如何在其他类型的列表中选择所有不同的字符串？

Question

I'm still very new with LINQ. I have the following "simplified" data structure:

List<List<Field>> myData = new List<List<Field>>();

Field consists of two string members, Type and Name .

My goal is to get a List<string> containing all distinct Name corresponding to a given Type . My first approach is this:

var test = myData
  .Where(a => a.FindAll(b => b.Type.Equals("testType"))
  .Select(c => c.Name)
  .Distinct());

Does somebody have a hint for me? =)

Answer 1

You just need to use SelectMany to flatten your list of lists and then proceed as normal

var test = myData.SelectMany(x => x)
    .Where(x => x.Type == "testType")
    .Select(x => x.Name)
    .Distinct()
    .ToList();

Or in query syntax

var test = (from subList in myData
            from item in subList
            where item.Type == "testType"
            select item.Name).Distinct().ToList();

Answer 2

Another way to do it using query notation:

var test= from list in myData
          from e in list
          where e.Type=="testType"
          group e.Name by e.Name into g
          select g.Key;

But is better go for one of the @juharr's solutions