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添加 3 个标签控件的值以在另一个标签控件中输出结果时出错

[英]Error with adding values of 3 label controls to output result in another label control

 原文  2021-07-17 19:54:24  3   1    c#/ html

问题描述

这是我想要实现的目标的完整描述。

我设计它的方式是我有

  • 3 复选框
  • 3 下拉控件：数量
  • 7 个标签控件：3 个单价标签、3 个小计标签和一个 GrandTotal 标签

在页面加载时，DropDown 将被禁用，单价标签的值分别为“100”、“200”和“100”，3 个小计标签的初始值为“0”，GrandTotal 标签将为“0” .

当用户单击任何一个复选框时，将启用附加到该单击复选框的下拉列表，当用户从下拉列表中选择数量时，单价标签的值将乘以数量下拉列表中的值，并在 SubTotal 中输出结果标签。

最后，将SubTotal Labels 的所有值相加，结果将显示在GrandTotal Label 中。

这是视图的样子

Product        Unit Price       Quantity     SubTotal      GrandTotal

Product1          100              3            300

Product2          200              1            200

Product3          100              2            200          
                                                               700

这是我的代码（请原谅我显示代码的方式。我尝试上传我的代码但它没有进入代码窗口，因为我正在使用移动设备提出这个问题）

protected void Page_Load(object sender, EventArgs e)
{
    unitprice1.Text = ("100").ToString();
    unitprice2.Text = ("200").ToString();
    unitprice3.Text = ("100").ToString();
}

protected void CheckBox1_CheckedChanged(object sender, EventArgs e) 
{
    Product1DropDown.Enabled = CheckBox1.Checked;
    Subtotal1.Text = ("0").ToString();
}

protected void CheckBox2_CheckedChanged(object sender, EventArgs e)
{
    Product2DropDown.Enabled = CheckBox2.Checked;
    Subtotal2.Text = ("0").ToString();
}

protected void CheckBox3_CheckedChanged(object sender, EventArgs e)
{
    Product3DropDown.Enabled = CheckBox3.Checked;
    Subtotal3.Text = ("0").ToString();
}

protected void Product1DropDown_SelectedIndexChanged(object sender, EventArgs e)
{
    if (Product1DropDown.SelectedIndex > 0)
    {
        Qty1.Text = Product1DropDown.SelectedItem.Text;
        Subtotal1.Text = Convert.ToString(Convert.ToInt32(Qty1.Text) * Convert.ToInt32(unitprice1.Text)).ToString();
    }
}

protected void Product2DropDown_SelectedIndexChanged(object sender, EventArgs e)
{
    if (Product2DropDown.SelectedIndex > 0)
    {
        Qty2.Text = Product2DropDown.SelectedItem.Text;
        Subtotal2.Text = Convert.ToString(Convert.ToInt32(Qty2.Text) * Convert.ToInt32(unitprice2.Text)).ToString();
    }
}

protected void Product3DropDown_SelectedIndexChanged(object sender, EventArgs e)
{
    if(Product3DropDown.SelectedIndex > 0)
    {
        Qty3.Text = Product3DropDown.SelectedItem.Text;Subtotal3.Text = Convert.ToString(Convert.ToInt32(Qty3.Text) * Convert.ToInt32(unitprice3.Text)).ToString();
    }
}

1 个解决方案

解决方案1
 0  2021-07-17 23:31:15

确保您已为每个CheckBox包含AutoPostBack="true" ：

<asp:CheckBox ID="checkBox1" runat="server" Checked="false" OnCheckedChanged="checkBox1_CheckedChanged" AutoPostBack="true" />

以及每个DropDownList ：

<asp:DropDownList id="product1DropDown" runat="server" OnSelectedIndexChanged="product1DropDown_SelectedIndexChanged" AutoPostBack="true" Enabled="false" style="align-content:center;width: 75px" />

创建一个方法来计算小计。 由于我们必须计算 3 种不同产品的小计，因此我们将创建一个方法。 参数将是 DropDownList 中的数量和标签中的单价。

private decimal CalculateSubtotal(string strQty, string strUnitPrice)
{
    int qty = 0;
    decimal unitPrice = 0m;
    decimal subtotal = 0m;

    //clear msg
    lblMsg.Text = string.Empty;

    if (!String.IsNullOrEmpty(strQty))
    {
        //try to convert
        Int32.TryParse(strQty, out qty);
    }
    else
    {
        throw new Exception("Error: Qty is null or empty");
    }

    if (!String.IsNullOrEmpty(strUnitPrice))
    {
        //try to convert
        Decimal.TryParse(strUnitPrice, out unitPrice);

        //calculate
        subtotal = qty * unitPrice;
    }
    else
    {
        throw new Exception("Error: UnitPrice is null or empty");
    }
    
    return subtotal;
}

接下来，创建一个计算总计的方法。 此方法将为每个产品调用CalculateSubtotal 。

计算GrandTotal

private void CalculateGrandTotal()
{
    decimal subtotal1 = 0m; //use 'm' for decimal
    decimal subtotal2 = 0m; //use 'm' for decimal
    decimal subtotal3 = 0m; //use 'm' for decimal

    //calculate subtotal1 - only calculate if CheckBox is enabled
    if (checkBox1.Enabled && !String.IsNullOrEmpty(product1DropDown.Text))
    {
        //calculate subtotal
        subtotal1 = CalculateSubtotal(product1DropDown.Text, lblProduct1UnitPrice.Text);
    }

    //set value
    lblProduct1Subtotal.Text = subtotal1.ToString("$###,##0.00");

    //calculate subtotal 2 - only calculate if CheckBox is enabled
    if (checkBox2.Enabled && !String.IsNullOrEmpty(product2DropDown.Text))
    {
        //calculate subtotal
        subtotal2 = CalculateSubtotal(product2DropDown.Text, lblProduct2UnitPrice.Text);
    }

    //set value
    lblProduct2Subtotal.Text = subtotal2.ToString("$###,##0.00");

    //calculate subtotal3 - only calculate if CheckBox is enabled
    if (checkBox3.Enabled && !String.IsNullOrEmpty(product3DropDown.Text))
    {
        //calculate subtotal
        subtotal3 = CalculateSubtotal(product3DropDown.Text, lblProduct3UnitPrice.Text);
    }

    //set value
    lblProduct3Subtotal.Text = subtotal3.ToString("$###,##0.00");

    //calculate
    decimal grandTotal = subtotal1 + subtotal2 + subtotal3;

    //set value
    lblGrandTotal.Text = grandTotal.ToString("$###,##0.00");
}

在每个 CheckBox CheckChanged事件处理程序中，我们不仅需要判断是否启用下拉，还需要重新计算总计。 如果复选框被禁用，我还决定将数量和小计重置为 0。

例如：

protected void checkBox1_CheckedChanged(object sender, EventArgs e)
{
    ////uncomment for debugging
    //lblMsg.Text = "Info: checkBox1.Checked: " + checkBox1.Checked.ToString();
    //System.Diagnostics.Debug.WriteLine("Info: checkBox1.Checked: " + checkBox1.Checked.ToString());

    //set value
    product1DropDown.Enabled = checkBox1.Checked;

    if (!product1DropDown.Enabled)
    {
        //not enabled - reset values
        product1DropDown.Text = string.Empty;
        lblProduct1Subtotal.Text = "$0.00";
    }

    //calculate
    CalculateGrandTotal();
}

由于每次更改数量时都需要重新计算总计以及该特定产品的小计，因此我们只需调用CalculateGrandTotal(); .

例如：

protected void product1DropDown_SelectedIndexChanged(object sender, EventArgs e)
{
    CalculateGrandTotal();
}

这是完整的解决方案 - 它已经过测试：

VS 2019 ：

创建新的ASP.NET Web 应用程序 (.NET Framework)

  • 项目名称： BMICalc
  • 点击创建
  • 点击清空
  • 点击创建

添加网页表单

  • 在 VS 菜单中，单击项目
  • 选择Web 表单（名称：default.aspx）

默认.aspx ：

<%@ Page Language="C#" AutoEventWireup="true" CodeBehind="default.aspx.cs" Inherits="TestAspNetDU._default" %>

<!DOCTYPE html>

<html xmlns="http://www.w3.org/1999/xhtml">
<head runat="server">
    <title></title>
</head>
<body>
    <form id="form1" runat="server">

        <div style="top: 10px; left: 150px; position: absolute;">

            <asp:Table ID="tbl1" BorderStyle="none" Border="0px" CellPadding="2" CellSpacing="0" runat="server" Width="410">
                <asp:TableHeaderRow ID="tbl1HeaderRow">
                    <asp:TableHeaderCell ID="tbl1CheckBoxHeading" Text="" style="text-align:center" />
                    <asp:TableHeaderCell ID="tbl1ProductHeading" Text="Product" style="text-align:center" />
                    <asp:TableHeaderCell ID="tbl1UnitPriceHeading" Text="Unit Price" style="text-align:center" />
                    <asp:TableHeaderCell ID="tbl1QuantityHeading" Text="Quantity" style="text-align:center" />
                    <asp:TableHeaderCell ID="tbl1SubtotalHeading" Text="Subtotal" style="text-align:center" />
                </asp:TableHeaderRow>
                
                <asp:TableRow ID="tbl1Row1">
                    <asp:TableCell Width="35px" style="align-content:center;text-align:center;vertical-align:middle">
                        <asp:CheckBox ID="checkBox1" runat="server" Checked="false" OnCheckedChanged="checkBox1_CheckedChanged" AutoPostBack="true" />
                    </asp:TableCell>

                    <asp:TableCell Width="100px" style="text-align:left">
                        <asp:Label id="lblProduct1Name" runat="server" Text="Product1" style="text-align:left" />
                    </asp:TableCell>

                    <asp:TableCell Width="75px" style="align-content:center;text-align:center">
                        <asp:Label id="lblProduct1UnitPrice" runat="server" Text="100" />
                    </asp:TableCell>

                    <asp:TableCell Width="100px" style="align-content:center;text-align:center">
                        <asp:DropDownList id="product1DropDown" runat="server" OnSelectedIndexChanged="product1DropDown_SelectedIndexChanged" AutoPostBack="true" Enabled="false" style="align-content:center;width: 75px" />
                    </asp:TableCell>

                    <asp:TableCell Width="100px" style="text-align:right">
                        <asp:Label id="lblProduct1Subtotal" runat="server" Text="0.00" />
                    </asp:TableCell>
                </asp:TableRow>

               
                <asp:TableRow ID="tbl1Row2">
                    <asp:TableCell Width="35px" style="align-content:center;text-align:center;vertical-align:middle">
                        <asp:CheckBox ID="checkBox2" runat="server" Checked="false" OnCheckedChanged="checkBox2_CheckedChanged" AutoPostBack="true" />
                    </asp:TableCell>

                    <asp:TableCell Width="100px" style="text-align:left">
                        <asp:Label id="lblProduct2Name" runat="server" Text="Product2" style="text-align:left" />
                    </asp:TableCell>

                    <asp:TableCell Width="75px" style="align-content:center;text-align:center">
                        <asp:Label id="lblProduct2UnitPrice" runat="server" Text="200" style="text-align:center" />
                    </asp:TableCell>

                    <asp:TableCell Width="100" style="align-content:center;text-align:center">
                        <asp:DropDownList id="product2DropDown" runat="server" OnSelectedIndexChanged="product2DropDown_SelectedIndexChanged" AutoPostBack="true" Enabled="false" style="align-content:center;width: 75px" />
                    </asp:TableCell>

                    <asp:TableCell Width="100px" style="text-align:right">
                        <asp:Label id="lblProduct2Subtotal" runat="server" Text="0.00" />
                    </asp:TableCell>
                </asp:TableRow>

               
                <asp:TableRow ID="tbl1Row3">
                    <asp:TableCell Width="35px" style="align-content:center;text-align:center;vertical-align:middle">
                        <asp:CheckBox ID="checkBox3" runat="server" Checked="false" OnCheckedChanged="checkBox3_CheckedChanged" AutoPostBack="true" />
                    </asp:TableCell>

                    <asp:TableCell Width="100px" style="text-align:left">
                        <asp:Label id="lblProduct3Name" runat="server" Text="Product3" style="text-align:left" />
                    </asp:TableCell>

                    <asp:TableCell Width="75px" style="align-content:center;text-align:center">
                        <asp:Label id="lblProduct3UnitPrice" runat="server" Text="100" style="text-align:center" />
                    </asp:TableCell>

                    <asp:TableCell Width="100" style="align-content:center;text-align:center">
                        <asp:DropDownList id="product3DropDown" runat="server" OnSelectedIndexChanged="product3DropDown_SelectedIndexChanged" AutoPostBack="true" Enabled="false" style="align-content:center;width: 75px" />
                    </asp:TableCell>

                    <asp:TableCell Width="100px" style="text-align:right">
                        <asp:Label id="lblProduct3Subtotal" runat="server" Text="0.00" />
                    </asp:TableCell>
                </asp:TableRow>
            </asp:Table>
        </div>

        <div style="top: 120px; left: 150px; position: absolute">
            <asp:Table ID="tbl1GrandTotal" BorderStyle="none" Border="0px" CellPadding="0" CellSpacing="0" runat="server" Width="410">
                <asp:TableRow ID="tbl1GrandTotalRow">
                    <asp:TableCell Width="160px" style="align-content:center;text-align:center;vertical-align:middle"></asp:TableCell>

                    <asp:TableCell Width="125px" style="font-weight:bold; text-align:center">
                        <asp:Label id="lblGrandTotalHeading" runat="server" Text="Grand Total:" />
                    </asp:TableCell>

                    <asp:TableCell Width="100px" style="font-weight:bold; text-align:right">
                        <asp:Label id="lblGrandTotal" runat="server" Text="0.00" />
                    </asp:TableCell>
                </asp:TableRow>
            </asp:Table>
        </div>

        <div style="top: 625px; left: 150px; position: absolute">
            <span style="color:red">
                <asp:Label ID="lblMsg" runat="server" Text="" />
            </span>
        </div>
    </form>
</body>
</html>

默认.aspx.cs

using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.Web.UI;
using System.Web.UI.WebControls;

namespace TestAspNetDU
{
    public partial class _default : System.Web.UI.Page
    {
        protected void Page_Load(object sender, EventArgs e)
        {
            //set values
          
            lblProduct1UnitPrice.Text = "100";
            lblProduct2UnitPrice.Text = "200";
            lblProduct3UnitPrice.Text = "100";

            //populate DropDownList
            for(int i = 0; i < 100; i++)
            {
                if (i > 0)
                {
                    //add
             
                    product1DropDown.Items.Add(i.ToString());
                    product2DropDown.Items.Add(i.ToString());
                    product3DropDown.Items.Add(i.ToString());
                }
                else
                {
                    //add - for 0, show empty (blank)
                    product1DropDown.Items.Add("");
                    product2DropDown.Items.Add("");
                    product3DropDown.Items.Add("");
                }
            }
        }

        private void CalculateGrandTotal()
        {
            decimal subtotal1 = 0m; //use 'm' for decimal
            decimal subtotal2 = 0m; //use 'm' for decimal
            decimal subtotal3 = 0m; //use 'm' for decimal

            try
            {
                //calculate subtotal1 - only calculate if CheckBox is enabled
                if (checkBox1.Enabled && !String.IsNullOrEmpty(product1DropDown.Text))
                {
                    //calculate subtotal
                    subtotal1 = CalculateSubtotal(product1DropDown.Text, lblProduct1UnitPrice.Text);
                }

                //set value
                lblProduct1Subtotal.Text = subtotal1.ToString("$###,##0.00");
            }
            catch(Exception ex)
            {
                //ToDo: log msg

                //set value
                lblMsg.Text = "Error (CalculateGrandTotal 1) - " + ex.Message;

                //uncommenting the following line may be useful for debugging
                //throw ex;
            }

            try
            {
                //calculate subtotal 2 - only calculate if CheckBox is enabled
                if (checkBox2.Enabled && !String.IsNullOrEmpty(product2DropDown.Text))
                {
                    //calculate subtotal
                    subtotal2 = CalculateSubtotal(product2DropDown.Text, lblProduct2UnitPrice.Text);
                }

                //set value
                lblProduct2Subtotal.Text = subtotal2.ToString("$###,##0.00");
            }
            catch(Exception ex)
            {
                //ToDo: log msg

                //set value
                lblMsg.Text = "Error (CalculateGrandTotal 2) - " + ex.Message;

                //uncommenting the following line may be useful for debugging
                //throw ex;
            }

            try
            {
                //calculate subtotal3 - only calculate if CheckBox is enabled
                if (checkBox3.Enabled && !String.IsNullOrEmpty(product3DropDown.Text))
                {
                    //calculate subtotal
                    subtotal3 = CalculateSubtotal(product3DropDown.Text, lblProduct3UnitPrice.Text);
                }

                //set value
                lblProduct3Subtotal.Text = subtotal3.ToString("$###,##0.00");
            }
            catch(Exception ex)
            {
                //ToDo: log msg

                //set value
                lblMsg.Text = "Error (product3DropDown_SelectedIndexChanged) - " + ex.Message;

                //uncommenting the following line may be useful for debugging
                //throw ex;
            }

            //calculate
            decimal grandTotal = subtotal1 + subtotal2 + subtotal3;

            //set value
            lblGrandTotal.Text = grandTotal.ToString("$###,##0.00");
        }

        private decimal CalculateSubtotal(string strQty, string strUnitPrice)
        {
            int qty = 0;
            decimal unitPrice = 0m;
            decimal subtotal = 0m;

            //clear msg
            lblMsg.Text = string.Empty;

            if (!String.IsNullOrEmpty(strQty))
            {
                //try to convert
                Int32.TryParse(strQty, out qty);
            }
            else
            {
                throw new Exception("Error: Qty is null or empty");
            }

            if (!String.IsNullOrEmpty(strUnitPrice))
            {
                //try to convert
                Decimal.TryParse(strUnitPrice, out unitPrice);

                //calculate
                subtotal = qty * unitPrice;
            }
            else
            {
                throw new Exception("Error: UnitPrice is null or empty");
            }
            
            return subtotal;
        }

        protected void checkBox1_CheckedChanged(object sender, EventArgs e)
        {
            ////uncomment for debugging
            //lblMsg.Text = "Info: checkBox1.Checked: " + checkBox1.Checked.ToString();
            //System.Diagnostics.Debug.WriteLine("Info: checkBox1.Checked: " + checkBox1.Checked.ToString());

            //set value
            product1DropDown.Enabled = checkBox1.Checked;

            if (!product1DropDown.Enabled)
            {
                //not enabled - reset values
                product1DropDown.Text = string.Empty;
                lblProduct1Subtotal.Text = "$0.00";
            }

            //calculate
            CalculateGrandTotal();
        }

        protected void checkBox2_CheckedChanged(object sender, EventArgs e)
        {
            //uncomment for debugging
            //lblMsg.Text = "Info: checkBox2.Checked: " + checkBox2.Checked.ToString();

            //set value
            product2DropDown.Enabled = checkBox2.Checked;

            if (!product2DropDown.Enabled)
            {
                //not enabled - reset values
                product2DropDown.Text = string.Empty;
                lblProduct2Subtotal.Text = "$0.00";
            }

            //calculate
            CalculateGrandTotal();
        }

        protected void checkBox3_CheckedChanged(object sender, EventArgs e)
        {
            //uncomment for debugging
            //lblMsg.Text = "Info: checkBox3.Checked: " + checkBox3.Checked.ToString();

            //set value
            product3DropDown.Enabled = checkBox3.Checked;

            if (!product3DropDown.Enabled)
            {
                //not enabled - reset values
                product3DropDown.Text = string.Empty;
                lblProduct3Subtotal.Text = "$0.00";
            }

            //calculate
            CalculateGrandTotal();
        }

        protected void product1DropDown_SelectedIndexChanged(object sender, EventArgs e)
        {
            CalculateGrandTotal();
        }

        protected void product2DropDown_SelectedIndexChanged(object sender, EventArgs e)
        {
            CalculateGrandTotal();
        }

        protected void product3DropDown_SelectedIndexChanged(object sender, EventArgs e)
        {
            CalculateGrandTotal();
        }
    }
}

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