Create a new List from two collections using LINQ expression

peter

5y1.4k

I want to return another List from two collections as shown. The task is to combine the two on VendorID and calculate a new price. The lists are not static and can enlarge in size.

IList CartList = new List() {
new Product() { VendorID = 1, Email = "John@yahoo", Price = 130,Name ="john" },
new Product() { VendorID = 1, Email = "john@yahoo", Price = 210,Name="john" },
new Product() { VendorID = 2, Email = "Bill@yahoo", Price = 180,Name ="Bill" },
new Product() { VendorID = 3, Email = "Ram@yahoo" , Price = 200,Name="Ram" }

};

IList Funding = new List() {
new Funds(){ VendorID = 1, Funds=30},
new Funds(){ VendorID = 2, Funds=40}

};

Result: Vendor Email                       Price
               1        John@yahoo             310 (ie 340-30)
               2          Bill@yahoo             140 (ie 180-40)
               3          Ram@yahoo           200

6 Replies

Know the answer? Post it — somebody with the same question will find it here.

Yogeshkumar Hadiya5y ago
Accepted answer
Hi please try below code.
using System;
using System.Collections.Generic;
using System.Linq;

namespace ListExample
{
    class Program
    {
        public class Product
        {
            public int VendorID { get; set; }
            public string Email { get; set; }
            public string Name { get; set; }
            public int Price { get; set; }
        }
        public class Funding
        {
            public int VendorID { get; set; }
            public int Funds { get; set; }
        }
        static void Main(string[] args)
        {
            List CartList = new List() {
                new Product() { VendorID = 1, Email = "John@yahoo", Price = 130,Name ="john" },
                new Product() { VendorID = 1, Email = "john@yahoo", Price = 210,Name="john" },
                new Product() { VendorID = 2, Email = "Bill@yahoo", Price = 180,Name ="Bill" },
                new Product() { VendorID = 3, Email = "Ram@yahoo" , Price = 200,Name="Ram" }

                };

            List Funding = new List() {
            new Funding(){ VendorID = 1, Funds=30},
            new Funding(){ VendorID = 2, Funds=40}

            };


            List FinalList = new List();
            foreach (var item in CartList)
            {
                Product product = new Product();
                product.Email = item.Email;
                product.VendorID = item.VendorID;
                int price = CartList.Where(x => x.VendorID == item.VendorID).Select(x => x.Price).Sum();
                if (Funding.Any(x => x.VendorID == item.VendorID))
                {
                    price = price - Funding.Where(x => x.VendorID == item.VendorID).Select(x => x.Funds).Sum();
                }
                product.Price = price;
                if (!FinalList.Any(x => x.VendorID == item.VendorID))
                    FinalList.Add(product);
            }

            Console.ReadKey();
        }
    }
}
peter5y ago
Could you please convert into VB.NET instead ?

Thank you
Kiran Mohanty5y ago
Hi,
Try this lamda expression.
IList CartList = new List() {
               new Product() { VendorID = 1, Email = "John@yahoo", Price = 130,Name ="john" },
               new Product() { VendorID = 1, Email = "john@yahoo", Price = 210,Name="john" },
               new Product() { VendorID = 2, Email = "Bill@yahoo", Price = 180,Name ="Bill" },
               new Product() { VendorID = 3, Email = "Ram@yahoo" , Price = 200,Name="Ram" }
           };

           IList Funding = new List() {
               new Funds(){ VendorID = 1, Fund=30},
               new Funds(){ VendorID = 2, Fund=40}
           };
var result = CartList.GroupBy(c => new { c.VendorID, c.Email, c.Price })
                .Select(group => new { VendorID = group.Key.VendorID, Email = group.Key.Email, Price = group.Sum(p => p.Price) })
                .SelectMany(x =>
                       Funding.Where(y => y.VendorID == x.VendorID)?.DefaultIfEmpty(),
                         (x, y) => new
                         {
                             x.VendorID,
                             x.Email,
                             Price = (x.Price - y?.Fund ?? 0)
                         }
                     )
                .ToList();
public class Product
{
     public int VendorID;
     public string Email;
     public int Price;
     public string Name;
}

public class Funds
{
     public int VendorID;
     public int Fund;
}
peter5y ago
Yes, This is an alternative solution. It uses the join and Group operator instead to sum the results of query.
I was given this example by somebody else, but i dont know if it works, as i not able to convert into VB.NET that i am operating. My guess it does not?
I thought maybe you could test if it is working and convert over to VB.NET.
Yogeshkumar Hadiya5y ago
Hi if you solve problem with my answer i request you to please mark as accepted. And below code you need in VB or in C# please clarify.
peter5y ago
That works very good,thanks.

I had another solution but could not translate into VB.NET that i was eager to try. I wonder if you would be able to adapt it ?

var q = (from p in CartList group p by new {
p.VendorID, p.Email }
into g join f in Funding on g.Key.VendorID equals f.VendorID into pf
from re in pf.DefaultIfEmpty()
select new Result {
VendorID = g.Key.VendorID,
Email = g.Key.Email,
Price = g.Sum(p=>p.Price) - (re==null?0:re.Fund) }) .ToList();