Full outer join linq using union - linq

Question

I have two lists
var left={[ID=1,Name='A',Qty1=0,Qty2=5],[ID=2,Name=B,Qty1=0,Qty2=52]};
var right={[ID=1,Name='A',Qty1=57,Qty2=0],[ID=2,Name=B,Qty1=84,Qty2=0]};
var outer=left.union(right);
I want to get the following result:
outer={[ID=1,Name='A',Qty1=57,Qty2=5],[ID=2,Name=B,Qty1=84,Qty2=52]}
How do I get that? How to write the comparator class?
Edit:
I have two lists
var target=(...new ClassA{ID=a.ID,Name=a.Name,TargetQty=b.TargetValue}).ToList();
var sales=(....new ClassA{ID=a.ID,Name=a.Name,SalesQty=b.SaleValue}).ToList();
Now I want a full outer join. How can I get that?

Answer 1

It sounds like you possibly want an inner join:
var query = left.Join(right, l => l.Id, r => r.Id,
(l, r) => new { l.Id, l.Name, r.Qty1, l.Qty2 });
(You may want to join on both Id and Name; it's not clear whether the Id is enough.)

Answer 2

In this case union will not bring the desired output.
Jon Skeet is right in his direction that inner join will do what you want. Considering your question it seems like you need to have inner join with sum of respective row like below. If it is not your requirement then you need to modify your question.
public class Program
{
public static void Main()
{
var left= new List<Product>(){
new Product(){ID=1,Name="A",Qty1=0,Qty2=5},
new Product(){ID=2,Name="B",Qty1=0,Qty2=52}
};
var right= new List<Product>(){
new Product(){ID=1,Name="A",Qty1=57,Qty2=0},
new Product(){ID=2,Name="B",Qty1=84,Qty2=0}
};
var outer=left.Union(right);
Console.WriteLine(outer.Count());//will be four which is not expected.
var query = left.Join(right, d => d.ID, e=> e.ID, (f,g) => new Product(){ID = f.ID, Name = f.Name, Qty1 = f.Qty1+g.Qty1, Qty2 = f.Qty2+g.Qty2});
foreach(var item in query)
{
item.Print();
}
}
}
public class Product {
public int ID{get; set;}
public string Name{get; set;}
public int Qty1{get; set;}
public int Qty2{get; set;}
public void Print()
{
Console.WriteLine("ID : {0}", ID);
Console.WriteLine("Name: {0}", Name);
Console.WriteLine("Qty1: {0}", Qty1);
Console.WriteLine("Qty2: {0}", Qty2);
}
}
Here is output from above code:
4
ID : 1
Name: A
Qty1: 57
Qty2: 5
ID : 2
Name: B
Qty1: 84
Qty2: 52
You may modify and test this code here => link