UserFriendlyIdPersistentObject.cs

using System;
using DevExpress.Xpo;
using System.ComponentModel;
using DevExpress.Persistent.BaseImpl;
using Microsoft.Extensions.DependencyInjection;

namespace GenerateUserFriendlyId.Module.BusinessObjects {
    //Dennis: Uncomment this code if you want to have the SequentialNumber column created in each derived class table.
    [NonPersistent]
    public abstract class UserFriendlyIdPersistentObject : BaseObject, ISupportSequentialNumber {
        private long _SequentialNumber;
        private SequenceGenerator sequenceGenerator;
        public UserFriendlyIdPersistentObject(Session session)
            : base(session) {
        }
        [Browsable(false)]
        //Dennis: Comment out this code if you do not want to have the SequentialNumber column created in each derived class table.
        [Indexed(Unique = false)]
        public long SequentialNumber {
            get { return _SequentialNumber; }
            set { SetPropertyValue("SequentialNumber", ref _SequentialNumber, value); }
        }
        private void OnSequenceGenerated(long newId) {
            SequentialNumber = newId;
        }
        protected override void OnSaving() {
            try {
                base.OnSaving();
                if(!(Session is NestedUnitOfWork)
                    && (Session.DataLayer != null)
                        && (Session.ObjectLayer is SimpleObjectLayer)
                        //OR
                        //&& !(Session.ObjectLayer is DevExpress.ExpressApp.Security.ClientServer.SecuredSessionObjectLayer)
                            && Session.IsNewObject(this)) {
                    GenerateSequence();
                }
            } catch {
                CancelSequence();
                throw;
            }
        }
        // Override this method to create multiple sequences based on the current object's property values
        protected virtual string GetSequenceName() {
            return SequenceGenerator.GetBaseSequenceName(ClassInfo);
        }
        public void GenerateSequence() {
            var typeToExistsMap = new HashSet<string>();
            foreach (var item in Session.GetObjectsToSave().OfType<UserFriendlyIdPersistentObject>()) {
                typeToExistsMap.Add(item.GetSequenceName());
            }
            if (sequenceGenerator == null) {
                sequenceGenerator = Session.ServiceProvider.GetRequiredService<SequenceGeneratorProvider>().GetSequenceGenerator();
            }
            sequenceGenerator.EnsureSequencesUnlocked(typeToExistsMap);
            SubscribeToEvents();
            OnSequenceGenerated(sequenceGenerator.GetNextSequence(GetSequenceName()));
        }
        private void AcceptSequence() {
            if (sequenceGenerator != null) {
                try {
                    sequenceGenerator.Accept();
                }
                finally {
                    CancelSequence();
                }
            }
        }
        private void CancelSequence() {
            UnSubscribeFromEvents();
            if (sequenceGenerator != null) {
                sequenceGenerator.Close();
            }
        }
        private void Session_AfterCommitTransaction(object sender, SessionManipulationEventArgs e) {
            AcceptSequence();
        }
        private void Session_AfterRollBack(object sender, SessionManipulationEventArgs e) {
            CancelSequence();
        }
        private void Session_FailedCommitTransaction(object sender, SessionOperationFailEventArgs e) {
            CancelSequence();
        }
        private void SubscribeToEvents() {
            if(!(Session is NestedUnitOfWork)) {
                Session.AfterCommitTransaction += Session_AfterCommitTransaction;
                Session.AfterRollbackTransaction += Session_AfterRollBack;
                Session.FailedCommitTransaction += Session_FailedCommitTransaction;
            }
        }
        private void UnSubscribeFromEvents() {
            if(!(Session is NestedUnitOfWork)) {
                Session.AfterCommitTransaction -= Session_AfterCommitTransaction;
                Session.AfterRollbackTransaction -= Session_AfterRollBack;
                Session.FailedCommitTransaction -= Session_FailedCommitTransaction;
            }
        }
    }
}