未设置对象引用/无法将类型为“System.Web.UI.WebControls.Label”的对象强制转换为“System.IConvertible”。 [英] Object reference not set / Unable to cast object of type 'System.Web.UI.WebControls.Label' to type 'System.IConvertible'.

问题描述

我在int empId = Convert.ToInt32（labelId.Text）上得到此错误;

无法将System.Web.UI.WebControls.Label类型的对象强制转换为

''System.IConvertible''。

  protected   void  LinkBut​​ton1_Click（ object  sender，EventArgs e）
 {
  try  
 {
  int  index =  0 ; 
 
 LinkBut​​ton lb =（LinkBut​​ton）sender; 
 GridViewRow row =（GridViewRow）lb.NamingContainer; 
  if （row！=  null ）
 {
 index = row.RowIndex; 
} 
 
  var  labelId =（Label）NameDisplay.Rows [index] .FindControl（  labelGetId）; 
 labelId.Text = HiddenFieldID.Value; 
 
  int  empId = Convert.ToInt32（labelId.Text）; 
 使用（ var  db =  new  knowitCVdbEntities（））
 {
 
  var  theEmpl =（ from  
p 在 db.EMPLOYEES 
 其中 p.employee_id == empId 
 选择 p）.FirstOrDefault（）; 
 
  if （theEmpl！=  null ）
 {
 theEmpl.firstname = TextBoxFirstName.Text; 
 theEmpl.lastname = TextBoxLastName.Text; 
 
 
} 
 
} 
} 
  catch （例外x） 
 {
 LabelError.Visible =  true ; 
 LabelError.Text = x.Message; 
} 
 
 
} 
} 
} 

解决方案

< blockquote>为什么不直接从HiddenFieldID.Value转换empID而不是将标签设置为该值然后再将其拉回？看起来好像很多，无所事事......

i get this error on int empId = Convert.ToInt32(labelId.Text);
Unable to cast object of type ''System.Web.UI.WebControls.Label'' to type
''System.IConvertible''.

protected void LinkButton1_Click(object sender, EventArgs e)
        {
            try
            {
                int index = 0;

                LinkButton lb = (LinkButton) sender;
                GridViewRow row = (GridViewRow) lb.NamingContainer;
                if (row != null)
                {
                    index = row.RowIndex;
                }

                var labelId = (Label) NameDisplay.Rows[index].FindControl("labelGetId");
                labelId.Text = HiddenFieldID.Value;
                
                int empId = Convert.ToInt32(labelId.Text);
                using (var db = new knowitCVdbEntities())
                {

                    var theEmpl = (from
                                       p in db.EMPLOYEES
                                   where p.employee_id == empId
                                   select p).FirstOrDefault();

                    if (theEmpl != null)
                    {
                        theEmpl.firstname = TextBoxFirstName.Text;
                        theEmpl.lastname = TextBoxLastName.Text;


                    }

                }
            }
            catch (Exception x)
            {
                LabelError.Visible = true;
                LabelError.Text = x.Message;
            }
            

            }
        }
    }

解决方案

Why not just convert the empID from HiddenFieldID.Value instead of setting the label to that value then pulling it back out again? Seems like a lot of round-about for nothing...

这篇关于未设置对象引用/无法将类型为“System.Web.UI.WebControls.Label”的对象强制转换为“System.IConvertible”。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！