无法将类型为“System.Web.UI.HtmlControls.HtmlInputCheckBox”的对象强制转换为“System.Web.UI.WebControls.CheckBox”。 [英] Unable to cast object of type 'System.Web.UI.HtmlControls.HtmlInputCheckBox' to type 'System.Web.UI.WebControls.CheckBox'.

问题描述

  bool  isSelected =  false ; 
  foreach （GridViewRow i  in  DataGridTrans.Rows）
 {
 CheckBox cb =  new  CheckBox（）; 
 
 cb =（CheckBox）i.FindControl（  ChkBox1）;  //  显示如上所述的错误 
  if （cb！=  null && cb.Checked）
 {
 isSelected = 真; 
  break ; 
} 
} 

解决方案

如果查看标记，您会看到复选框定义为

 <  输入   类型  = 复选框    /  >  

而不是

 <   asp：checkbox     xmlns：asp  < span class =code-keyword> = ＃unknown    /  >  

显然你是ca不要在两者之间转换 - 你必须决定使用什么并坚持下去......

尝试如下：

  var  cb =（HtmlInputCheckBox）row.FindControl（  ChkBox1）; 

投射将取决于你在aspx中如何声明它

你的ChkBox1可能是

< input type =checkboxrunat =server/> 

转换为HtmlInputCheckBox。替代方案是

< asp：Checkbox runat =server/> 

转换为Checkbox。如果你想保留你的标记，你需要在代码隐藏中使用HtmlInputCheckBox，而不是Checkbox

  //  不需要这一行 
  //   CheckBox cb = new CheckBox（）;  
 
 HtmlInputCheckBox cb =（HtmlInputCheckBox）i.FindControl（  ChkBox1）;  //  显示如上所述的错误 
 如果（cb！=  null && cb.Checked）

要使用这个你需要

使用System.Web.UI.HtmlControls; 

位于页面顶部。

bool isSelected = false;
           foreach(GridViewRow i in DataGridTrans.Rows)
           {
               CheckBox cb = new CheckBox();

         cb = (CheckBox)i.FindControl("ChkBox1");//error showing cast as mentioned above
               if (cb != null && cb.Checked)
               {
                   isSelected = true;
                   break;
               }
           }

解决方案

If you look at your markup you will see that the checkbox defined as

<input type="checkbox" />

and not as

<asp:checkbox xmlns:asp="#unknown" />

Obviously you ca nnot convert between the two -you have to decide what to use and stick to that...

Try it like:

var cb = (HtmlInputCheckBox)row.FindControl("ChkBox1");

The casting will depend on how have you declared it in your aspx

Your "ChkBox1" is probably

<input type="checkbox" runat="server"/>

which gets converted to HtmlInputCheckBox. The alternative is

<asp:Checkbox runat="server"/>

which gets converted to Checkbox. If you want to keep your markup as it is you need to use the HtmlInputCheckBox in your code-behind, not Checkbox

// don't need this line
// CheckBox cb = new CheckBox();

HtmlInputCheckBox cb = (HtmlInputCheckBox)i.FindControl("ChkBox1");//error showing cast as mentioned above
 if (cb != null && cb.Checked)

To use this you need

using System.Web.UI.HtmlControls;

at the top of your page.

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