将网格视图的两列相乘，并将其显示在新列中
Multiplying Two Columns of a gridview and show it in a new column
我想对网格视图的两列进行多列，并在第三列中显示它。我面临的问题在行数据绑定代码中显示了空引用异常的错误。如何解决？这在我的.cs代码中
using System;
using System.Collections;
using System.Configuration;
using System.Data;
using System.Data.SqlClient;
using System.Linq;
using System.Web;
using System.Web.Security;
using System.Web.UI;
using System.Web.UI.HtmlControls;
using System.Web.UI.WebControls;
using System.Web.UI.WebControls.WebParts;
using System.Xml.Linq;
using System.Globalization;
public partial class ProjectBilling : System.Web.UI.Page
{
SqlConnection con = new SqlConnection(ConfigurationManager.ConnectionStrings["SQLDbConnection"].ConnectionString);
protected void Page_Load(object sender, EventArgs e)
{
if (!Page.IsPostBack)
{
//AppSettingsReader configReader = new AppSettingsReader();
}
}
protected void GridView1_RowDataBound(object sender, GridViewRowEventArgs e)
{
if (e.Row.RowType == DataControlRowType.DataRow)
{
TextBox txtHour = (TextBox)e.Row.FindControl("Hour");
TextBox txtrate = (TextBox)e.Row.FindControl("RatePerHour");
TextBox TextBoxInsertTotal = (TextBox)e.Row.FindControl("Total");
txtHour.Attributes["onKeyup"] = "javascript: return multiplication('" + Convert.ToInt32(txtHour.Text) + "','" + Convert.ToDouble(txtrate.Text) + "','" + Convert.ToInt32(TextBoxInsertTotal.ClientID) + "')";
txtrate.Attributes["onKeyup"] = "javascript: return multiplication('" + Convert.ToInt32(txtHour.Text) + "','" + Convert.ToDouble(txtrate.Text) + "','" + Convert.ToInt32(TextBoxInsertTotal.ClientID) + "')";
}
}
private DataSet GetData(string query)
{
string conString = ConfigurationManager.ConnectionStrings["SQLDbConnection"].ConnectionString;
SqlCommand cmd = new SqlCommand(query);
using (SqlConnection con = new SqlConnection(conString))
{
using (SqlDataAdapter sda = new SqlDataAdapter())
{
cmd.Connection = con;
sda.SelectCommand = cmd;
using (DataSet ds = new DataSet())
{
sda.Fill(ds);
return ds;
}
}
}
}
protected double CalculateTotal(double RatePerHour, int Hour)
{
return RatePerHour * Hour;
}
protected void Add_Click(object sender, EventArgs e)
{
try
{
SqlDataSource1.InsertParameters["Hour"].DefaultValue =
((TextBox)GridView1.FooterRow.FindControl("txtHour")).Text;
SqlDataSource1.InsertParameters["ProjectType"].DefaultValue =
((DropDownList)GridView1.FooterRow.FindControl("ddlName")).SelectedValue;
SqlDataSource1.InsertParameters["ProjectName"].DefaultValue =
((TextBox)GridView1.FooterRow.FindControl("projectnameTextBox")).Text;
SqlDataSource1.InsertParameters["Month"].DefaultValue =
((DropDownList)GridView1.FooterRow.FindControl("ddlmonth")).SelectedValue;
SqlDataSource1.InsertParameters["Year"].DefaultValue =
((DropDownList)GridView1.FooterRow.FindControl("ddlyear")).SelectedValue;
SqlDataSource1.InsertParameters["RatePerHour"].DefaultValue =
((TextBox)GridView1.FooterRow.FindControl("txtrate")).Text;
SqlDataSource1.Insert();
}
catch (Exception ex)
{
}
}
protected void Button1_Click(object sender, EventArgs e)
{
}
}
我的aspx代码是：（编辑小时或每小时费率后必须更改总计算）
<%@ Page Language="C#" AutoEventWireup="true" CodeFile="ProjectBilling.aspx.cs" Inherits="ProjectBilling" %>
<!DOCTYPE html>
<html xmlns="http://www.w3.org/1999/xhtml">
<head runat="server">
<title>Project Billing</title>
<link href="StyleSheet1.css" rel="stylesheet" />
</head>
<script>
function multiplication(hour, rate, TextBoxInsertTotal) {
//Your logic for multiplication
var hour = document.getElementById(txtHour).value;
var rate = document.getElementById(txtrate).value;
document.getElementById(TextBoxInsertTotal).value = hour * rate;
}
</script>
<body>
<form id="form1" runat="server">
<div>
<div id="menu">
<ul>
<li><a href="HomePage.aspx">Home</a></li>
<li><a href="ProjectEntry.aspx">Projects</a></li>
<li><a href="ProjectBilling.aspx">Project Billing</a></li>
<li><a href="report1.aspx">Report</a></li>
<li><a href="login.aspx">Logout</a></li>
</ul>
</div>
<br />
<br />
<h2>Project Billing</h2>
<br />
<br />
<asp:GridView ID="GridView1" runat="server" align="center" AutoGenerateColumns="False" CellPadding="4" DataKeyNames="ProjectBillingId" ForeColor="#333333" GridLines="None" ShowFooter="True" DataSourceID="SqlDataSource1" AllowPaging="True" OnRowDataBound="GridView1_RowDataBound">
<AlternatingRowStyle BackColor="White" ForeColor="#284775" />
<Columns>
<asp:TemplateField HeaderText="" InsertVisible="False" SortExpression="Id">
<FooterTemplate>
<asp:Button ID="Add" runat="server" Text="Insert" OnClick="Add_Click" />
</FooterTemplate>
</asp:TemplateField>
<asp:TemplateField HeaderText="Project Type" SortExpression="Project Type">
<EditItemTemplate>
<asp:DropDownList ID="ddlNames" runat="server" DataTextField="ProjectType" DataValueField="ProjectType" DataSourceID="SqlDataSource2" SelectedValue='<%# Bind("ProjectType") %>'>
</asp:DropDownList>
</EditItemTemplate>
<ItemTemplate>
<asp:Label ID="Label4" runat="server" Text='<%# Bind("ProjectType") %>'></asp:Label>
</ItemTemplate>
<FooterTemplate>
<asp:DropDownList ID="ddlName" runat="server" DataTextField="ProjectType" DataValueField="ProjectType" DataSourceID="SqlDataSource2">
</asp:DropDownList>
</FooterTemplate>
</asp:TemplateField>
<asp:TemplateField HeaderText="Project Name" SortExpression="Project Name">
<EditItemTemplate>
<asp:TextBox ID="projectNameTextBox" runat="server" Text='<%# Bind("ProjectName") %>'>
</asp:TextBox>
</EditItemTemplate>
<ItemTemplate>
<asp:Label ID="Label3" runat="server" Text='<%# Bind("ProjectName") %>'></asp:Label>
</ItemTemplate>
<FooterTemplate>
<asp:TextBox ID="projectnameTextBox" runat="server">
</asp:TextBox>
</FooterTemplate>
</asp:TemplateField>
<asp:TemplateField HeaderText="Hour" SortExpression="Hour">
<EditItemTemplate>
<asp:TextBox ID="TextBox1" runat="server" Text='<%# Bind("Hour") %>'></asp:TextBox>
</EditItemTemplate>
<ItemTemplate>
<asp:Label ID="Label2" runat="server" Text='<%# Bind("Hour") %>'></asp:Label>
</ItemTemplate>
<FooterTemplate>
<asp:TextBox ID="txtHour" runat="server" CssClass="txthr"></asp:TextBox>
<%--<asp:RequiredFieldValidator ID="rfvFirstName" runat="server" ErrorMessage="FirstName is reqired" ControlToValidate="txtFirstName" Text="*" ForeColor="Red"></asp:RequiredFieldValidator>--%>
</FooterTemplate>
</asp:TemplateField>
<asp:TemplateField HeaderText="Rate/Hour" SortExpression="Rate/Hour">
<EditItemTemplate>
<asp:TextBox ID="ratePerHourTextBox" runat="server" Text='<%# Bind("RatePerHour") %>'></asp:TextBox>
</EditItemTemplate>
<ItemTemplate>
<asp:Label ID="hourLabel" runat="server" Text='<%# Bind("RatePerHour") %>'></asp:Label>
</ItemTemplate>
<FooterTemplate>
<asp:TextBox ID="txtrate" runat="server" ></asp:TextBox>
<%--<asp:RequiredFieldValidator ID="rfvFirstName" runat="server" ErrorMessage="FirstName is reqired" ControlToValidate="txtFirstName" Text="*" ForeColor="Red"></asp:RequiredFieldValidator>--%>
</FooterTemplate>
</asp:TemplateField>
<asp:TemplateField HeaderText="Total" SortExpression="Total">
<%--<ItemTemplate>
<asp:Label ID="totalLabel" runat="server" CssClass="total" Text='<%#DataBinder.Eval(Container.DataItem,("RatePerHour"))%>*<%#DataBinder.Eval(Container.DataItem,("Hour"))%>'></asp:Label>
</ItemTemplate>--%>
<%--<EditItemTemplate>
<asp:TextBox ID="TextBoxEditTotal" runat="server" Text='<%#CalculateTotal((double)Eval("RatePerHour"), (int)Eval("Hour")) %>'></asp:TextBox>
</EditItemTemplate>--%>
<FooterTemplate>
<asp:TextBox ID="TextBoxInsertTotal" runat="server" ></asp:TextBox>
</FooterTemplate>
</asp:TemplateField>
<asp:TemplateField HeaderText="Year" SortExpression="Year">
<EditItemTemplate>
<asp:DropDownList ID="DropDownList3" runat="server" SelectedValue='<%# Bind("Year") %>'>
<asp:ListItem Value="-1">Year:</asp:ListItem>
<asp:ListItem Value="2017">2017</asp:ListItem>
<asp:ListItem Value="2016">2016</asp:ListItem>
<asp:ListItem Value="2015">2015</asp:ListItem>
<asp:ListItem Value="2014">2014</asp:ListItem>
<asp:ListItem Value="2013">2013</asp:ListItem>
<asp:ListItem Value="2012">2012</asp:ListItem>
<asp:ListItem Value="2011">2011</asp:ListItem>
<asp:ListItem Value="2010">2010</asp:ListItem>
<asp:ListItem Value="2009">2009</asp:ListItem>
</asp:DropDownList>
<%--<asp:RequiredFieldValidator ID="rfvEditYear" runat="server" ErrorMessage="Year is reqired" ControlToValidate="DropDownList3" Text="*" ForeColor="Red" InitialValue="Year:"></asp:RequiredFieldValidator>--%>
</EditItemTemplate>
<ItemTemplate>
<asp:Label ID="Label9" runat="server" Text='<%# Bind("Year") %>'></asp:Label>
</ItemTemplate>
<FooterTemplate>
<asp:DropDownList ID="ddlyear" runat="server">
<asp:ListItem Value="-1">Year:</asp:ListItem>
<asp:ListItem Value="2017">2017</asp:ListItem>
<asp:ListItem Value="2016">2016</asp:ListItem>
<asp:ListItem Value="2015">2015</asp:ListItem>
<asp:ListItem Value="2014">2014</asp:ListItem>
<asp:ListItem Value="2013">2013</asp:ListItem>
<asp:ListItem Value="2012">2012</asp:ListItem>
<asp:ListItem Value="2011">2011</asp:ListItem>
<asp:ListItem Value="2010">2010</asp:ListItem>
<asp:ListItem Value="2009">2009</asp:ListItem>
</asp:DropDownList>
<%--<asp:RequiredFieldValidator ID="rfvYear" runat="server" ErrorMessage="Year is reqired" ControlToValidate="ddlyear" Text="*" ForeColor="Red" InitialValue="Day:"></asp:RequiredFieldValidator>--%>
</FooterTemplate>
</asp:TemplateField>
<asp:TemplateField HeaderText="Month" SortExpression="Month">
<EditItemTemplate>
<asp:DropDownList ID="DropDownList2" runat="server" SelectedValue='<%# Bind("Month") %>'>
<asp:ListItem Value="-1">Month:</asp:ListItem>
<asp:ListItem Value="January">January</asp:ListItem>
<asp:ListItem Value="February">February</asp:ListItem>
<asp:ListItem Value="March">March</asp:ListItem>
<asp:ListItem Value="April">April</asp:ListItem>
<asp:ListItem Value="May">May</asp:ListItem>
<asp:ListItem Value="June">June</asp:ListItem>
<asp:ListItem Value="July">July</asp:ListItem>
<asp:ListItem Value="August">August</asp:ListItem>
<asp:ListItem Value="September">September</asp:ListItem>
<asp:ListItem Value="October">October</asp:ListItem>
<asp:ListItem Value="November">November</asp:ListItem>
<asp:ListItem Value="December">December</asp:ListItem>
</asp:DropDownList>
<%--<asp:RequiredFieldValidator ID="rfvEditMonth" runat="server" ErrorMessage="Month is reqired" ControlToValidate="DropDownList2" Text="*" ForeColor="Red" InitialValue="Month:"></asp:RequiredFieldValidator>--%>
</EditItemTemplate>
<ItemTemplate>
<asp:Label ID="Label8" runat="server" Text='<%# Bind("Month") %>'></asp:Label>
</ItemTemplate>
<FooterTemplate>
<asp:DropDownList ID="ddlmonth" runat="server">
<asp:ListItem Value="-1">Month:</asp:ListItem>
<asp:ListItem Value="January">January</asp:ListItem>
<asp:ListItem Value="February">February</asp:ListItem>
<asp:ListItem Value="March">March</asp:ListItem>
<asp:ListItem Value="April">April</asp:ListItem>
<asp:ListItem Value="May">May</asp:ListItem>
<asp:ListItem Value="June">June</asp:ListItem>
<asp:ListItem Value="July">July</asp:ListItem>
<asp:ListItem Value="August">August</asp:ListItem>
<asp:ListItem Value="September">September</asp:ListItem>
<asp:ListItem Value="October">October</asp:ListItem>
<asp:ListItem Value="November">November</asp:ListItem>
<asp:ListItem Value="December">December</asp:ListItem>
</asp:DropDownList>
<%--<asp:RequiredFieldValidator ID="rfvMonth" runat="server" ErrorMessage="Month is reqired" ControlToValidate="ddlmonth" Text="*" ForeColor="Red" InitialValue="Month:"></asp:RequiredFieldValidator>--%>
</FooterTemplate>
</asp:TemplateField>
<asp:TemplateField ShowHeader="False">
<EditItemTemplate>
<asp:LinkButton ID="LinkButton1" runat="server" CausesValidation="True" CommandName="Update" Text="Update"></asp:LinkButton>
<asp:LinkButton ID="LinkButton2" runat="server" CausesValidation="False" CommandName="Cancel" Text="Cancel"></asp:LinkButton>
</EditItemTemplate>
<ItemTemplate>
<asp:LinkButton ID="LinkButton1" runat="server" CausesValidation="False" CommandName="Edit" Text="Edit"></asp:LinkButton>
<asp:LinkButton ID="LinkButton2" runat="server" CausesValidation="False" CommandName="Delete" Text="Delete"></asp:LinkButton>
</ItemTemplate>
</asp:TemplateField>
</Columns>
<EditRowStyle BackColor="#999999" />
<FooterStyle BackColor="#5D7B9D" Font-Bold="True" ForeColor="White" />
<HeaderStyle BackColor="#5D7B9D" Font-Bold="True" ForeColor="White" />
<PagerStyle BackColor="#284775" ForeColor="White" HorizontalAlign="Center" />
<RowStyle BackColor="#F7F6F3" ForeColor="#333333" HorizontalAlign="Center" />
<SelectedRowStyle BackColor="#E2DED6" Font-Bold="True" ForeColor="#333333" />
<SortedAscendingCellStyle BackColor="#E9E7E2" />
<SortedAscendingHeaderStyle BackColor="#506C8C" />
<SortedDescendingCellStyle BackColor="#FFFDF8" />
<SortedDescendingHeaderStyle BackColor="#6F8DAE" />
</asp:GridView>
<asp:SqlDataSource ID="SqlDataSource2" runat="server" ConnectionString="<%$ConnectionStrings:ProjectManagementConnectionString%>" SelectCommand="SELECT * from Project"></asp:SqlDataSource>
<asp:SqlDataSource ID="SqlDataSource1" runat="server" ConnectionString="<%$ ConnectionStrings:ProjectManagementConnectionString %>" DeleteCommand="DELETE FROM [ProjectBilling] WHERE [ProjectBillingId] = @ProjectBillingId" InsertCommand="INSERT INTO [ProjectBilling] ([Hour],[RatePerHour], [ProjectType],[ProjectName], [Month], [Year]) VALUES (@Hour,@RatePerHour, @ProjectType,@ProjectName, @Month, @Year)" SelectCommand="SELECT * FROM [ProjectBilling]" UpdateCommand="UPDATE [ProjectBilling] SET [Hour] = @Hour,[RatePerHour]=@RatePerHour, [ProjectType] = @ProjectType,[ProjectName] = @ProjectName, [Month] = @Month, [Year] = @Year WHERE [ProjectBillingId] = @ProjectBillingId">
<DeleteParameters>
<asp:Parameter Name="ProjectBillingId" Type="Int32" />
</DeleteParameters>
<InsertParameters>
<asp:Parameter Name="Hour" Type="String" />
<asp:Parameter Name="RatePerHour" Type="Double" />
<asp:Parameter Name="ProjectType" Type="String" />
<asp:Parameter Name="ProjectName" Type="String" />
<asp:Parameter Name="Month" Type="String" />
<asp:Parameter Name="Year" Type="String" />
</InsertParameters>
<UpdateParameters>
<asp:Parameter Name="Hour" Type="String" />
<asp:Parameter Name="RatePerHour" Type="Double" />
<asp:Parameter Name="ProjectType" Type="String" />
<asp:Parameter Name="ProjectName" Type="String" />
<asp:Parameter Name="Month" Type="String" />
<asp:Parameter Name="Year" Type="String" />
<asp:Parameter Name="ProjectBillingId" Type="Int32" />
</UpdateParameters>
</asp:SqlDataSource>
<br />
</div>
</form>
我已经在我的代码中尝试了几个JavaScript选项。没有一个有效..示例代码将不胜感激。
此处的问题与 aspx 页中的控件 ID 有关。例如，在 asp 网格视图行中有以下文本框：
<asp:TextBox ID="TextBox1" runat="server" Text='<%# Bind("Hour") %>'></asp:TextBox>
此处的文本框 ID 是"TextBox1"，但在您后面的代码中搜索 ID 为"小时"的文本框
TextBox txtHour = (TextBox)e.Row.FindControl("Hour");
我认为您将文本框 ID 误认为是 asp：模板字段标头属性
<asp:TemplateField HeaderText="Hour" SortExpression="Hour">
确保在代码隐藏中搜索时使用的 ID（使用 FindControl）与 aspx 页中的控件 ID 相同（此处为文本框控件 ID）
由于代码隐藏中的 FindControl 方法（在 RowDataBound 事件中）无法找到 ID 为"小时"的文本框控件，因此会引发错误"空引用异常"
网格行中的其他控件也是如此。
已引用的答案
protected void GridView1_RowDataBound(object sender, GridViewRowEventArgs e)
{
if (e.Row.RowType == DataControlRowType.Footer)
{
TextBox txtHour = (TextBox)e.Row.FindControl("txtHour");
TextBox txtrate = (TextBox)e.Row.FindControl("ratePerHourTextBox");
TextBox TextBoxInsertTotal = (TextBox)e.Row.FindControl("TextBoxInsertTotal");
txtHour.Attributes["onKeyup"] = "javascript: return multiplication('" + Convert.ToInt32(txtHour.Text) + "','" + Convert.ToDouble(txtrate.Text) + "','" + Convert.ToInt32(TextBoxInsertTotal.ClientID) + "')";
txtrate.Attributes["onKeyup"] = "javascript: return multiplication('" + Convert.ToInt32(txtHour.Text) + "','" + Convert.ToDouble(txtrate.Text) + "','" + Convert.ToInt32(TextBoxInsertTotal.ClientID) + "')";
}
}
当您尝试查找一个（或多个控件）时，您应该使用 ID
TextBox txtHour = (TextBox)e.Row.FindControl("Hour");
您正在尝试查找 ID 为"小时"的控件。这是不存在的。它位于名为"文本框1"的代码中
This line:
<asp:TextBox ID="TextBox1" runat="server" Text='<%# Bind("Hour")%>'>
Should be changed to this:
<asp:TextBox ID="Hour" runat="server" Text='<%# Bind("Hour")%>'>
尝试使用正确的 ID 找到它 - 在本例中为"TextBox1"
在我看来，您的网格中不存在这些控件：
TextBox txtHour = (TextBox)e.Row.FindControl("Hour");
TextBox txtrate = (TextBox)e.Row.FindControl("RatePerHour");
TextBox TextBoxInsertTotal = (TextBox)e.Row.FindControl("Total");
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