DirectorySearcher SizeLimit和List.Sort产生不必要的结果C＃

Question

I have some code which takes an input string of users to search for in Active Directory. I limit the number of results (to 20) returned for searches. I then sort the results by the Active Directory created date descending. However, if I have more than 20 results (eg 100) on a particular user (eg 'Smith'), I get 20 users (due to my limitiing of the results) sorted by created date, but it's the last 20 of the 100 sorted by created date, where I want the first 20. If I remove the SizeLimit, I get all 100 results in the correctly sorted order. Below is my code, not sure what needs to be adjusted.

        public void getADSearchResults(string searchString)
        {

            //Create list to hold ADUser objects
            List<ADUser> users = new List<ADUser>();
            string[] allUsers = searchString.Split(new Char[] { ',' }, userSearchLimit);

            var json = "";

            foreach (string name in allUsers)
            {
                //Connect to the root of the active directory domain that this computer is bound to with the default credentials; seems to cover employee and provider OUs at minimum
                var rootDirectory = new DirectoryEntry();

                DirectorySearcher adSearch = new DirectorySearcher(rootDirectory);

                adSearch.Filter = "(&(objectClass=user)(anr=" + name + "))";

                //LIMIT NUMBER OF RESULTS PER USER SEARCHED
                adSearch.SizeLimit = 20;

                // Go through all entries from the active directory.
                foreach (SearchResult adUser in adSearch.FindAll())
                {
                    DirectoryEntry de = adUser.GetDirectoryEntry();

                    string userName = "";
                    userName = adUser.Properties["sAMAccountName"][0].ToString();

                    string createdDate = "";
                    createdDate = adUser.Properties["whenCreated"][0].ToString();

                    ADUser aduser = new ADUser(userName, createdDate);

                    users.Add(aduser);
                }
            }

            users.Sort((x, y) => DateTime.Parse(y.createdDate).CompareTo(DateTime.Parse(x.createdDate)));

            json = new JavaScriptSerializer().Serialize(new { users = users });

            //return json;
            HttpContext.Current.Response.Write(json);
        }

public class ADUser
{
    public ADUser(string UserName, string CreatedDate)
    {
        userName = UserName;
        createdDate = CreatedDate;
...
}

Answer 1

I suppose you have a logical mistake there.

I suppose you need to cut this operation in two pieces:

1) Get the whole files and users. 2) Make a loop to critic if an user has appeared before and, if so, jump all his records until the next user.

The problem may be related to the fact you want to perform it in a single operation AND cutting only the 20 first/last records.

Good luck

PS: can you put a USER FILTER there? I mean, after has the whole files in a LIST filter it by user?