Group list by items in sub list using LINQ

Question

I have this list:

CustomerA

Cod123
Cod456

CustomerB

Cod456
Cod789

CustomerC

Cod888
Cod999

I want to return this using LINQ:

CustomerA

Cod123
Cod456

CustomerC

Cod888
Cod999

Because CustomerA and CustomerB have the same cod: Cod456

My classes:

    public class Customer
{
    public string Name { get; set; }
    public List<Cod> Cods { get; set; }
}

public class Cod
{
    public string Number { get; set; }
}

My attempt not build in GroupBy line.

            var customersOK = customersDuplicatedCods
                    .GroupBy(p => p.Cods.Number)
                    .Select(g => g.First())
                    .ToList();

Can you give us actual C# classes? You're example is too vague to work with. — Cameron, Apr 12 '17 at 19:46
It sounds like you don't actually want them grouped, you just want duplicates removed. — Harrison Paine, Apr 12 '17 at 20:15

score 1 · Answer 1 · edited May 23 '17 at 12:02

It sounds like you don't actually want them grouped, you just want duplicates removed.

This Q&A explains how to do that.

Basically you would create an IEqualityComparer<Customer>

class DistinctItemComparer : IEqualityComparer<Customer> 
{
    public bool Equals(Customer x, Customer y) 
    {
        return x.Cods.Intersect(y.Cods).Any();
    }

    public int GetHashCode(Customer obj) 
    {
        return 0;
    }
}

And call it by customers.Distinct(new DistinctItemComparer())

Group list by items in sub list using LINQ

1 Answers1