How to use LINQ Group Records and use Distinct-CodePudding

given this Records

class Record
{
    DateTime Date {get; set;}
    string Article {get; set;}
    string Platform { get; set;}
    string Amount { get; set;}
}

With a sql query I get a list of Records and want to Group the Platforms by Article.

I do this query:

List<Record> recordList = FetchRecords();
var group = recordList.GroupBy(
    f => f.Article, 
    (key, g) => new 
    { 
        Article= key, 
        Platforms = g.Select(p => p.Platform).ToList() 
    });

There are around 120 different Articles and about 30 different platforms, so the expected amount of items in group is around 120 yet I am recieving thousands of items. Items in record list are a lot as its the stock of all articles in the last 30 Days so I want to get a distinct list of Articles. I just can't figure out where to do this. what am I missing?

Edit:

After further inspecting the Data at runtime I just noticed that I have it backwards. the Articles are already correctly grouped, the platforms are the ones that need to be distinct, like Astrid E was guessing in the comments

CodePudding user response：

You can return distinct values of the Platform collection by using Enumerable.Distinct().

The Platforms value in the result selector in your .GroupBy() operation should be computed as follows:

Platforms = g.Select(p => p.Platform).Distinct().ToList()

CodePudding user response：

Maybe you could try something like this:

var group = recordList.GroupBy(r => r.Article)
                      .Select(a =>
                        new
                        {
                            Article = a.Key,
                            Platforms = a.GroupBy(g => g.Platform)
                        });