How to use Linq to compare two complex lists | C# Online Compiler

How to use Linq to compare two complex lists by yongshun950824

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text.Json;

public class Program
{
	public static void Main()
	{
		List<Item> items = new List<Item>()
		{
			new Item
			{
				Id = 1,
				Name = "Item 01",
				Packages = new List<Package>
				{
					new Package
					{
						Id = 1,
						Name = "SINGLE"
					},
					new Package
					{
						Id = 2,
						Name = "PACK"
					}
				}
			},
			new Item
			{
				Id = 2,
				Name = "Item 02",
				Packages = new List<Package>
				{
					new Package
					{
						Id = 1,
						Name = "SINGLE"
					},
					new Package
					{
						Id = 2,
						Name = "PACK"
					}
				}
			},
			new Item
			{
				Id = 3,
				Name = "Item 03",
				Packages = new List<Package>
				{
					new Package
					{
						Id = 1,
						Name = "SINGLE"
					},
					new Package
					{
						Id = 2,
						Name = "PACK"
					}
				}
			},
			new Item
			{
				Id = 4,
				Name = "Item 04",
				Packages = new List<Package>
				{
					new Package
					{
						Id = 1,
						Name = "SINGLE"
					},
					new Package
					{
						Id = 2,
						Name = "PACK"
					}
				}
			},
			new Item
			{
				Id = 5,
				Name = "Item 04",
				Packages = new List<Package>
				{
					new Package
					{
						Id = 1,
						Name = "SINGLE"
					},
					new Package
					{
						Id = 2,
						Name = "PACK"
					}
				}
			},
			new Item
			{
				Id = 6,
				Name = "Item 06",
				Packages = new List<Package>
				{
					new Package
					{
						Id = 1,
						Name = "SINGLE"
					},
					new Package
					{
						Id = 2,
						Name = "PACK"
					}
				}
			}
		};
		List<RetailPrice> prices = new List<RetailPrice>()
		{
			new RetailPrice
			{
				Item = 1,
				Package = 1,
				Price = 1
			},
			new RetailPrice
			{
				Item = 2,
				Package = 2,
				Price = 2
			},
			new RetailPrice
			{
				Item = 3,
				Package = 1,
				Price = 3
			},
			new RetailPrice
			{
				Item = 4,
				Package = 2,
				Price = 4
			},
			new RetailPrice
			{
				Item = 5,
				Package = 3,
				Price = 5
			}, // Bad one
			new RetailPrice
			{
				Item = 6,
				Package = 2,
				Price = 6
			}
		};
		// How would I do this in linq?
		HashSet<string> itemPackages = new HashSet<string>();
		foreach (var item in items)
		{
			foreach (var package in item.Packages)
			{
				itemPackages.Add($"{item.Id}|{package.Id}");
			}
		}

		List<RetailPrice> badPrices = new List<RetailPrice>();
		List<RetailPrice> goodPrices = new List<RetailPrice>();
		foreach (var price in prices)
		{
			if (!itemPackages.Contains($"{price.Item}|{price.Package}"))
			{
				badPrices.Add(price);
			}
			else
			{
				goodPrices.Add(price);
			}
		}
		
		goodPrices = prices
			.Where(price => items.Any(item => price.Item == item.Id && item.Packages.Any(package => price.Package == package.Id)))
			.ToList();
		
		badPrices = prices
			.Where(price => !items.Any(item => price.Item == item.Id && item.Packages.Any(package => price.Package == package.Id)))
			.ToList();

		Console.WriteLine(JsonSerializer.Serialize(goodPrices, new JsonSerializerOptions { WriteIndented = true }));
		Console.WriteLine(JsonSerializer.Serialize(badPrices, new JsonSerializerOptions { WriteIndented = true }));
	}
}

public class Item
{
	public int Id { get; set; }
	public string Name { get; set; }
	public List<Package> Packages { get; set; }
}

public class Package
{
	public int Id { get; set; }
	public string Name { get; set; }
}

public class RetailPrice
{
	public int Item { get; set; }
	public int Price { get; set; }
	public int Package { get; set; }
}

​x
 
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text.Json;
​
public class Program
{
    public static void Main()
    {
        List<Item> items = new List<Item>()
        {
            new Item
            {
                Id = 1,
                Name = "Item 01",
                Packages = new List<Package>
                {
                    new Package
                    {
                        Id = 1,
                        Name = "SINGLE"
                    },
                    new Package
                    {
                        Id = 2,
                        Name = "PACK"
                    }
                }
            },
            new Item
            {
                Id = 2,
                Name = "Item 02",
                Packages = new List<Package>
                {
                    new Package
                    {
                        Id = 1,
                        Name = "SINGLE"
                    },
                    new Package
                    {
                        Id = 2,
                        Name = "PACK"
                    }
                }
            },
            new Item
            {
                Id = 3,
                Name = "Item 03",
                Packages = new List<Package>
                {
                    new Package
                    {
                        Id = 1,
                        Name = "SINGLE"
                    },
                    new Package
                    {
                        Id = 2,
                        Name = "PACK"
                    }
                }
            },
            new Item
            {
                Id = 4,
                Name = "Item 04",
                Packages = new List<Package>
                {
                    new Package
                    {
                        Id = 1,
                        Name = "SINGLE"
                    },
                    new Package
                    {
                        Id = 2,
                        Name = "PACK"
                    }
                }
            },
            new Item
            {
                Id = 5,
                Name = "Item 04",
                Packages = new List<Package>
                {
                    new Package
                    {
                        Id = 1,
                        Name = "SINGLE"
                    },
                    new Package
                    {
                        Id = 2,
                        Name = "PACK"
                    }
                }
            },
            new Item
            {
                Id = 6,
                Name = "Item 06",
                Packages = new List<Package>
                {
                    new Package
                    {
                        Id = 1,
                        Name = "SINGLE"
                    },
                    new Package
                    {
                        Id = 2,
                        Name = "PACK"
                    }
                }
            }
        };
        List<RetailPrice> prices = new List<RetailPrice>()
        {
            new RetailPrice
            {
                Item = 1,
                Package = 1,
                Price = 1
            },
            new RetailPrice
            {
                Item = 2,
                Package = 2,
                Price = 2
            },
            new RetailPrice
            {
                Item = 3,
                Package = 1,
                Price = 3
            },
            new RetailPrice
            {
                Item = 4,
                Package = 2,
                Price = 4
            },
            new RetailPrice
            {
                Item = 5,
                Package = 3,
                Price = 5
            }, // Bad one
            new RetailPrice
            {
                Item = 6,
                Package = 2,
                Price = 6
            }
        };
        // How would I do this in linq?
        HashSet<string> itemPackages = new HashSet<string>();
        foreach (var item in items)
        {
            foreach (var package in item.Packages)
            {
                itemPackages.Add($"{item.Id}|{package.Id}");
            }
        }
​
        List<RetailPrice> badPrices = new List<RetailPrice>();
        List<RetailPrice> goodPrices = new List<RetailPrice>();
        foreach (var price in prices)
        {
            if (!itemPackages.Contains($"{price.Item}|{price.Package}"))
            {
                badPrices.Add(price);
            }
            else
            {
                goodPrices.Add(price);
            }
        }
        
        goodPrices = prices
            .Where(price => items.Any(item => price.Item == item.Id && item.Packages.Any(package => price.Package == package.Id)))
            .ToList();
        
        badPrices = prices
            .Where(price => !items.Any(item => price.Item == item.Id && item.Packages.Any(package => price.Package == package.Id)))
            .ToList();
​
        Console.WriteLine(JsonSerializer.Serialize(goodPrices, new JsonSerializerOptions { WriteIndented = true }));
        Console.WriteLine(JsonSerializer.Serialize(badPrices, new JsonSerializerOptions { WriteIndented = true }));
    }
}
​
public class Item
{
    public int Id { get; set; }
    public string Name { get; set; }
    public List<Package> Packages { get; set; }
}
​
public class Package
{
    public int Id { get; set; }
    public string Name { get; set; }
}
​
public class RetailPrice
{
    public int Item { get; set; }
    public int Price { get; set; }
    public int Package { get; set; }
}

View IL Code