如何在Razor Index页面表格中计算筛选列的总计值

我正在用Index.cshtml创建可用户筛选的报表，当前报表功能正常，表格页脚的总计值能正常显示。但第二个总计值需要只计算DISPFinePdInFull为"Yes"的DISPFineAmount总和，尝试的写法都报错，求指导。

现有代码 #

Index.cshtml相关代码 #

<tbody>
    @foreach (var obj in Model.Results)
    {
        <tr>
            <td width="5%" align="left">@obj.CRTCourt</td>
            <td width="5%" align="left">@obj.PILastName, @obj.PIFirstName @obj.PIMiddleInitial</td>
            <td width="10%">@obj.ArrestDate</td>
            <td width="10%">@obj.DISPConvictionDate</td>
            <td width="15%" align="left">@obj.ArrestOfficer</td>
            <td width="10%">@obj.DISPFineAmount</td>
            <td width="10%">@obj.DISPDueDate</td>
            <td width="5%" align="left">@obj.DISPFinePdInFull</td>
            <td width="5%" id="FilteredFine">
            @if (@obj.DISPFinePdInFull == "Yes") 
            {
                @obj.DISPFineAmount
            }
            else
            {
                <text>""</text>
            }
            </td>
        </tr>
    }
</tbody>
<tfoot>
    <tr>
        <td></td>
        <td></td>
        <td></td>
        <td></td>
        <td>
            Total Fines Assessed 
        </td>
        <td>
            @Model.Results.Sum(i=>i.DISPFineAmount)
        </td>
        <td></td>
        <td>
            Total Pd
        </td>
        <td>
            <!-- (This part is the area I am struggling with. 
                 Think I need to add something to my .cs to handle this, 
                 but not sure what?)
            @if (Model.Results.DISPFinePdInFull == "Yes")
            {
                @Model.Results.Sum(i => i.DISPFineAmount)
            }
            else
            {
                <text>""</text>
            }
            -->
        </td>
    </tr>
</tfoot>
</table>

Index.cs相关代码 #

using DWITracker.Data;
using DWITracker.Model;
using Microsoft.AspNetCore.Mvc.RazorPages;
using System.Data;

namespace DWITracker.Pages.Reports.CourtFines;

public class IndexModel : PageModel
{
    private readonly ApplicationDbContext _db;

    public IndexModel(ApplicationDbContext db)
    {
        _db = db;
    }

    public IEnumerable<Incident> Results { get; set; }

    public string CourtSort { get; set; }

    public void OnGet()
    {
        Results = _db.Incident.ToList();
    }

    public void OnPost(DateTime startdate, DateTime enddate, string sortOrder)
    {
        Results = (from x in _db.Incident where (x.DISPConvictionDate >= startdate) && (x.DISPConvictionDate <= enddate) select x).ToList();

        CourtSort = sortOrder == "Court_Asc_Sort" ? "Court_Desc_Sort" : "Court_Asc_Sort";

        switch (sortOrder)
        {
            case "Court_Asc_Sort":
                Results = Results.OrderBy(s => s.CRTCourt).ThenBy(s => s.PILastName);
                break;
            case "Court_Desc_Sort":
                Results = Results.OrderByDescending(s => s.CRTCourt).ThenByDescending(s => s.PILastName);
                break;
            default:
                Results = Results.OrderBy(s => s.CRTCourt).ThenBy(s => s.PILastName);
                break;
        }
    }

}

解决方法 #

方法1：直接在视图中实现条件求和 #

你之前的错误是直接访问集合Model.Results的DISPFinePdInFull属性，这是不对的——集合本身没有这个属性，需要先筛选出符合条件的元素再求和。把tfoot里的注释代码替换成：

<td>
    @Model.Results.Where(i => i.DISPFinePdInFull == "Yes").Sum(i => i.DISPFineAmount)
</td>

如果没有符合条件的记录，Sum会返回0，若想显示空字符串，可加判断：

<td>
    @{
        var totalPaid = Model.Results.Where(i => i.DISPFinePdInFull == "Yes").Sum(i => i.DISPFineAmount);
        @(totalPaid > 0 ? totalPaid.ToString() : "")
    }
</td>

方法2：在PageModel中计算（推荐） #

把计算逻辑移到后端，视图只负责展示，代码更清晰且便于维护。修改IndexModel：

using DWITracker.Data;
using DWITracker.Model;
using Microsoft.AspNetCore.Mvc.RazorPages;
using System.Data;

namespace DWITracker.Pages.Reports.CourtFines;

public class IndexModel : PageModel
{
    private readonly ApplicationDbContext _db;

    public IndexModel(ApplicationDbContext db)
    {
        _db = db;
    }

    public IEnumerable<Incident> Results { get; set; }
    public decimal TotalFinesAssessed { get; set; }
    public decimal TotalPaidFines { get; set; }
    public string CourtSort { get; set; }

    public void OnGet()
    {
        Results = _db.Incident.ToList();
        CalculateTotals();
    }

    public void OnPost(DateTime startdate, DateTime enddate, string sortOrder)
    {
        Results = (from x in _db.Incident where (x.DISPConvictionDate >= startdate) && (x.DISPConvictionDate <= enddate) select x).ToList();

        CourtSort = sortOrder == "Court_Asc_Sort" ? "Court_Desc_Sort" : "Court_Asc_Sort";

        switch (sortOrder)
        {
            case "Court_Asc_Sort":
                Results = Results.OrderBy(s => s.CRTCourt).ThenBy(s => s.PILastName);
                break;
            case "Court_Desc_Sort":
                Results = Results.OrderByDescending(s => s.CRTCourt).ThenByDescending(s => s.PILastName);
                break;
            default:
                Results = Results.OrderBy(s => s.CRTCourt).ThenBy(s => s.PILastName);
                break;
        }
        CalculateTotals();
    }

    private void CalculateTotals()
    {
        TotalFinesAssessed = Results.Sum(i => i.DISPFineAmount);
        TotalPaidFines = Results.Where(i => i.DISPFinePdInFull == "Yes").Sum(i => i.DISPFineAmount);
    }
}

然后在视图的tfoot里直接调用属性：

<tfoot>
    <tr>
        <td></td>
        <td></td>
        <td></td>
        <td></td>
        <td>
            Total Fines Assessed 
        </td>
        <td>
            @Model.TotalFinesAssessed
        </td>
        <td></td>
        <td>
            Total Pd
        </td>
        <td>
            @Model.TotalPaidFines
        </td>
    </tr>
</tfoot>

内容的提问来源于stack exchange，提问作者MelB