C# 从RowCommand上嵌套的GridView中的DropDownList中检索值

我有一个嵌套的GridView（

GvMP\u Summary\u Items

）。每行包含一个DropDownList。DropDownList以嵌套GridView的RowDataBound事件为界

每行还包含一个按钮。在RowCommand事件上按下此按钮后，我希望找到DropDownList的当前选定值，以便在代码中进一步使用它

我的代码将只获取每行DropDownList的默认值，当前每行的DropDownList设置为

0

以下是RowCommand事件：

Protected Sub GvMP_Summary_Items_RowCommand(sender As Object, e As GridViewCommandEventArgs)

  Dim lb As ImageButton = CType(e.CommandSource, ImageButton)
  Dim gvRow As GridViewRow = lb.BindingContainer //Getting current row to get index       

  Dim GvMP_Summary_Items As GridView = CType(gvRow.FindControl("GvMP_Summary_Items"), GridView)

  Dim intMPItem_Qty As Integer = CType(gvRow.FindControl("cboMPItem_Qty"), DropDownList).SelectedValue
  Dim strMPItem_Qty As String = CType(gvRow.FindControl("txtMPItem_Qty"), TextBox).Text

End Sub

我甚至在GridView行中包含了一个默认值为空的文本框。尽管是在行上，但如果输入了某些内容，在行上的命令事件会返回前面带有逗号（，）的值

这证明我选择了正确的行，并且可以从文本框而不是下拉列表中检索值

我有什么遗漏吗？为什么我可以返回在文本框中输入的值而不是DropDownList的选定值？还有，为什么文本框值前面有逗号（，）

注意：在上述情况下，代码是用VB编写的，所以答案是用VB而不是C#，但我可以接受两者

重要事项：

在页面加载方法中绑定父GridView

在父GridView的行数据绑定事件中绑定子GridView

在子GridView的行数据绑定事件中绑定DropDownList

将命令名添加到子GridView中的按钮中

最后，在子GridView的RowCommand事件中

• 获取子GridView的行
• 然后从子GridView的行中查找子GridView中的所有控件

我不太了解VB.NET，所以我添加了一个带有RowCommand事件的嵌套GridView示例（c#）（希望OP可以在VB.NET中使用它）：

HTML代码（.Aspx）：

注意：上面的DropDownList选择的是选定的值而不是文本。
通过将
行命令的
命令源
返回到按钮，然后从该按钮中获取正确的行，可以很容易地完成此操作。获得行后，您可以使用
FindControl
查找
DropDownList
。这适用于嵌套项的每个级别，也适用于顶部控件

VB

Protected Sub GMP_Summary_Items_RowCommand(ByVal sender As Object, ByVal e As GridViewCommandEventArgs)

    'cast the commandsource back to a button
    Dim btn As Button = CType(e.CommandSource,Button)

    'get the current gridviewrow from the button namingcontainer
    Dim row As GridViewRow = CType(btn.NamingContainer,GridViewRow)

    'use findcontrol to locate the dropdownlist in that row
    Dim ddl As DropDownList = CType(row.FindControl("cboMPItem_Qty"),DropDownList)

    'show the selected value of the dropdownlist
    Label1.Text = ddl.SelectedValue

End Sub

代码是用a从C#翻译过来的，所以可能不是100%准确

C#

您确实需要将数据绑定到
IsPostBack
检查，否则每次回发时数据都会反弹到DDL，并且所选值丢失

您是如何填充dropdownlist的？是否有可能在每次回发时都将其清除并重新填充，并将其重置为默认值？
DataTable TempDT = new DataTable();

protected void Page_Load(object sender, EventArgs e)
{
    CreateDataTable();

    if (!IsPostBack)
    {
        GridView_Outer.DataSource = TempDT;
        GridView_Outer.DataBind();
    }
}

// create DataTable
public void CreateDataTable()
{
    TempDT = new DataTable();
    TempDT.Columns.Add("Label_Outer");
    TempDT.Columns.Add("Label_Inner");
    TempDT.Columns.Add("TextBox_Inner");

    TempDT.Rows.Add("OuterLabel", "InnerLabel", "");
    TempDT.Rows.Add("OuterLabel", "InnerLabel", "");

    // store DataTable into ViewState to prevent data loss on PostBack
    ViewState["DT"] = TempDT;
}

// Calls Outer GridView on Data Binding
protected void GridView_Outer_RowDataBound(object sender, GridViewRowEventArgs e)
{
    // check if gridview row is not in edit mode
    if (e.Row.RowType == DataControlRowType.DataRow)
    {
        // Get Outer GrridView 's controls
        Label Label_Outer = (Label)e.Row.FindControl("Label_Outer");
        GridView GridView_Inner = (GridView)e.Row.FindControl("GridView_Inner");

        // get DataTable from ViewState and set to Inner GridView
        GridView_Inner.DataSource = (DataTable)ViewState["DT"];
        GridView_Inner.DataBind();
    }
}

// Calls Inner GridView on Data Binding
protected void GridView_Inner_RowDataBound(object sender, GridViewRowEventArgs e)
{
    // check if gridview row is not in edit mode
    if (e.Row.RowType == DataControlRowType.DataRow)
    {
        // Get Outer GrridView 's controls
        DropDownList DropDownList_Inner = (DropDownList)e.Row.FindControl("DropDownList_Inner");

        // Create a DataTable to Bind data for DropDownlist
        DataTable TempDDLDT = new DataTable();
        TempDDLDT.Columns.Add("ItemText");
        TempDDLDT.Columns.Add("ItemValue");

        TempDDLDT.Rows.Add("ItemText1", "ItemValue1");
        TempDDLDT.Rows.Add("ItemText2", "ItemValue2");

        // bind DataTable to the DropDownList
        DropDownList_Inner.DataSource = TempDDLDT;
        DropDownList_Inner.DataTextField = "ItemText";
        DropDownList_Inner.DataValueField = "ItemValue";
        DropDownList_Inner.DataBind();
    }
}

// Calls when Inner GridView 's button clicked
protected void GridView_Inner_RowCommand(object sender, GridViewCommandEventArgs e)
{
    // get Inner GridView 's clicked row
    GridViewRow InnerGridViewRow = (GridViewRow)(((Control)e.CommandSource).NamingContainer);

    // get Inner GridView 's controls from clicked row
    TextBox TextBox_Inner = (TextBox)InnerGridViewRow.FindControl("TextBox_Inner");
    DropDownList DropDownList_Inner = (DropDownList)InnerGridViewRow.FindControl("DropDownList_Inner");

    // check if correct button is clicked
    if (e.CommandName == "BtnInnerCmd")
    {
        string DropDownListValue = DropDownList_Inner.SelectedValue;
        string TextBoxValue = TextBox_Inner.Text;

        Label_Result.Text = "DropDownList 's Selected Value is " + DropDownListValue +
                            "<br />TextBox 's Entered Value is " + TextBoxValue;
    }
}

Protected Sub GMP_Summary_Items_RowCommand(ByVal sender As Object, ByVal e As GridViewCommandEventArgs)

    'cast the commandsource back to a button
    Dim btn As Button = CType(e.CommandSource,Button)

    'get the current gridviewrow from the button namingcontainer
    Dim row As GridViewRow = CType(btn.NamingContainer,GridViewRow)

    'use findcontrol to locate the dropdownlist in that row
    Dim ddl As DropDownList = CType(row.FindControl("cboMPItem_Qty"),DropDownList)

    'show the selected value of the dropdownlist
    Label1.Text = ddl.SelectedValue

End Sub

protected void GMP_Summary_Items_RowCommand(object sender, GridViewCommandEventArgs e)
{
    //cast the commandsource back to a button
    Button btn = e.CommandSource as Button;

    //get the current gridviewrow from the button namingcontainer
    GridViewRow row = btn.NamingContainer as GridViewRow;

    //use findcontrol to locate the dropdownlist in that row
    DropDownList ddl = row.FindControl("cboMPItem_Qty") as DropDownList;

    //show the selected value of the dropdownlist
    Label1.Text = ddl.SelectedValue;
}