ASP.NET在绑定时使用条件表达式
Asp.net2.0不支持在数据绑定时的条件表达式。Asp.net 4.0已经平滑地解决这个问题，不用修改代码。
下面让我们来看一个简单的ASP.NET数据绑定场景，有这么一个Repeater：
1: <asp:Repeater runat="server" ID="itemsList">
2: <HeaderTemplate>
3: <table border="1" cellspacing="0" cellpadding="5">
4: </HeaderTemplate>
5: <ItemTemplate>
6: <tr>
7: <td align="right">
8: <%# Container.ItemIndex + 1 %>.
9: </td>
10: <td>
11: <%# Eval("Title") %>
12: </td>
13: </tr>
14: </ItemTemplate>
15: <FooterTemplate>
16: </table>
17: </FooterTemplate>
18: </asp:Repeater>
然后后端的cs:
1: protected void Page_Load(object sender, EventArgs e)
2: {
3: var items = new[] {
4: new { Id = 1, Title = "Headline 1" },
5: new { Id = 2, Title = "Headline 2" },
6: new { Id = 2, Title = "Headline 3" },
7: new { Id = 2, Title = "Headline 4" },
8: new { Id = 2, Title = "Headline 5" }
9: };
10: itemsList.DataSource = items;
11: itemsList.DataBind();
12: }
当我们需要判断绑定时数据行，我们需要Create这么一个类似的方法或函数：
1: /// <summary>
2: /// Iifs the specified condition.
3: /// </summary>
4: /// <param name="condition">if set to <c>true</c> [condition].</param>
5: /// <param name="trueResult">The true result.</param>
6: /// <param name="falseResult">The false result.</param>
7: /// <returns></returns>
8: protected object Iif(bool condition, object trueResult, object falseResult)
9: {
10: return condition ? trueResult : falseResult;
11: }
然后在ASPX中使用它：
1: <asp:Repeater runat="server" ID="Repeater1">
2: <HeaderTemplate>
3: <table border="1" cellspacing="0" cellpadding="5">
4: </HeaderTemplate>
5: <ItemTemplate>
6: <tr style='background-color: <%# Iif(Container.ItemIndex % 2==0, "white", "whitesmoke") %>'>
7: <td align="right">
8: <%# Container.ItemIndex + 1 %>.</td>
9: <td>
10: <%# Eval("Title") %></td>
11: </tr>
12: </ItemTemplate>
13: <FooterTemplate>
14: </table>
15: </FooterTemplate>
16: </asp:Repeater>
这是在模仿VB中的IIF函数。到了ASP.NET 4.0中，我们可以直接这么写了：
1: <asp:Repeater runat="server" ID="Repeater2">
2: <HeaderTemplate>
3: <table border="1" cellspacing="0" cellpadding="5">
4: </HeaderTemplate>
5: <ItemTemplate>
6: <tr style='background-color:<%# Container.ItemIndex % 2==0 ? "white" : "whitesmoke" %>'>
7: <td align="right">
8: <%# Container.ItemIndex + 1 %>.</td>
9: <td>
10: <%# Eval("Title") %></td>
11: </tr>
12: </ItemTemplate>
13: <FooterTemplate>
14: </table>
15: </FooterTemplate>
16: </asp:Repeater>
好了，这个演示是基于ASP.NET WebForm 数据绑定时条件表达式的实现。希望这篇POST对您有帮助！
Author: Petter Liu http://wintersun.cnblogs.com