Linq查询的独特价值

Question

I have the below class and linq query I am using to populate a grid !

The Title is the same for every row returned. What I am trying to do is populate mString with the distinct Title from the query so I can bind it to a seperate textblock.

I probably didnt need to show all the code, but maybe it will help. How can I show the distinct Title .

public class Items
{
    public int Id { get; set; }
    public string Details { get; set; }
    public string Title { get; set; }
    public int NewNumber { get; set; }
}

private ObservableCollection<Items>  mItem = new ObservableCollection<Items>();
private string mString = string.Empty;

public string SpecTitle
{
    get { return mString; }
}

public ObservableCollection<Items> GetItems
{
    get { return mItem; }
}

Here is the linq query

var results = (from z in mContext.View
               orderby z.ItemNumber ascending
               where z.ItemId == mId
               select new Items()
               {                                         
                   Id = z.ItemId,
                   Details = z.Details,
                   Title = z.ItemTitle,
                   NewNumber = z.ItemNumber
               });

List<Items> mNewItems = results.ToList();
mItem.Clear();
mNewItems.ForEach(y => mItem.Add(y));

Answer 1

Converting my comment into an answer:

just do Items.Select(x => x.Title).Distinct(); .

Answer 2

var titleList = mNewItems.Select(i => i.Title).Distinct().ToList();

Answer 3

There is an additional library called moreLinq https://code.google.com/p/morelinq/ that has an extenction distinctby that you can you to distinct based on the given key.

it would as simle as this

   var results = (from z in mContext.View
                                 orderby z.ItemNumber ascending
                                 where z.ItemId == mId
                                 select new Items()
                                 {                                         
                                     Id = z.ItemId,
                                     Details = z.Details,
                                     Title = z.ItemTitle,
                                     NewNumber = z.ItemNumber

                                 }).DistinctBy(c=>c.Title).ToList();

Answer 4

You can implement your custom comparer for distinct:

public class ItemsComparer : IEqualityComparer<Items>
{
    public bool Equals(Items x, Items y)
    {
        return x.Title == y.Title;
    }

    public int GetHashCode(Items obj)
    {
        return obj.Title.GetHashCode();
    }
}

then just use

var titleList = mNewItems.Distinct(new ItemsComparer()).Select(t=>t.Items);