如何检查的ContentPlaceHolder是空的？ [英] How to check if ContentPlaceHolder is empty?

问题描述

如何检查的ContentPlaceHolder绝对是空的？

How to check if ContentPlaceHolder is absolutely empty?

在的ContentPlaceHolder只有文字，没有标签和控制。

In the ContentPlaceHolder have text only, without tags and controls.

例Page.Master：

Example Page.Master:

<asp:ContentPlaceHolder runat="server" ID="Content" />

例如Test.aspx文件中：

Example Test.aspx:

<asp:Content runat="server" ContentPlaceHolderID="Content">
    Custom text without controls. Content.Controls.Count is 0 and Content.HasControls is false.
</asp:Content>

我需要做的是，当占位符是空放了默认的内容是另一个控制。

What I need to do is that when the placeholder is empty put a default content is in another control.

覆盖试过两次相同的占位符，但我得到的错误，当动态负载。

Overwrite tried twice for the same placeholder but I get error when dynamic load.

推荐答案

您可以实现将呈现内容控制成一个字符串的方法，然后检查字符串找到wheahter它包含任何非空白字符：

You can implement a method that will render the content control into a string, then check the string to find wheahter it contains any non-white space chars:

private bool HasContent(Control ctrl)
{
    var sb = new System.Text.StringBuilder();
    using (var sw = new System.IO.StringWriter(sb)) 
    {
        using(var tw = new HtmlTextWriter(sw))
        {
            ctrl.RenderControl(tw);
        }
    }

    var output = sb.ToString().Trim();

    return !String.IsNullOrEmpty(output);
}

protected void Page_PreRender(object sender, EventArgs e)
{
    var placeholder = Master.FindControl("FeaturedContent");
    var hasContent = HasContent(placeholder);
}

这篇关于如何检查的ContentPlaceHolder是空的？的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！