Get Distinct property values from List

Question

I am trying to get distinct FullNames from a list that contains FullNames and IDs then displaying these in a listBox control. Is there a simple way to do it? Thanks Ben

using (DB2DataReader dr = command.ExecuteReader())
            {
                while (dr.Read())
                {

                Contact contact = new Contact();

                contact.ContactID = Convert.ToInt32(dr["CONTACT_ID"]);
                contact.FullName= dr["FULL_NAME"].ToString();


                myContacts.Add(contact);

                //contactsListBox.ItemsSource = myContacts.Distinct FullName??


            }
        }

Nonjuror

Answer 1

With LINQ:

var uniqueNames = myContacts.Select(c => c.FullName).Distinct().ToList();

should work. If the order is unimportant you could also use:

var names = new HashSet<string>();
while(dr.Read()) {
    ...
    names.Add(contact.FullName);
}

(and then use ToList() / OrderBy whatever you need)

Supple

Thanks alot! And how about the ItemsSource what should that be set to? – Nonjuror

Thanks I had tried that but no luck will play around with it. – Nonjuror

Answer 2

I think you can use different approaches here:

1. Make Sql query that queries distinct values.

2. Check that contact already in list. This approach assume that your class must redefine euqality operator. Or you can check that this contact id is already in list.

3. Use Linq query as mentioned above.

Tiernan

Cheers I went for the Linq option – Nonjuror

Answer 3

we can achieve like this:

var distinctItems = myItemsList.ToList().DistinctBy(x => x.ItemName);

Subgroup