Linq: group objects and remove duplicate elements from their child elements

Question

So I have this class structure:

public class ObjectCode

{

    public string Code { get; set; }

}



class Configuration

{

    public int Id { get; set; }



    public string Name { get; set; }



    public IEnumerable<ObjectCode> Objects { get; set; }

}

I am receiving a list of

Configuration

from multiple providers. My problem is that I don't know how to group these objects by Id and put the distinct

ObjectCode

objects from all the

Configuration

objects in the resulting entity.

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Answer 1

Use SelectMany inside each group in GroupBy:

var res = congigs
    .GroupBy(c => new {c.Id, c.Name})
    .Select(g =>
        new Configuration {
            Id = g.Key.Id
        ,   Name = g.Key.Name
        ,   Objects = g
               .SelectMany(c => c.Objects)
               .GroupBy(c => c.Code)
               .Select(gg => gg.First())
        }
    ).ToList();

The above assumes that Config objects with the same Id also have identical Names.

Linq: group objects and remove duplicate elements from their child elements

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