Merging lists in another list using LINQ c#

Question

I have an author class like this

public class Author : IEquatable<Author>
    {
        public string Name { get; private set; }
        public List<PublicationData> Publications { get; private set }; 

        public Author(string name, List<PublicationData> publications)
        {
            Name = name;
            Publications = publications;
        }

        public override string ToString()
        {
            string lines = Name + "\n";
            foreach (PublicationData publication in Publications)
                lines += publication.ToString() + "\n";
            return lines;
        }

        public bool Equals(Author other)
        {
            return Name.Equals(other.Name);
        }

        public override int GetHashCode()
        {
            return Name.GetHashCode();
        }
    }

And I have publication class like this

public class PublicationData : IEquatable<PublicationData>
    {
        public string Code { get; set; }
        public int Amount { get; set; }
        public int Subscription_Length { get; set; }

        public PublicationData(string name, int amount, int subscription_Length)
        {
            Code = name;
            Amount = amount;
            Subscription_Length = subscription_Length;
        }

        public override string ToString()
        {
            return String.Format($"{Code}, {Amount}, {Subscription_Length}");
        }

        public bool Equals(PublicationData other)
        {
            return Code.Equals(other.Code);
        }

        public override int GetHashCode()
        {
            return Code.GetHashCode();
        }
    }

Then I have a list of authors that look like this:

AuthorA - PublicationA

AuthorB - PublicationB

AuthorB - PublicationC

I want to get something like this as a new object:

AuthorA - PublicationA

AuthorB - PublicationB - PublicationC

I assume the code should look something like this:

var filtered = authors.Select(nn => new Author
            (
                nn.Name,

                // merge publication lists

             )).Distinct()
               .ToList();

I just have no idea how do I do this. Can anyone suggest something?

Answer 1

You can also achieve it via the following code.

var query = from author in authors
            group author by author.AuthorName;
foreach (var group in query)
{
    Console.WriteLine(group.Key);
    // Nested foreach is required to access group items.
    foreach (var g in group)
    {
        Console.WriteLine($"\t{g.Publication}");
    }
}

Here is a document Group query results you can refer to.

Answer 2

It seems that you are looking for GroupBy method:

authors
    .GroupBy(a => a.Name)
    .Select(g => new Author(
        g.Key,
        g.SelectMany(ga => ga.Publications).ToList()))