使用pivot的动态linq筛选子项

public class Sale
{
    public DateTime Date { get; set; }
    public string Product { get; set; }
    public decimal Amount { get; set; }
}

var sales = new List<Sale>
{
    new Sale { Date = new DateTime(2023, 1, 1), Product = "A", Amount = 100 },
    new Sale { Date = new DateTime(2023, 1, 1), Product = "B", Amount = 200 },
    new Sale { Date = new DateTime(2023, 1, 2), Product = "A", Amount = 150 },
    new Sale { Date = new DateTime(2023, 1, 2), Product = "B", Amount = 250 }
};

using System;
using System.Collections.Generic;
using System.Linq;
using System.Linq.Dynamic.Core;

public class PivotResult
{
    public DateTime Date { get; set; }
    public decimal A { get; set; }
    public decimal B { get; set; }
}

public static List<PivotResult> PivotSales(List<Sale> sales)
{
    var distinctDates = sales.Select(s => s.Date).Distinct().ToList();
    var distinctProducts = sales.Select(s => s.Product).Distinct().ToList();

    var result = distinctDates.Select(date => new PivotResult
    {
        Date = date,
        A = sales.Where(s => s.Date == date && s.Product == "A").Sum(s => s.Amount),
        B = sales.Where(s => s.Date == date && s.Product == "B").Sum(s => s.Amount)
    }).ToList();

    return result;
}

public static void Main()
{
    var sales = new List<Sale>
    {
        new Sale { Date = new DateTime(2023, 1, 1), Product = "A", Amount = 100 },
        new Sale { Date = new DateTime(2023, 1, 1), Product = "B", Amount = 200 },
        new Sale { Date = new DateTime(2023, 1, 2), Product = "A", Amount = 150 },
        new Sale { Date = new DateTime(2023, 1, 2), Product = "B", Amount = 250 }
    };

    var pivotedSales = PivotSales(sales);

    foreach (var item in pivotedSales)
    {
        Console.WriteLine($"Date: {item.Date}, A: {item.A}, B: {item.B}");
    }
}