时间：2019-05-10 标签：c#group list items里面有部分相同的文本

Question

I have this list listemailsMsgs that have items like this:

email1@hotmail.com;mensagem1;assunto1
email2@hotmail.com;mensagem1;assunto1
email3@hotmail.com;mensagem2;assunto2

The first two items have different emails, but the messages are the same. The third item has a different email and a different message.

I am having a hard time finding a way to group the first two items into just one, like this:

email1@hotmail.com;email2@hotmail.com;mensagem1;assunto1

Does anyone have any idea of how to do that?

Answer 1

First and foremost, try to convert the given values into ac# model, so that it will be easy for you to solve this kind of problem.

In the mentioned question, the item value contains the three sections, so create an Item class to represent it.

    public class Item
    {
        public string EmailAddress { get; }
        public string FirstMessageField { get; }
        public string SecondMessageField { get; }

        public Item(string message)
        {
            var result = message.Split(';');
            EmailAddress = result[0];
            FirstMessageField = result[1];
            SecondMessageField = result[2];
        }
    }

Then, convert all your given string values into a List of Item.

        var input = new List<Item>
        {
            new Item("email1@hotmail.com;mensagem1;assunto1"),
            new Item("email2@hotmail.com;mensagem1;assunto1"),
            new Item("email3@hotmail.com;mensagem2;assunto2")
        };

Finally, use LINQ operations to group your values based on the message fields:

        var output = input
            .GroupBy(x => new { x.FirstMessageField, x.SecondMessageField })
            .Select(x =>
            {
                var emailAddresses = string.Join(';', x.Select(y => y.EmailAddress).ToArray());
                return $"{emailAddresses};{x.Key.FirstMessageField};{x.Key.SecondMessageField}";
            })
            .ToList();