Create a new List from two collections using LINQ expression

Question

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<Product> CartList = new List<Product>() {
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<Funds> Funding = new List<Funds>() {
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

Yogeshkumar Hadiya · 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(); } } }

peter · Answer

Could you please convert into VB.NET instead ? Thank you

Kiran Mohanty · Answer

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; }

peter · Answer

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 Hadiya · Answer

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.

peter · Answer

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();