Question

我在gridview中调用了一个标签，并希望从后面的代码中为该标签赋值，但是无法做到这一点。我已经创建了该gridview的rowbound：

protected void GridView1_RowDataBound(object sender, GridViewRowEventArgs e)
    {
       Label lbltotal= e.Row.FindControl("lbltotal");
        String price=Session["price"].ToString();
        DataTable dt = GridView1.DataSource as DataTable;
       lbltotal.Text = dt.Compute("sum(price)", "").ToString();
    }

我得到的错误是这样的：

（无法隐式转换类型＆＃39; System.Web.UI.Control＆＃39; System.Web.UI.WebControls.Label＆＃39;。存在显式转换（是你错过了一个演员？））

Answer 1

e.Row.FindControl返回System.Web.UI.Control，这需要明确地转换为Label控件

protected void GridView1_RowDataBound(object sender, GridViewRowEventArgs e)
{
   Label lbltotal= e.Row.FindControl("lbltotal") as Label;

   if(lbltotal != null)
   {
     String price=Session["price"].ToString();
     DataTable dt = GridView1.DataSource as DataTable;
     lbltotal.Text = dt.Compute("sum(price)", "").ToString();
   }
}

Answer 2

向其添加显式转换

protected void GridView1_RowDataBound(object sender, GridViewRowEventArgs e)
    {
       Label lbltotal= e.Row.FindControl("lbltotal") as Label; //explicit convert to label
       if(lbltotal != null)
         {
            String price=Session["price"].ToString();
            DataTable dt = GridView1.DataSource as DataTable;
           lbltotal.Text = dt.Compute("sum(price)", "").ToString();
         }
    }

Answer 3

请更改方法定义内的第1行，如下所示：

Label lbltotal= e.Row.FindControl("lbltotal") as Label;

Answer 4

你可以这样做：

protected void GridView1_RowDataBound(object sender, GridViewRowEventArgs e)
 {      
  if (e.Row.RowType == DataControlRowType.DataRow)
   {
     Label lbltotal=(Label) e.Row.FindControl("lbltotal");
     String price=Session["price"].ToString();
     DataTable dt = GridView1.DataSource as DataTable;
     lbltotal.Text = dt.Compute("sum(price)", "").ToString();
   }
 }

Answer 5

由于您正在寻找Label，因此您需要将Control从FindControl转发给它。您还应该检查行是否为DataControlRowType.DataRow，否则您也在页眉和页脚中查找标签。

protected void GridView1_RowDataBound(object sender, GridViewRowEventArgs e)
{
    if (e.Row.RowType == DataControlRowType.DataRow)
    {
        Label lbltotal= (Label)e.Row.FindControl("lbltotal");
        var allRows = ((DataRowView)e.Row.DataItem).Row.Table.AsEnumerable();
        decimal totalPrice = allRows.Sum(r => r.Field<decimal>("Price"));
        lbltotal.Text = totalPrice.ToString();
    }
}

从后面的代码为gridview内部的标签赋值

5 个答案: