Question

我有一个带有员工ID的gridview和旁边的编辑按钮。单击编辑按钮时，我需要显示一个下拉列表，该列表将填充db。

中的数据

<asp:GridView ID="grvEmp" runat="server" Width="100%" GridLines="Both" 
    HeaderStyle-BackColor="#999999" AutoGenerateColumns="false"
    OnRowEditing="grvEmp_RowUpdating" OnRowUpdating="grvEmp_RowUpdating">

<Columns>
<asp:TemplateField>
<HeaderTemplate>
Employee Name
</HeaderTemplate>
<ItemTemplate>
 <%# Eval("EmployeeID")%>
</ItemTemplate>
<EditItemTemplate>
 <asp:DropDownList ID="DropDownList1" runat="server" AutoPostBack="True" OnLoad="DropDownList1_onload"
    onselectedindexchanged="DropDownList1_SelectedIndexChanged">
</asp:DropDownList>  
</EditItemTemplate>
</asp:TemplateField>
  <asp:TemplateField HeaderText="Action">
       <ItemTemplate>
        <asp:Button ID="btnEdit" Text="Edit" runat="server" CommandName="edit" /><br />
       </ItemTemplate>
       <EditItemTemplate>        
       <asp:Button ID="btnUpdate" Text="Update" runat="server" CommandName="Update" />
     </EditItemTemplate>

       </asp:TemplateField>

</Columns>

<HeaderStyle BackColor="#999999" />

</asp:GridView>

//代码隐藏

protected void grvEmp_RowDataBound(object sender, GridViewRowEventArgs e)
{

    SqlConnection cn = new System.Data.SqlClient.SqlConnection("Data Source=CHANGEME1;Initial Catalog=Reflection;Integrated Security=True");           
    SqlDataAdapter da = new SqlDataAdapter("select salary from employee",cn);
    DataSet ds = new DataSet();
    DropDownList ddl = (DropDownList)e.Row.FindControl("DropDownList1");        //null-unable to capture the control 
    da.Fill(ds);
    cn.Close();
    ddl.DataSource = ds;
    ddl.DataTextField = "salary";
    ddl.DataValueField = "salary";
    ddl.DataBind();
    ddl.Items.Insert(0, new ListItem("--Select--", "0"));
}

但是当点击编辑按钮时，不会填充下拉列表。任何人都可以提供这方面的见解吗？

Answer 1

您需要检查该行是否为datarow且处于编辑模式。您的RowDataBound方法应如下所示：

protected void grvEmp_RowDataBound(object sender, GridViewRowEventArgs e)
{
    if ((e.Row.RowType == DataControlRowType.DataRow) && ((e.Row.RowState & DataControlRowState.Edit) > 0))
    {
        SqlConnection cn = new System.Data.SqlClient.SqlConnection("Data Source=CHANGEME1;Initial Catalog=Reflection;Integrated Security=True");
        SqlDataAdapter da = new SqlDataAdapter("select salary from employee", cn);
        DataSet ds = new DataSet();
        DropDownList ddl = (DropDownList)e.Row.FindControl("DropDownList1");        //null-unable to capture the control 
        da.Fill(ds);
        cn.Close();
        ddl.DataSource = ds;
        ddl.DataTextField = "salary";
        ddl.DataValueField = "salary";
        ddl.DataBind();
        ddl.Items.Insert(0, new ListItem("--Select--", "0"));
    }
}

编辑：

你应该在RowEditing中有这样的东西：

 protected void grvEmp_RowEditing(object sender, GridViewEditEventArgs e)
  {
    //Set the edit index.
    grvEmp.EditIndex = e.NewEditIndex;
    //Bind data to the GridView control.
    BindData();
  }

编辑2：您应始终按照John Saunders在评论中的建议将Using中的连接和数据适配器包装起来，这将自动管理连接和数据适配器的生命周期，并在何时关闭/处置它超出了范围。

using (SqlConnection cn = new System.Data.SqlClient.SqlConnection("Data Source=CHANGEME1;Initial Catalog=Reflection;Integrated Security=True"))
{            
    cn.Open();
    using (SqlDataAdapter da = new SqlDataAdapter("select salary from employee", cn))
    {
        DataTable dt = new DataTable();
        da.Fill(dt);
        ddl.DataSource =dt;
        ddl.DataTextField = "salary";
        ddl.DataValueField = "salary";
        ddl.DataBind();
        ddl.Items.Insert(0, new ListItem("--Select--", "0"));
    }
}

单击datagrid视图上的编辑按钮时填充下拉列表？ - 不能捕获control-null引用

1 个答案: