CODEWITHSUNDEEP
c#wpflinq
David
David

Reputation: 271

C# Group results from List<T> into another List<T2> with selected fields

I was wondering if there's a simpler way to do this using LINQ or some other way...

I want to extract, from a List, all rows, grouping them by a particular field and storing the result in another different, like a List containing the grouped, not repeated, result of the search parameter.

Here's an example:

public class CustomObj
{
    public int DOC { get; set; }
    public string Desc { get; set; }
    public string Name{ get; set; }
}

public class Worker()
{
   public void DoWork()
   {
      List<CustomObj> objs = new List<CustomObj>();
      objs.Add(new CustomObj(1, "Type1", "Name1"));
      objs.Add(new CustomObj(1, "Type2", "Name1"));
      objs.Add(new CustomObj(2, "Type2", "Name2"));
      objs.Add(new CustomObj(3, "Type1", "Name1"));
      objs.Add(new CustomObj(3, "Type2", "Name1"));
      objs.Add(new CustomObj(3, "Type3", "Name1"));

      // HERE'S WHAT I'D LIKE TO DO
      // NOTE THAT THIS IS NOT A CORRECT FORMATED FUNCTION
      List<int> docs = objs.GroupBy(o => o.DOC).Select(o => o.DOC).ToList<int>();
   }
}

At the end my docs List should look like this

docs[0] = 1
docs[1] = 2
docs[2] = 3

In my current project I have, so far, 10 different objects, and I'm going to have to do this to all of them. Of course I'd like to avoid writing extensive functions to each one.

So if there's no other way at least I would like to know.

Thanks

Upvotes: 0

Views: 88

Answers (2)

devduder
devduder

Reputation: 394

Or, if you want to use GroupBy:

  var docs = objs.GroupBy(o => o.DOC).Select(o => o.Key).ToList();

Upvotes: 1

jakobbotsch
jakobbotsch

Reputation: 6337

What about:

List<int> docs = objs.Select(o => o.DOC).Distinct().ToList();

Upvotes: 5

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