[英]Populating Gridview's Drop Down List depending on database value
我想在我的代码中获得一些帮助,我想做的是填充我的下拉列表,该列表显示可用数量(存储在数据库中)但是当我尝试在行中找到控件时,我得到一个 null参考异常它说行是 null。
这是包含我的下拉列表的模板字段
<asp:TemplateField HeaderText="Quantity" SortExpression="Quantity">
<EditItemTemplate>
<asp:DropDownList ID="ddlQuantity" runat="server">
</asp:DropDownList>
</EditItemTemplate>
<ItemTemplate>
<asp:Label ID="Label4" runat="server" Text='<%# Bind("Quantity") %>'></asp:Label>
</ItemTemplate>
</asp:TemplateField>
和我背后的代码
protected void Cart_GV_RowEditing(object sender, GridViewEditEventArgs e) {
Cart_GV.EditIndex = e.NewEditIndex;
GridViewRow row = (sender as Control).Parent.Parent as GridViewRow;
DropDownList ddlQuantity = row.FindControl("ddlQuantity") as DropDownList;
string cartitemid = Cart_GV.DataKeys[e.NewEditIndex].Value.ToString();
conn.Open();
SqlCommand checkQuantity = new SqlCommand("SELECT OnHandQTY FROM Inventory INNER JOIN Cart_Item ON Inventory.ProductID = Cart_Item.ProductID WHERE CartItemID = '" + cartitemid + "';", conn);
int availalbleQuantity = (int)checkQuantity.ExecuteScalar();
conn.Close();
for (int i = 1; i <= availalbleQuantity; i++) {
ListItem item = new ListItem(i.ToString(), i.ToString());
ddlQuantity.Items.Add(item);
}
ViewUserCart();
}
请试试这个
protected void Cart_GV_RowEditing(object sender, GridViewEditEventArgs e) {
Cart_GV.EditIndex = e.NewEditIndex;
GridViewRow row = (sender as Control).Parent.Parent as GridViewRow;
DropDownList ddlQuantity = row.FindControl("ddlQuantity") as DropDownList;
string cartitemid = Cart_GV.DataKeys[e.NewEditIndex].Value.ToString();
conn.Open();
SqlCommand cmd = new SqlCommand("SELECT OnHandQTY FROM Inventory INNER JOIN Cart_Item ON Inventory.ProductID = Cart_Item.ProductID WHERE CartItemID = '" + cartitemid + "';", conn);
SqlDataAdapter sda = new SqlDataAdapter(cmd);
DataTable dt = new DataTable();
sda.Fill(dt);
con.Close();
ddlQuantity.DataSource = dt;
ddlQuantity.DataTextField = "OnHandQTY";
ddlQuantity.DataValueField = "OnHandQTY";
ddlQuantity.DataBind();
ViewUserCart();
}
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