当用户没有电子邮件时查询 Active Directory 中的电子邮件时出现问题

Question

I'm querying our Active Directory with the following code:

            using (DirectorySearcher search = new DirectorySearcher(de))
            {
                search.PropertiesToLoad.Add("cn");
                search.PropertiesToLoad.Add("employeeid");
                search.PropertiesToLoad.Add("employeenumber");
                search.PropertiesToLoad.Add("distinguishedname");
                search.PropertiesToLoad.Add("mail");
                search.Filter = @"(&(objectClass=user)(employeeid=*)(employeenumber=*))";
                search.PageSize = 3000;

                SearchResultCollection src = search.FindAll();
                foreach (SearchResult rec in src)
                {
                    yield return new ADUser()
                    {
                        Name = rec.Properties["cn"][0].ToString(),
                        Path = rec.Properties["distinguishedname"][0].ToString(),
                        Acctno = rec.Properties["employeeid"][0].ToString(),
                        Personno = rec.Properties["employeenumber"][0].ToString(),
                        Email = rec.Properties["mail"][0].ToString()
                    };
                }

            }

As you can see, I'm trying to convert the results into an IEnumerable list of ADUser (my own class defined like this):

    public class ADUser
    {
        public string Name { get; set; }
        public string Path { get; set; }
        public string Acctno { get; set; }
        public string Personno { get; set; }
        public string Email { get; set; }
    }

However, my code crashes anytime I hit a user who does not have an email entry. It seems as though the SearchResult does not contain a property for mail when the user has no email. Is there a way to get the result to return the property with a null or empty value instead?

Thanks for your help.

Answer 1

using System;
using System.Collections.Generic;
using System.Web.Services;
using System.Web.Script.Serialization;
using System.DirectoryServices;
using System.Collections;
using System.DirectoryServices.AccountManagement;
using PropertyCollection = System.DirectoryServices.PropertyCollection;



    public class UserEmailInfo
    {
        public UserEmailInfo()
        {
        }
        public string DisplayName { get; set; }
        public string DisplayEmail { get; set; }
    }


    [WebMethod]
    public string GetADUserDisplayNameAndEmailAddress(string displayName)
    {
        //var search = new DirectorySearcher(new DirectoryEntry("LDAP://domain.local"));

        List<UserEmailInfo> displayNameEmailAddress = new List<UserEmailInfo>();

        var search = new DirectorySearcher(new DirectoryEntry("LDAP://DC=domain,DC=local"));
        string ldapfilter = "(&(ObjectClass=user)(objectCategory=person)(name={0}))";

        search.Filter = String.Format(ldapfilter, displayName);
        search.PropertiesToLoad.Add("displayname");
        search.PropertiesToLoad.Add("mail");

        SearchResult result = search.FindOne();

            if (result == null)
            {
                displayNameEmailAddress.Add(new UserEmailInfo()
                {
                    DisplayName = "none",
                    DisplayEmail = "none"
                });
            }
            else
            {
                if (result.Properties.Contains("mail") && result.Properties["mail"] != null)
                {
                    displayNameEmailAddress.Add(new UserEmailInfo()
                    {
                        DisplayName = result.Properties["displayname"][0].ToString(),
                        DisplayEmail = result.Properties["mail"][0].ToString()
                    });
                }
            }


            
       
                 
        //return emailAddress;
        string myJsonString = (new JavaScriptSerializer()).Serialize(displayNameEmailAddress);
        return myJsonString;
    }

Answer 2

Edit after comment:

if (rec.Properties.Contains("mail") && rec.Properties["mail"] != null)
{
  Email = rec.Properties["mail"][0].ToString()
}
else
{
   Email = "No mail"; # or Email = ""; if you want no text returned 

}

Answer 3

You should be able to use the ?? "null coalescing" operator with the email string.

string s1 = null; string s2 = s1 ?? "S1 was null." // Prints: s2 == "S1 was null."