        <td><%# DataBinder.Eval(Container.DataItem, "CITY")%></td>
    </tr>
</ItemTemplate>

<FooterTemplate>
    </table>
</FooterTemplate>
</asp:Repeater>
<br />
<table style="margin-left: 214px">
 <tr align="center">
    <td colspan="4" class="style1">
        <asp:LinkButton ID="lnkFirst" runat="server" ForeColor="Black" Text="First" onclick="lnkFirst_Click" ></asp:LinkButton>&nbsp;
        <asp:LinkButton ID="lnkPrevious" runat="server" ForeColor="Black"  Text="Previous" OnClick="lnkPrevious_Click" >     </asp:LinkButton>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;
        Page&nbsp;
        <asp:DropDownList ID="ddlpageNumbers" runat="server" AutoPostBack="true" OnSelectedIndexChanged="ddlpageNumbers_SelectedIndexChanged">    </asp:DropDownList>&nbsp;of&nbsp;
        <asp:Label ID="lblTotalPages" runat="server">    </asp:Label>&nbsp;Pages.&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;
        <asp:LinkButton ID="lnkNext" runat="server" ForeColor="Black" Text="Next" Onclick="lnkNext_Click" ></asp:LinkButton>&nbsp;
        <asp:LinkButton ID="lnkLast" runat="server" ForeColor="Black" Text="Last" Onclick="lnkLast_Click" ></asp:LinkButton>
    </td>
</tr>
</table>
</asp:Content>

Answer 1

在BindRepeater方法中，尝试将最后三行代码（检索数据并将其绑定到PagedDataSource成员）移动到方法的顶部，以便在开始评估其属性之前填充PagedDataSource对象。我认为在方法结束时加载数据会将page.CurrentPageIndex属性重置为零。所以首先加载PagedDataSource，在PagedDataSource上设置分页属性，然后将Repeater的DataSource属性设置为PagedDataSourceObject。

在转发器中分页：viewstate返回始终为null

1 个答案: