Moved implementation of check for existance of username on creating user from user service to repository.

src/Umbraco.Abstractions/Persistence/Repositories/IUserRepository.cs

@@ -20,8 +20,24 @@ namespace Umbraco.Core.Persistence.Repositories
         /// </summary>
         /// <param name="username"></param>
         /// <returns></returns>
+        [Obsolete("This method will be removed in future versions.  Please use ExistsByUserName instead.")]
         bool Exists(string username);
 
+        /// <summary>
+        /// Checks if a user with the username exists
+        /// </summary>
+        /// <param name="username"></param>
+        /// <returns></returns>
+        bool ExistsByUserName(string username);
+
+
+        /// <summary>
+        /// Checks if a user with the login exists
+        /// </summary>
+        /// <param name="username"></param>
+        /// <returns></returns>
+        bool ExistsByLogin(string login);
+
         /// <summary>
         /// Gets a list of <see cref="IUser"/> objects associated with a given group
         /// </summary>

src/Umbraco.Infrastructure/Persistence/Repositories/Implement/UserRepository.cs

@@ -626,6 +626,11 @@ ORDER BY colName";
         }
 
         public bool Exists(string username)
+        {
+            return ExistsByUserName(username);
+        }
+
+        public bool ExistsByUserName(string username)
         {
             var sql = SqlContext.Sql()
                 .SelectCount()
@@ -635,6 +640,16 @@ ORDER BY colName";
             return Database.ExecuteScalar<int>(sql) > 0;
         }
 
+        public bool ExistsByLogin(string login)
+        {
+            var sql = SqlContext.Sql()
+                .SelectCount()
+                .From<UserDto>()
+                .Where<UserDto>(x => x.Login == login);
+
+            return Database.ExecuteScalar<int>(sql) > 0;
+        }
+
         /// <summary>
         /// Gets a list of <see cref="IUser"/> objects associated with a given group
         /// </summary>

src/Umbraco.Infrastructure/Services/Implement/UserService.cs

@@ -109,9 +109,9 @@ namespace Umbraco.Core.Services.Implement
             User user;
             using (var scope = ScopeProvider.CreateScope())
             {
-                var loginExists = scope.Database.ExecuteScalar<int>("SELECT COUNT(id) FROM umbracoUser WHERE userLogin = @Login", new { Login = username }) != 0;
+                var loginExists = _userRepository.ExistsByLogin(username);
                 if (loginExists)
-                    throw new ArgumentException("Login already exists"); // causes rollback // causes rollback
+                    throw new ArgumentException("Login already exists"); // causes rollback
 
                 user = new User(_globalSettings)
                 {