如何创建基于属性显示页眉,页脚的自定义中继器？

Question

我想创建一个Repeater,它根据属性显示页眉/页脚,只有当它DataSource为空时.

public class Repeater : System.Web.UI.WebControls.Repeater
{
    public bool ShowHeaderOnEmpty { get; set; }
    public bool ShowFooterOnEmpty { get; set; }

    [DefaultValue((string)null),
    PersistenceMode(PersistenceMode.InnerProperty),
    TemplateContainer(typeof(System.Web.UI.WebControls.RepeaterItem)),
    Browsable(false)]
    public ITemplate EmptyTemplate { get; set; }
}

我也想创建一个EmptyTemplate,如果DataSource是空显示这个模板...

我不知道如何实现这一点.我应该覆盖什么来实现这种行为？

Answer 1

[ToolboxData("<{0}:SmartRepeater runat=\"server\"></{0}:SmartRepeater>")]
public partial class SmartRepeater : Repeater
{
    public bool ShowHeaderOnEmpty { get; set; }
    public bool ShowFooterOnEmpty { get; set; }

    private ITemplate emptyTemplate = null;

    [PersistenceMode(PersistenceMode.InnerProperty)]
    public ITemplate EmptyTemplate
    {
        get { return this.emptyTemplate; }
        set { this.emptyTemplate = value; }
    }

    protected override void OnDataBinding(EventArgs e)
    {
        base.OnDataBinding(e);
        if (this.Items.Count == 0)
        {
            this.Controls.Clear();

            if (this.HeaderTemplate != null && ShowHeaderOnEmpty)
                this.HeaderTemplate.InstantiateIn(this);

            if (this.EmptyTemplate!=null)
                this.EmptyTemplate.InstantiateIn(this);

            if (this.FooterTemplate != null && ShowFooterOnEmpty)
                this.FooterTemplate.InstantiateIn(this);
        }
    }
}

用法：

<UC:SmartRepeater ID="rep" runat="server" ShowHeaderOnEmpty="true" ShowFooterOnEmpty="true">
    <HeaderTemplate>HEADER</HeaderTemplate>
    <ItemTemplate>Item</ItemTemplate>
    <SeparatorTemplate>, </SeparatorTemplate>
    <EmptyTemplate><b>Nothing</b></EmptyTemplate>
    <FooterTemplate>FOOTER</FooterTemplate>
</UC:SmartRepeater>