使用＆LT;％=％GT;或LT;％＃％＆GT;在ASP.NET RUNAT =服务器 [英] using <%= %> or <%# %> with runat=server in ASP.NET

问题描述

我有一个Web控制，看起来像这样

I have a web control that looks like this

public class Foo : WebControl
{
  [Bindable(true)]
  [Category("Default")]
  [DefaultValue("")]
  [Localizable(true)]
  public string Bar { get; set; }

  protected override void Render(HtmlTextWriter output)
  {
    output.WriteLine(Bar);
  }
}

我想把这个三夏在我的aspx页面像这样：

I want to put this webcontrol in my aspx page like so:

<cc1:Foo Bar="<%= Fa.La.La %>/otherstuff" runat="server" />

（显然这code简化为显示问题）

(obviously this code is simplified to show the problem)

在我的Render方法变量Fa.La.La未评估。它的到来作为原始文本＆LT;％= Fa.La.La％>我怎么评价它？

In my Render method the variable Fa.La.La is not evaluated. It's coming in as the raw text "<%= Fa.La.La %>" How do I evaluate it?

我不是特别的变量是如何传递如果变量如果他们在为＆lt传递进行评估;％＃...％>，工作正常。问题的关键是我有之前我要评估一些服务器端的变量/而我的渲染（）方法被调用。

I'm not particular how the variables are passed in. If the variables can be evaluated if they are passed in as <%# ... %>, that works fine. The point is I have some server-side variables I want evaluated before/while my Render() method is called.

我能想到的唯一的事情就是用正则表达式抢的内容和LT;％= ...％>和使用反射或东西，但必须有一个更优雅的方式来做到这一点

The only thing I can think of is to use a regex to grab the contents of <%= ... %> and use reflection or something, but there has to be a more elegant way to do this.

这个问题是类似于A HREF＆LT使用服务器变量来 pretty;％= XX％＆GT;与RUNAT =服务器，但它不是完全一样的，因为没有一个答案有有益的。

This question is pretty similar to using server variables in a href <%= xx %> with runat=server, but it's not exactly the same since none of the answers there were useful.

推荐答案

您应该使用绑定前pression ＆LT;％＃EXPR％GT; 。

You should have to use binding expression <%# expr %>.

<cc1:Foo Bar='<%# String.Concat(Fa.La.La,"/otherstuff")%>' runat="server" /> 

和呼叫的DataBind（）方法code-落后。

and call DataBind() method in code-behind.

public void page_load()
{
  DataBind();
}

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