Select users with similar name, but different password

Question

I need a function which returns a filtered list of distinct users with different usernames. I want to exclude the users who have similar usernames, but with different passwords.

Input
user1 ("Jim", 1111)
user2 ("Jim", 3333)
user3 ("Bill", 2222)
user4 ("Mike", 2222)

Output
user3 ("Bill", 2222)
user4 ("Mike", 2222)

private IEnumerable<User> GetCorrectUsers(IEnumerable<User> userList)
{
   IEnumerable<User> filtered= userList.GroupBy(user => user.UserName)
      .Select(g => g.???)
      .Where(p => p.Password).Distinct().Count() > 1;
   return filtered;
}

One step is missing.

Have you seen this? https://stackoverflow.com/questions/2078736/linq-with-group-by-having-count — Caius Jard, Oct 03 '18 at 08:24
If you ever get to storing real passwords, please remember to hash and salt them according to best practices at the time you implement such code. — ProgrammingLlama, Oct 03 '18 at 08:26
I am just thinking about interesting application design - password will be the key to determine a user. — Renatas M., Oct 03 '18 at 08:28
The password is just an example, I did not want to write the actual property. I don't care about different user's having similar passwords. — fota666, Oct 03 '18 at 08:36
What if we have 3 users as {Name = "Jim", Password = 1111}, {Name = "Jim", Password = 1111}, {Name = "Jim", Password = 2222}. Should we exclude all of them or select the one with '2222' password? — Kiryl Khadanovich, Oct 03 '18 at 08:57

Kiryl Khadanovich · Accepted Answer · 2018-10-03T08:54:37.477

2

from comment of Caius Jard the solution can be:

var filtered = users.GroupBy(x => x.Name)
            .Where(g => g.Select(grElem => grElem.Password).Distinct().Count() == 1).Select(x => x.First())
            .ToList();

edited Oct 03 '18 at 08:54

answered Oct 03 '18 at 08:35

Kiryl Khadanovich

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You haven't considered his password condition at all, He needs to omit users who have similar usernames with different passwords. – Dharani Kumar Oct 03 '18 at 08:40
Thanks, it looks okay. I'll test it. All of the users with same name, but different password must be excluded. – fota666 Oct 03 '18 at 10:20

Select users with similar name, but different password

1 Answers1