每点击“+”一次，Gridview就自动添加一行，并能保存原有的数据 （40）
在Page_Load中，先生成一个datatable，然后与gridview绑定。
DataTable stoveTable = new DataTable();
stoveTable.Columns.Add("usage", typeof(DropDownList));
stoveTable.Columns.Add("steelKind", typeof(DropDownList));
stoveTable.Columns.Add("castingTon", typeof(TextBox));
DataRow newRow = stoveTable.NewRow();
stoveTable.Rows.Add(newRow);
this.GridView_list.DataSource = stoveTable;
this.GridView_list.DataBind();
如图：
目标：每点击“+”一次，就自动添加一行，而且如果前面各行的Dropdownlist中的数据已改变，或者textbox中已输入数据，则要求能保留住这些数据，解决方法：
（1）把数据读到datatable中，用viewstate记录状态，问题：Dropdownlist中的数据已改变或者textbox中已输入数据后，如何更新到viewstate中？？
add_Click(object sender, EventArgs e)
{
DataTable newTable =this.ViewState["stoveTable"] as DataTable;
DataRow newRow = newTable.NewRow();
newTable.Rows.Add(newRow);
this.GridView_list.DataSource = newTable;
this.GridView_list.DataBind();
this.ViewState["stoveTable"] = newTable;
}
这样写能实现添加新的一行，可是，原有的行的数据也会一起被初始化。
[解决办法]
下面是一个完整的例子，拷贝存储xx.aspx执行即可
<%@ Page Language="C#" EnableViewState="true" %>
<%@ Import Namespace="System.Data" %>
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<script runat="server">
protected void Page_Load(object sender, EventArgs e)
{
if (!Page.IsPostBack)
{
DataTable stoveTable = new DataTable();
stoveTable.Columns.Add("usage", typeof(String));
stoveTable.Columns.Add("steelKind", typeof(String));
stoveTable.Columns.Add("castingTon", typeof(String));
DataRow newRow = stoveTable.NewRow();
stoveTable.Rows.Add(newRow);
this.GridView_list.DataSource = stoveTable;
this.GridView_list.DataBind();
ViewState["dt"] = stoveTable;
}
}
protected void GridView_list_RowDataBound(object sender, GridViewRowEventArgs e)
{
if (e.Row.RowType == DataControlRowType.DataRow)
{
String usage = DataBinder.Eval(e.Row.DataItem, "usage").ToString();
String steelKind = DataBinder.Eval(e.Row.DataItem, "steelKind").ToString();
String castingTon = DataBinder.Eval(e.Row.DataItem, "castingTon").ToString();
DropDownList x1 = e.Row.FindControl("x1") as DropDownList;
DropDownList x2 = e.Row.FindControl("x2") as DropDownList;
TextBox x3 = e.Row.FindControl("x3") as TextBox;
x3.Text = castingTon;
ListItem xx1 = x1.Items.FindByValue(usage);
if (xx1 != null) xx1.Selected = true;
ListItem xx2 = x2.Items.FindByValue(steelKind);
if (xx2 != null) xx2.Selected = true;
}
}
protected void LinkButton1_Click(object sender, EventArgs e)
{
GridViewRow r = GridView_list.Rows[GridView_list.Rows.Count - 1];
DropDownList x1 = r.FindControl("x1") as DropDownList;
DropDownList x2 = r.FindControl("x2") as DropDownList;
TextBox x3 = r.FindControl("x3") as TextBox;
if (ViewState["dt"] == null)
{
Response.Write("Error");
return;
}
DataRow newRow;
DataTable stoveTable = (DataTable)ViewState["dt"];
newRow = stoveTable.Rows[stoveTable.Rows.Count - 1];
newRow["usage"] = x1.SelectedValue;
newRow["steelKind"] = x2.SelectedValue;
newRow["castingTon"] = x3.Text;
//if (stoveTable.Rows.Count < 1) stoveTable.Rows.Add(newRow);
newRow = stoveTable.NewRow();
stoveTable.Rows.Add(newRow);
ViewState["dt"] = stoveTable;
this.GridView_list.DataSource = stoveTable;
this.GridView_list.DataBind();
}
protected void LinkButton2_Click(object sender, EventArgs e)
{
if (ViewState["dt"] == null)
{
Response.Write("Error");
return;
}
DataTable stoveTable = (DataTable)ViewState["dt"];
if (stoveTable.Rows.Count < 2) return;
stoveTable.Rows.RemoveAt(stoveTable.Rows.Count - 1);
ViewState["dt"] = stoveTable;
this.GridView_list.DataSource = stoveTable;
this.GridView_list.DataBind();
}
protected void x1_SelectedIndexChanged(object sender, EventArgs e)
{
DropDownList x1 = sender as DropDownList;
GridViewRow r = x1.Parent.Parent as GridViewRow;
if (ViewState["dt"] == null)
{
Response.Write("Error");
return;
}
DataTable stoveTable = (DataTable)ViewState["dt"];
stoveTable.Rows[r.RowIndex]["usage"] = x1.SelectedValue;
ViewState["dt"] = stoveTable;
this.GridView_list.DataSource = stoveTable;
this.GridView_list.DataBind();
}
protected void x2_SelectedIndexChanged(object sender, EventArgs e)
{
DropDownList x2 = sender as DropDownList;
GridViewRow r = x2.Parent.Parent as GridViewRow;
if (ViewState["dt"] == null)
{
Response.Write("Error");
return;
}
DataTable stoveTable = (DataTable)ViewState["dt"];
stoveTable.Rows[r.RowIndex]["steelKind"] = x2.SelectedValue;
ViewState["dt"] = stoveTable;
this.GridView_list.DataSource = stoveTable;
this.GridView_list.DataBind();
}
protected void x3_TextChanged(object sender, EventArgs e)
{
TextBox x3 = sender as TextBox;
GridViewRow r = x3.Parent.Parent as GridViewRow;
if (ViewState["dt"] == null)
{
Response.Write("Error");
return;
}
DataTable stoveTable = (DataTable)ViewState["dt"];
stoveTable.Rows[r.RowIndex]["castingTon"] = x3.Text;
ViewState["dt"] = stoveTable;
this.GridView_list.DataSource = stoveTable;
this.GridView_list.DataBind();
}
</script>
<html xmlns="http://www.w3.org/1999/xhtml">
<head id="Head1" runat="server">
<title></title>
</head>
<body>
<form id="form1" runat="server">
<asp:GridView ID="GridView_list" runat="server" ShowFooter="false" AutoGenerateColumns="false"
OnRowDataBound="GridView_list_RowDataBound">
<Columns>
<asp:TemplateField>
<ItemTemplate>
<asp:DropDownList ID="x1" runat="server" AutoPostBack="true" OnSelectedIndexChanged="x1_SelectedIndexChanged">
<asp:ListItem>L0</asp:ListItem>
<asp:ListItem>L1</asp:ListItem>
<asp:ListItem>L2</asp:ListItem>
<asp:ListItem>L3</asp:ListItem>
</asp:DropDownList>
</ItemTemplate>
</asp:TemplateField>
<asp:TemplateField>
<ItemTemplate>
<asp:DropDownList ID="x2" runat="server" AutoPostBack="true" OnSelectedIndexChanged="x2_SelectedIndexChanged">
<asp:ListItem>10#</asp:ListItem>
<asp:ListItem>20#</asp:ListItem>
<asp:ListItem>30#</asp:ListItem>
<asp:ListItem>40#</asp:ListItem>
</asp:DropDownList>
</ItemTemplate>
</asp:TemplateField>
<asp:TemplateField>
<ItemTemplate>
<asp:TextBox ID="x3" runat="server" AutoPostBack="true" OnTextChanged="x3_TextChanged"></asp:TextBox>
</ItemTemplate>
</asp:TemplateField>
</Columns>
</asp:GridView>
<asp:LinkButton ID="LinkButton1" runat="server" Text="+" OnClick="LinkButton1_Click"></asp:LinkButton>
<asp:LinkButton ID="LinkButton2" runat="server" Text="-" OnClick="LinkButton2_Click"></asp:LinkButton>
</form>
</body>
</html>