Improved repair.

backend/src/Squidex.Domain.Apps.Entities.MongoDb/Assets/MongoAssetFolderRepository_SnapshotStore.cs

@@ -23,7 +23,7 @@ namespace Squidex.Domain.Apps.Entities.MongoDb.Assets
 {
     public sealed partial class MongoAssetFolderRepository : ISnapshotStore<AssetFolderDomainObject.State>
     {
-        async Task<(AssetFolderDomainObject.State Value, long Version)> ISnapshotStore<AssetFolderDomainObject.State>.ReadAsync(DomainId key)
+        async Task<(AssetFolderDomainObject.State Value, bool Valid, long Version)> ISnapshotStore<AssetFolderDomainObject.State>.ReadAsync(DomainId key)
         {
             using (Profiler.TraceMethod<MongoAssetFolderRepository>())
             {
@@ -33,10 +33,10 @@ namespace Squidex.Domain.Apps.Entities.MongoDb.Assets
 
                 if (existing != null)
                 {
-                    return (Map(existing), existing.Version);
+                    return (Map(existing), true, existing.Version);
                 }
 
-                return (null!, EtagVersion.Empty);
+                return (null!, true, EtagVersion.Empty);
             }
         }
 

backend/src/Squidex.Domain.Apps.Entities.MongoDb/Assets/MongoAssetRepository_SnapshotStore.cs

@@ -23,7 +23,7 @@ namespace Squidex.Domain.Apps.Entities.MongoDb.Assets
 {
     public sealed partial class MongoAssetRepository : ISnapshotStore<AssetDomainObject.State>
     {
-        async Task<(AssetDomainObject.State Value, long Version)> ISnapshotStore<AssetDomainObject.State>.ReadAsync(DomainId key)
+        async Task<(AssetDomainObject.State Value, bool Valid, long Version)> ISnapshotStore<AssetDomainObject.State>.ReadAsync(DomainId key)
         {
             using (Profiler.TraceMethod<MongoAssetRepository>())
             {
@@ -33,10 +33,10 @@ namespace Squidex.Domain.Apps.Entities.MongoDb.Assets
 
                 if (existing != null)
                 {
-                    return (Map(existing), existing.Version);
+                    return (Map(existing), true, existing.Version);
                 }
 
-                return (null!, EtagVersion.Empty);
+                return (null!, true, EtagVersion.Empty);
             }
         }
 

backend/src/Squidex.Domain.Apps.Entities.MongoDb/Contents/MongoContentCollection.cs

@@ -168,9 +168,11 @@ namespace Squidex.Domain.Apps.Entities.MongoDb.Contents
             }
         }
 
-        public Task<MongoContentEntity> FindAsync(DomainId documentId)
+        public async Task<long> FindVersionAsync(DomainId documentId)
         {
-            return Collection.Find(x => x.DocumentId == documentId).FirstOrDefaultAsync();
+            var result = await Collection.Find(x => x.DocumentId == documentId).Only(x => x.Version).FirstOrDefaultAsync();
+
+            return result?["vs"].AsInt64 ?? EtagVersion.Empty;
         }
 
         public Task ResetScheduledAsync(DomainId documentId)

backend/src/Squidex.Domain.Apps.Entities.MongoDb/Contents/MongoContentRepository_SnapshotStore.cs

@@ -23,12 +23,17 @@ namespace Squidex.Domain.Apps.Entities.MongoDb.Contents
     {
         Task ISnapshotStore<ContentDomainObject.State>.ReadAllAsync(Func<ContentDomainObject.State, long, Task> callback, CancellationToken ct)
         {
-            throw new NotSupportedException();
+            return Task.CompletedTask;
         }
 
-        Task<(ContentDomainObject.State Value, long Version)> ISnapshotStore<ContentDomainObject.State>.ReadAsync(DomainId key)
+        async Task<(ContentDomainObject.State Value, bool Valid, long Version)> ISnapshotStore<ContentDomainObject.State>.ReadAsync(DomainId key)
         {
-            return Task.FromResult<(ContentDomainObject.State, long Version)>((null!, EtagVersion.Empty));
+            using (Profiler.TraceMethod<MongoContentRepository>())
+            {
+                var version = await collectionAll.FindVersionAsync(key);
+
+                return (null!, false, version);
+            }
         }
 
         async Task ISnapshotStore<ContentDomainObject.State>.ClearAsync()

backend/src/Squidex.Domain.Apps.Entities/Assets/DomainObject/Guards/GuardAsset.cs

@@ -47,7 +47,7 @@ namespace Squidex.Domain.Apps.Entities.Assets.DomainObject.Guards
 
                 if (hasReferrer)
                 {
-                    throw new DomainException(T.Get("assets.referenced"));
+                    throw new DomainException(T.Get("assets.referenced"), "OBJECT_REFERENCED");
                 }
             }
         }

backend/src/Squidex.Domain.Apps.Entities/Contents/DomainObject/Guards/ValidationExtensions.cs

@@ -98,7 +98,7 @@ namespace Squidex.Domain.Apps.Entities.Contents.DomainObject.Guards
 
             if (hasReferrer)
             {
-                throw new DomainException(T.Get("contents.referenced"));
+                throw new DomainException(T.Get("contents.referenced", "OBJECT_REFERENCED"));
             }
         }
 

backend/src/Squidex.Domain.Users/DefaultKeyStore.cs

@@ -60,7 +60,7 @@ namespace Squidex.Domain.Users
                 return (cachedKeyInfo, cachedKey);
             }
 
-            var (state, _) = await store.ReadAsync(default);
+            var (state, _, _) = await store.ReadAsync(default);
 
             RsaSecurityKey securityKey;
 
@@ -92,7 +92,7 @@ namespace Squidex.Domain.Users
                 }
                 catch (InconsistentStateException)
                 {
-                    (state, _) = await store.ReadAsync(default);
+                    (state, _, _) = await store.ReadAsync(default);
                 }
             }
 

backend/src/Squidex.Infrastructure.MongoDb/States/MongoSnapshotStore.cs

@@ -43,7 +43,7 @@ namespace Squidex.Infrastructure.States
             return $"States_{name}";
         }
 
-        public async Task<(T Value, long Version)> ReadAsync(DomainId key)
+        public async Task<(T Value, bool Valid, long Version)> ReadAsync(DomainId key)
         {
             using (Profiler.TraceMethod<MongoSnapshotStore<T>>())
             {
@@ -53,10 +53,10 @@ namespace Squidex.Infrastructure.States
 
                 if (existing != null)
                 {
-                    return (existing.Doc, existing.Version);
+                    return (existing.Doc, true, existing.Version);
                 }
 
-                return (default!, EtagVersion.Empty);
+                return (default!, true, EtagVersion.Empty);
             }
         }
 

backend/src/Squidex.Infrastructure/DomainException.cs

@@ -13,14 +13,30 @@ namespace Squidex.Infrastructure
     [Serializable]
     public class DomainException : Exception
     {
+        public string? ErrorCode { get; }
+
         public DomainException(string message, Exception? inner = null)
             : base(message, inner)
         {
         }
 
+        public DomainException(string message, string? errorCode, Exception? inner = null)
+            : base(message, inner)
+        {
+            ErrorCode = errorCode;
+        }
+
         protected DomainException(SerializationInfo info, StreamingContext context)
             : base(info, context)
         {
+            ErrorCode = info.GetString(nameof(ErrorCode));
+        }
+
+        public override void GetObjectData(SerializationInfo info, StreamingContext context)
+        {
+            info.AddValue(nameof(ErrorCode), ErrorCode);
+
+            base.GetObjectData(info, context);
         }
     }
 }

backend/src/Squidex.Infrastructure/DomainForbiddenException.cs

@@ -13,8 +13,10 @@ namespace Squidex.Infrastructure
     [Serializable]
     public class DomainForbiddenException : DomainException
     {
+        private const string ValidationError = "FORBIDDEN";
+
         public DomainForbiddenException(string message, Exception? inner = null)
-            : base(message, inner)
+            : base(message, ValidationError, inner)
         {
         }
 

backend/src/Squidex.Infrastructure/DomainObjectConflictException.cs

@@ -14,8 +14,10 @@ namespace Squidex.Infrastructure
     [Serializable]
     public class DomainObjectConflictException : DomainObjectException
     {
+        private const string ValidationError = "OBJECT_CONFLICT";
+
         public DomainObjectConflictException(string id, Exception? inner = null)
-            : base(FormatMessage(id), id, inner)
+            : base(FormatMessage(id), id, ValidationError, inner)
         {
         }
 

backend/src/Squidex.Infrastructure/DomainObjectDeletedException.cs

@@ -14,8 +14,10 @@ namespace Squidex.Infrastructure
     [Serializable]
     public class DomainObjectDeletedException : DomainObjectException
     {
+        private const string ValidationError = "OBJECT_DELETED";
+
         public DomainObjectDeletedException(string id, Exception? inner = null)
-            : base(FormatMessage(id), id, inner)
+            : base(FormatMessage(id), id, ValidationError, inner)
         {
         }
 

backend/src/Squidex.Infrastructure/DomainObjectException.cs

@@ -15,8 +15,8 @@ namespace Squidex.Infrastructure
     {
         public string Id { get; }
 
-        public DomainObjectException(string message, string id, Exception? inner = null)
+        public DomainObjectException(string message, string id, string errorCode, Exception? inner = null)
-            : base(message, inner)
+            : base(message, errorCode, inner)
         {
             Guard.NotNullOrEmpty(id, nameof(id));
 

backend/src/Squidex.Infrastructure/DomainObjectNotFoundException.cs

@@ -14,8 +14,10 @@ namespace Squidex.Infrastructure
     [Serializable]
     public class DomainObjectNotFoundException : DomainObjectException
     {
+        private const string ValidationError = "OBJECT_NOTFOUND";
+
         public DomainObjectNotFoundException(string id, Exception? inner = null)
-            : base(FormatMessage(id), id, inner)
+            : base(FormatMessage(id), id, ValidationError, inner)
         {
         }
 

backend/src/Squidex.Infrastructure/DomainObjectVersionException.cs

@@ -14,12 +14,14 @@ namespace Squidex.Infrastructure
     [Serializable]
     public class DomainObjectVersionException : DomainObjectException
     {
+        private const string ValidationError = "OBJECT_VERSION_CONFLICT";
+
         public long CurrentVersion { get; }
 
         public long ExpectedVersion { get; }
 
         public DomainObjectVersionException(string id, long currentVersion, long expectedVersion, Exception? inner = null)
-            : base(FormatMessage(id, currentVersion, expectedVersion), id, inner)
+            : base(FormatMessage(id, currentVersion, expectedVersion), id, ValidationError, inner)
         {
             CurrentVersion = currentVersion;
 

backend/src/Squidex.Infrastructure/States/ISnapshotStore.cs

@@ -18,7 +18,7 @@ namespace Squidex.Infrastructure.States
 
         Task WriteManyAsync(IEnumerable<(DomainId Key, T Value, long Version)> snapshots);
 
-        Task<(T Value, long Version)> ReadAsync(DomainId key);
+        Task<(T Value, bool Valid, long Version)> ReadAsync(DomainId key);
 
         Task ClearAsync();
 

backend/src/Squidex.Infrastructure/States/Persistence.cs

@@ -46,7 +46,7 @@ namespace Squidex.Infrastructure.States
 
         public bool IsSnapshotStale
         {
-            get => persistenceMode == PersistenceMode.SnapshotsAndEventSourcing && versionSnapshot < versionEvents && versionSnapshot > EtagVersion.Empty;
+            get => UseSnapshots && UseEventSourcing && versionSnapshot < versionEvents;
         }
 
         public Persistence(DomainId ownerKey, Type ownerType,
@@ -114,14 +114,17 @@ namespace Squidex.Infrastructure.States
 
         private async Task ReadSnapshotAsync()
         {
-            var (state, version) = await snapshotStore.ReadAsync(ownerKey);
+            var (state, valid, version) = await snapshotStore.ReadAsync(ownerKey);
 
             version = Math.Max(version, EtagVersion.Empty);
-
             versionSnapshot = version;
+
+            if (valid)
+            {
                 versionEvents = version;
+            }
 
-            if (applyState != null && version >= 0)
+            if (applyState != null && version > EtagVersion.Empty && valid)
             {
                 applyState(state, version);
             }
@@ -162,7 +165,7 @@ namespace Squidex.Infrastructure.States
 
             if (oldVersion == EtagVersion.Empty && UseEventSourcing)
             {
-                oldVersion = (versionEvents - 1);
+                oldVersion = versionEvents - 1;
             }
 
             var newVersion = UseEventSourcing ? versionEvents : oldVersion + 1;

backend/src/Squidex.Infrastructure/Validation/ValidationException.cs

@@ -15,6 +15,8 @@ namespace Squidex.Infrastructure.Validation
     [Serializable]
     public class ValidationException : DomainException
     {
+        private const string ValidationError = "VALIDATION_ERROR";
+
         public IReadOnlyList<ValidationError> Errors { get; }
 
         public ValidationException(string error, Exception? inner = null)
@@ -28,7 +30,7 @@ namespace Squidex.Infrastructure.Validation
         }
 
         public ValidationException(IReadOnlyList<ValidationError> errors, Exception? inner = null)
-            : base(FormatMessage(errors), inner)
+            : base(FormatMessage(errors), ValidationError, inner)
         {
             Errors = errors;
         }

backend/src/Squidex.Web/ApiExceptionConverter.cs

@@ -29,6 +29,7 @@ namespace Squidex.Web
             [404] = "https://tools.ietf.org/html/rfc7231#section-6.5.4",
             [406] = "https://tools.ietf.org/html/rfc7231#section-6.5.6",
             [409] = "https://tools.ietf.org/html/rfc7231#section-6.5.8",
+            [410] = "https://tools.ietf.org/html/rfc7231#section-6.5.9",
             [412] = "https://tools.ietf.org/html/rfc7231#section-6.5.10",
             [415] = "https://tools.ietf.org/html/rfc7231#section-6.5.13",
             [422] = "https://tools.ietf.org/html/rfc4918#section-11.2",
@@ -85,20 +86,23 @@ namespace Squidex.Web
                 case ValidationException ex:
                     return (CreateError(400, T.Get("common.httpValidationError"), ToErrors(ex.Errors).ToArray()), true);
 
-                case DomainObjectNotFoundException:
+                case DomainObjectNotFoundException ex:
-                    return (CreateError(404), true);
+                    return (CreateError(404, errorCode: ex.ErrorCode), true);
 
-                case DomainObjectVersionException:
+                case DomainObjectVersionException ex:
-                    return (CreateError(412, exception.Message), true);
+                    return (CreateError(412, exception.Message, errorCode: ex.ErrorCode), true);
 
-                case DomainObjectConflictException:
+                case DomainObjectDeletedException ex:
-                    return (CreateError(409, exception.Message), true);
+                    return (CreateError(410, exception.Message, errorCode: ex.ErrorCode), true);
 
-                case DomainForbiddenException:
+                case DomainObjectConflictException ex:
-                    return (CreateError(403, exception.Message), true);
+                    return (CreateError(409, exception.Message, errorCode: ex.ErrorCode), true);
 
-                case DomainException:
+                case DomainForbiddenException ex:
-                    return (CreateError(400, exception.Message), true);
+                    return (CreateError(403, exception.Message, errorCode: ex.ErrorCode), true);
+
+                case DomainException ex:
+                    return (CreateError(400, exception.Message, errorCode: ex.ErrorCode), true);
 
                 case SecurityException:
                     return (CreateError(403), false);
@@ -114,9 +118,9 @@ namespace Squidex.Web
             }
         }
 
-        private static ErrorDto CreateError(int status, string? message = null, string[]? details = null)
+        private static ErrorDto CreateError(int status, string? message = null, string[]? details = null, string? errorCode = null)
         {
-            var error = new ErrorDto { StatusCode = status, Message = message, Details = details };
+            var error = new ErrorDto { StatusCode = status, Message = message, Details = details, ErrorCode = errorCode };
 
             return error;
         }

backend/src/Squidex.Web/ErrorDto.cs

@@ -16,6 +16,9 @@ namespace Squidex.Web
         [Display(Description = "Error message.")]
         public string? Message { get; set; }
 
+        [Display(Description = "The error code.")]
+        public string? ErrorCode { get; set; }
+
         [Display(Description = "The optional trace id.")]
         public string? TraceId { get; set; }
 

backend/tests/Squidex.Domain.Users.Tests/DefaultKeyStoreTests.cs

@@ -27,7 +27,7 @@ namespace Squidex.Domain.Users
         public async Task Should_generate_signing_credentials_once()
         {
             A.CallTo(() => store.ReadAsync(A<DomainId>._))
-                .Returns((null!, 0));
+                .Returns((null!, true, 0));
 
             var credentials1 = await sut.GetSigningCredentialsAsync();
             var credentials2 = await sut.GetSigningCredentialsAsync();
@@ -45,7 +45,7 @@ namespace Squidex.Domain.Users
         public async Task Should_generate_validation_keys_once()
         {
             A.CallTo(() => store.ReadAsync(A<DomainId>._))
-                .Returns((null!, 0));
+                .Returns((null!, true, 0));
 
             var credentials1 = await sut.GetValidationKeysAsync();
             var credentials2 = await sut.GetValidationKeysAsync();

backend/tests/Squidex.Infrastructure.Tests/Commands/DomainObjectTests.cs

@@ -35,6 +35,34 @@ namespace Squidex.Infrastructure.Commands
             AssertSnapshot(sut.Snapshot, 0, EtagVersion.Empty);
         }
 
+        [Fact]
+        public async Task Should_repair_when_stale()
+        {
+            A.CallTo(() => persistence.IsSnapshotStale)
+                .Returns(true);
+
+            SetupCreated(1);
+
+            await sut.EnsureLoadedAsync();
+
+            A.CallTo(() => persistence.WriteSnapshotAsync(A<MyDomainState>._))
+                .MustHaveHappened();
+        }
+
+        [Fact]
+        public async Task Should_not_repair_when_not_stale()
+        {
+            A.CallTo(() => persistence.IsSnapshotStale)
+                .Returns(false);
+
+            SetupCreated(1);
+
+            await sut.EnsureLoadedAsync();
+
+            A.CallTo(() => persistence.WriteSnapshotAsync(A<MyDomainState>._))
+                .MustNotHaveHappened();
+        }
+
         [Fact]
         public async Task Should_write_state_and_events_when_created()
         {

backend/tests/Squidex.Infrastructure.Tests/DomainObjectExceptionTests.cs

@@ -12,6 +12,16 @@ namespace Squidex.Infrastructure
 {
     public class DomainObjectExceptionTests
     {
+        [Fact]
+        public void Should_serialize_and_deserialize_DomainException()
+        {
+            var source = new DomainException("Message", "ErrorCode");
+            var result = source.SerializeAndDeserializeBinary();
+
+            Assert.Equal(result.ErrorCode, source.ErrorCode);
+            Assert.Equal(result.Message, source.Message);
+        }
+
         [Fact]
         public void Should_serialize_and_deserialize_DomainObjectDeletedException()
         {
@@ -19,7 +29,6 @@ namespace Squidex.Infrastructure
             var result = source.SerializeAndDeserializeBinary();
 
             Assert.Equal(result.Id, source.Id);
-
             Assert.Equal(result.Message, source.Message);
         }
 
@@ -30,7 +39,6 @@ namespace Squidex.Infrastructure
             var result = source.SerializeAndDeserializeBinary();
 
             Assert.Equal(result.Id, source.Id);
-
             Assert.Equal(result.Message, source.Message);
         }
 
@@ -43,7 +51,6 @@ namespace Squidex.Infrastructure
             Assert.Equal(result.Id, source.Id);
             Assert.Equal(result.ExpectedVersion, source.ExpectedVersion);
             Assert.Equal(result.CurrentVersion, source.CurrentVersion);
-
             Assert.Equal(result.Message, source.Message);
         }
     }

backend/tests/Squidex.Infrastructure.Tests/States/PersistenceEventSourcingTests.cs

@@ -19,18 +19,18 @@ namespace Squidex.Infrastructure.States
     public class PersistenceEventSourcingTests
     {
         private readonly DomainId key = DomainId.NewGuid();
-        private readonly ISnapshotStore<int> snapshotStore = A.Fake<ISnapshotStore<int>>();
+        private readonly ISnapshotStore<string> snapshotStore = A.Fake<ISnapshotStore<string>>();
         private readonly IEventDataFormatter eventDataFormatter = A.Fake<IEventDataFormatter>();
         private readonly IEventStore eventStore = A.Fake<IEventStore>();
         private readonly IStreamNameResolver streamNameResolver = A.Fake<IStreamNameResolver>();
-        private readonly IStore<int> sut;
+        private readonly IStore<string> sut;
 
         public PersistenceEventSourcingTests()
         {
             A.CallTo(() => streamNameResolver.GetStreamName(None.Type, A<string>._))
                 .ReturnsLazily(x => x.GetArgument<string>(1)!);
 
-            sut = new Store<int>(snapshotStore, eventStore, eventDataFormatter, streamNameResolver);
+            sut = new Store<string>(snapshotStore, eventStore, eventDataFormatter, streamNameResolver);
         }
 
         [Fact]
@@ -86,32 +86,54 @@ namespace Squidex.Infrastructure.States
         }
 
         [Fact]
-        public async Task Should_read_status_from_snapshot()
+        public async Task Should_read_read_from_snapshot_store()
         {
             A.CallTo(() => snapshotStore.ReadAsync(key))
-                .Returns((2, 2L));
+                .Returns(("2", true, 2L));
 
             SetupEventStore(3, 2);
 
-            var persistedState = Save.Snapshot(-1);
+            var persistedState = Save.Snapshot(string.Empty);
             var persistedEvents = Save.Events();
             var persistence = sut.WithSnapshotsAndEventSourcing(None.Type, key, persistedState.Write, persistedEvents.Write);
 
             await persistence.ReadAsync();
 
+            Assert.False(persistence.IsSnapshotStale);
+
             A.CallTo(() => eventStore.QueryAsync(key.ToString(), 3))
                 .MustHaveHappened();
         }
 
+        [Fact]
+        public async Task Should_mark_as_stale_when_snapshot_old_than_events()
+        {
+            A.CallTo(() => snapshotStore.ReadAsync(key))
+                .Returns(("2", true, 1L));
+
+            SetupEventStore(3, 2, 2);
+
+            var persistedState = Save.Snapshot(string.Empty);
+            var persistedEvents = Save.Events();
+            var persistence = sut.WithSnapshotsAndEventSourcing(None.Type, key, persistedState.Write, persistedEvents.Write);
+
+            await persistence.ReadAsync();
+
+            Assert.True(persistence.IsSnapshotStale);
+
+            A.CallTo(() => eventStore.QueryAsync(key.ToString(), 2))
+                .MustHaveHappened();
+        }
+
         [Fact]
         public async Task Should_throw_exception_if_events_are_older_than_snapshot()
         {
             A.CallTo(() => snapshotStore.ReadAsync(key))
-                .Returns((2, 2L));
+                .Returns(("2", true, 2L));
 
             SetupEventStore(3, 0, 3);
 
-            var persistedState = Save.Snapshot(-1);
+            var persistedState = Save.Snapshot(string.Empty);
             var persistedEvents = Save.Events();
             var persistence = sut.WithSnapshotsAndEventSourcing(None.Type, key, persistedState.Write, persistedEvents.Write);
 
@@ -122,11 +144,11 @@ namespace Squidex.Infrastructure.States
         public async Task Should_throw_exception_if_events_have_gaps_to_snapshot()
         {
             A.CallTo(() => snapshotStore.ReadAsync(key))
-                .Returns((2, 2L));
+                .Returns(("2", true, 2L));
 
             SetupEventStore(3, 4, 3);
 
-            var persistedState = Save.Snapshot(-1);
+            var persistedState = Save.Snapshot(string.Empty);
             var persistedEvents = Save.Events();
             var persistence = sut.WithSnapshotsAndEventSourcing(None.Type, key, persistedState.Write, persistedEvents.Write);
 
@@ -159,11 +181,11 @@ namespace Squidex.Infrastructure.States
         public async Task Should_throw_exception_if_other_version_found_from_snapshot()
         {
             A.CallTo(() => snapshotStore.ReadAsync(key))
-                .Returns((2, 2L));
+                .Returns(("2", true, 2L));
 
             SetupEventStore(0);
 
-            var persistedState = Save.Snapshot(-1);
+            var persistedState = Save.Snapshot(string.Empty);
             var persistedEvents = Save.Events();
             var persistence = sut.WithSnapshotsAndEventSourcing(None.Type, key, persistedState.Write, persistedEvents.Write);
 
@@ -175,7 +197,7 @@ namespace Squidex.Infrastructure.States
         {
             SetupEventStore(0);
 
-            var persistedState = Save.Snapshot(-1);
+            var persistedState = Save.Snapshot(string.Empty);
             var persistedEvents = Save.Events();
             var persistence = sut.WithSnapshotsAndEventSourcing(None.Type, key, persistedState.Write, persistedEvents.Write);
 
@@ -200,7 +222,7 @@ namespace Squidex.Infrastructure.States
             A.CallTo(() => eventStore.AppendAsync(A<Guid>._, key.ToString(), 3, A<ICollection<EventData>>.That.Matches(x => x.Count == 1)))
                 .MustHaveHappened();
 
-            A.CallTo(() => snapshotStore.WriteAsync(A<DomainId>._, A<int>._, A<long>._, A<long>._))
+            A.CallTo(() => snapshotStore.WriteAsync(A<DomainId>._, A<string>._, A<long>._, A<long>._))
                 .MustNotHaveHappened();
         }
 
@@ -219,25 +241,25 @@ namespace Squidex.Infrastructure.States
         public async Task Should_write_snapshot_to_store()
         {
             A.CallTo(() => snapshotStore.ReadAsync(key))
-                .Returns((2, 2L));
+                .Returns(("2", true, 2L));
 
             SetupEventStore(3);
 
-            var persistedState = Save.Snapshot(-1);
+            var persistedState = Save.Snapshot(string.Empty);
             var persistedEvents = Save.Events();
             var persistence = sut.WithSnapshotsAndEventSourcing(None.Type, key, persistedState.Write, persistedEvents.Write);
 
             await persistence.ReadAsync();
 
             await persistence.WriteEventAsync(Envelope.Create(new MyEvent()));
-            await persistence.WriteSnapshotAsync(4);
+            await persistence.WriteSnapshotAsync("4");
 
             await persistence.WriteEventAsync(Envelope.Create(new MyEvent()));
-            await persistence.WriteSnapshotAsync(5);
+            await persistence.WriteSnapshotAsync("5");
 
-            A.CallTo(() => snapshotStore.WriteAsync(key, 4, 2, 3))
+            A.CallTo(() => snapshotStore.WriteAsync(key, "4", 2, 3))
                 .MustHaveHappened();
-            A.CallTo(() => snapshotStore.WriteAsync(key, 5, 3, 4))
+            A.CallTo(() => snapshotStore.WriteAsync(key, "5", 3, 4))
                 .MustHaveHappened();
         }
 
@@ -245,25 +267,25 @@ namespace Squidex.Infrastructure.States
         public async Task Should_write_snapshot_to_store_when_not_read_before()
         {
             A.CallTo(() => snapshotStore.ReadAsync(key))
-                .Returns((default, EtagVersion.Empty));
+                .Returns((null!, true, EtagVersion.Empty));
 
             SetupEventStore(3);
 
-            var persistedState = Save.Snapshot(-1);
+            var persistedState = Save.Snapshot(string.Empty);
             var persistedEvents = Save.Events();
             var persistence = sut.WithSnapshotsAndEventSourcing(None.Type, key, persistedState.Write, persistedEvents.Write);
 
             await persistence.ReadAsync();
 
             await persistence.WriteEventAsync(Envelope.Create(new MyEvent()));
-            await persistence.WriteSnapshotAsync(4);
+            await persistence.WriteSnapshotAsync("4");
 
             await persistence.WriteEventAsync(Envelope.Create(new MyEvent()));
-            await persistence.WriteSnapshotAsync(5);
+            await persistence.WriteSnapshotAsync("5");
 
-            A.CallTo(() => snapshotStore.WriteAsync(key, 4, 2, 3))
+            A.CallTo(() => snapshotStore.WriteAsync(key, "4", 2, 3))
                 .MustHaveHappened();
-            A.CallTo(() => snapshotStore.WriteAsync(key, 5, 3, 4))
+            A.CallTo(() => snapshotStore.WriteAsync(key, "5", 3, 4))
                 .MustHaveHappened();
         }
 
@@ -271,19 +293,19 @@ namespace Squidex.Infrastructure.States
         public async Task Should_not_write_snapshot_to_store_when_not_changed()
         {
             A.CallTo(() => snapshotStore.ReadAsync(key))
-                .Returns((0, 2));
+                .Returns(("0", true, 2));
 
             SetupEventStore(3);
 
-            var persistedState = Save.Snapshot(-1);
+            var persistedState = Save.Snapshot(string.Empty);
             var persistedEvents = Save.Events();
             var persistence = sut.WithSnapshotsAndEventSourcing(None.Type, key, persistedState.Write, persistedEvents.Write);
 
             await persistence.ReadAsync();
 
-            await persistence.WriteSnapshotAsync(4);
+            await persistence.WriteSnapshotAsync("4");
 
-            A.CallTo(() => snapshotStore.WriteAsync(key, A<int>._, A<long>._, A<long>._))
+            A.CallTo(() => snapshotStore.WriteAsync(key, A<string>._, A<long>._, A<long>._))
                 .MustNotHaveHappened();
         }
 

backend/tests/Squidex.Infrastructure.Tests/States/PersistenceSnapshotTests.cs

@@ -31,7 +31,7 @@ namespace Squidex.Infrastructure.States
         public async Task Should_read_from_store()
         {
             A.CallTo(() => snapshotStore.ReadAsync(key))
-                .Returns((20, 10));
+                .Returns((20, true, 10));
 
             var persistedState = Save.Snapshot(0);
             var persistence = sut.WithSnapshots(None.Type, key, persistedState.Write);
@@ -42,11 +42,26 @@ namespace Squidex.Infrastructure.States
             Assert.Equal(20, persistedState.Value);
         }
 
+        [Fact]
+        public async Task Should_not_read_from_store_when_not_valid()
+        {
+            A.CallTo(() => snapshotStore.ReadAsync(key))
+                .Returns((20, false, 10));
+
+            var persistedState = Save.Snapshot(0);
+            var persistence = sut.WithSnapshots(None.Type, key, persistedState.Write);
+
+            await persistence.ReadAsync();
+
+            Assert.Equal(10, persistence.Version);
+            Assert.Equal(0, persistedState.Value);
+        }
+
         [Fact]
         public async Task Should_return_empty_version_when_version_negative()
         {
             A.CallTo(() => snapshotStore.ReadAsync(key))
-                .Returns((20, -10));
+                .Returns((20, true, -10));
 
             var persistedState = Save.Snapshot(0);
             var persistence = sut.WithSnapshots(None.Type, key, persistedState.Write);
@@ -60,7 +75,7 @@ namespace Squidex.Infrastructure.States
         public async Task Should_set_to_empty_when_store_returns_not_found()
         {
             A.CallTo(() => snapshotStore.ReadAsync(key))
-                .Returns((20, EtagVersion.Empty));
+                .Returns((20, true, EtagVersion.Empty));
 
             var persistedState = Save.Snapshot(0);
             var persistence = sut.WithSnapshots(None.Type, key, persistedState.Write);
@@ -75,7 +90,7 @@ namespace Squidex.Infrastructure.States
         public async Task Should_throw_exception_if_not_found_and_version_expected()
         {
             A.CallTo(() => snapshotStore.ReadAsync(key))
-                .Returns((123, EtagVersion.Empty));
+                .Returns((123, true, EtagVersion.Empty));
 
             var persistedState = Save.Snapshot(0);
             var persistence = sut.WithSnapshots(None.Type, key, persistedState.Write);
@@ -87,7 +102,7 @@ namespace Squidex.Infrastructure.States
         public async Task Should_throw_exception_if_other_version_found()
         {
             A.CallTo(() => snapshotStore.ReadAsync(key))
-                .Returns((123, 2));
+                .Returns((123, true, 2));
 
             var persistedState = Save.Snapshot(0);
             var persistence = sut.WithSnapshots(None.Type, key, persistedState.Write);
@@ -99,7 +114,7 @@ namespace Squidex.Infrastructure.States
         public async Task Should_write_to_store_with_previous_version()
         {
             A.CallTo(() => snapshotStore.ReadAsync(key))
-                .Returns((20, 10));
+                .Returns((20, true, 10));
 
             var persistedState = Save.Snapshot(0);
             var persistence = sut.WithSnapshots(None.Type, key, persistedState.Write);
@@ -130,7 +145,7 @@ namespace Squidex.Infrastructure.States
         public async Task Should_not_wrap_exception_when_writing_to_store_with_previous_version()
         {
             A.CallTo(() => snapshotStore.ReadAsync(key))
-                .Returns((20, 10));
+                .Returns((20, true, 10));
 
             A.CallTo(() => snapshotStore.WriteAsync(key, 100, 10, 11))
                 .Throws(new InconsistentStateException(1, 1, new InvalidOperationException()));

backend/tests/Squidex.Web.Tests/ApiExceptionFilterAttributeTests.cs

@@ -103,6 +103,19 @@ namespace Squidex.Web
                 .MustNotHaveHappened();
         }
 
+        [Fact]
+        public void Should_generate_400_for_DomainException_with_error_code()
+        {
+            var context = Error(new DomainException("NotAllowed", "ERROR_CODE_XYZ"));
+
+            sut.OnException(context);
+
+            Validate(400, context.Result, context.Exception, "ERROR_CODE_XYZ");
+
+            A.CallTo(() => log.Log(A<SemanticLogLevel>._, A<Exception?>._, A<LogFormatter>._!))
+                .MustNotHaveHappened();
+        }
+
         [Fact]
         public void Should_generate_400_for_DecoderFallbackException()
         {
@@ -123,7 +136,20 @@ namespace Squidex.Web
 
             sut.OnException(context);
 
-            Validate(409, context.Result, context.Exception);
+            Validate(409, context.Result, context.Exception, "OBJECT_CONFLICT");
+
+            A.CallTo(() => log.Log(A<SemanticLogLevel>._, A<Exception?>._, A<LogFormatter>._!))
+                .MustNotHaveHappened();
+        }
+
+        [Fact]
+        public void Should_generate_410_for_DomainObjectDeletedException()
+        {
+            var context = Error(new DomainObjectDeletedException("1"));
+
+            sut.OnException(context);
+
+            Validate(410, context.Result, context.Exception, "OBJECT_DELETED");
 
             A.CallTo(() => log.Log(A<SemanticLogLevel>._, A<Exception?>._, A<LogFormatter>._!))
                 .MustNotHaveHappened();
@@ -136,7 +162,7 @@ namespace Squidex.Web
 
             sut.OnException(context);
 
-            Validate(412, context.Result, context.Exception);
+            Validate(412, context.Result, context.Exception, "OBJECT_VERSION_CONFLICT");
 
             A.CallTo(() => log.Log(A<SemanticLogLevel>._, A<Exception?>._, A<LogFormatter>._!))
                 .MustNotHaveHappened();
@@ -149,7 +175,7 @@ namespace Squidex.Web
 
             sut.OnException(context);
 
-            Validate(403, context.Result, context.Exception);
+            Validate(403, context.Result, context.Exception, "FORBIDDEN");
 
             A.CallTo(() => log.Log(A<SemanticLogLevel>._, A<Exception?>._, A<LogFormatter>._!))
                 .MustNotHaveHappened();
@@ -229,7 +255,7 @@ namespace Squidex.Web
             return actionContext;
         }
 
-        private static void Validate(int statusCode, IActionResult? actionResult, Exception? exception)
+        private static void Validate(int statusCode, IActionResult? actionResult, Exception? exception, string? errorCode = null)
         {
             var result = actionResult as ObjectResult;
 
@@ -239,6 +265,7 @@ namespace Squidex.Web
 
             Assert.Equal(statusCode, result?.StatusCode);
             Assert.Equal(statusCode, error?.StatusCode);
+            Assert.Equal(errorCode, error?.ErrorCode);
 
             if (exception != null)
             {

frontend/app/framework/angular/forms/error-validator.spec.ts

@@ -33,7 +33,7 @@ describe('ErrorValidator', () => {
     });
 
     it('should return no message when error does not match', () => {
-        validator.setError(new ErrorDto(500, 'Error', [
+        validator.setError(new ErrorDto(500, 'Error', null, [
             'nested1Property: My Error.'
         ]));
 
@@ -43,7 +43,7 @@ describe('ErrorValidator', () => {
     });
 
     it('should return matching error', () => {
-        validator.setError(new ErrorDto(500, 'Error', [
+        validator.setError(new ErrorDto(500, 'Error', null, [
             'other, nested1: My Error.'
         ]));
 
@@ -57,7 +57,7 @@ describe('ErrorValidator', () => {
     });
 
     it('should return matching error twice if value does not change', () => {
-        validator.setError(new ErrorDto(500, 'Error', [
+        validator.setError(new ErrorDto(500, 'Error', null, [
             'nested1: My Error.'
         ]));
 
@@ -78,7 +78,7 @@ describe('ErrorValidator', () => {
     });
 
     it('should not return matching error again if value has changed', () => {
-        validator.setError(new ErrorDto(500, 'Error', [
+        validator.setError(new ErrorDto(500, 'Error', null, [
             'nested1[1].nested2: My Error.'
         ]));
 
@@ -100,7 +100,7 @@ describe('ErrorValidator', () => {
     });
 
     it('should not return matching error again if value has changed to initial', () => {
-        validator.setError(new ErrorDto(500, 'Error', [
+        validator.setError(new ErrorDto(500, 'Error', null, [
             'nested1[1].nested2: My Error.'
         ]));
 
@@ -126,7 +126,7 @@ describe('ErrorValidator', () => {
     });
 
     it('should return matching errors', () => {
-        validator.setError(new ErrorDto(500, 'Error', [
+        validator.setError(new ErrorDto(500, 'Error', null, [
             'nested1: My Error1.',
             'nested1: My Error2.'
         ]));
@@ -141,7 +141,7 @@ describe('ErrorValidator', () => {
     });
 
     it('should return deeply matching error', () => {
-        validator.setError(new ErrorDto(500, 'Error', [
+        validator.setError(new ErrorDto(500, 'Error', null, [
             'nested1[1].nested2: My Error.'
         ]));
 
@@ -155,7 +155,7 @@ describe('ErrorValidator', () => {
     });
 
     it('should return partial matching error', () => {
-        validator.setError(new ErrorDto(500, 'Error', [
+        validator.setError(new ErrorDto(500, 'Error', null, [
             'nested1[1].nested2: My Error.'
         ]));
 
@@ -169,7 +169,7 @@ describe('ErrorValidator', () => {
     });
 
     it('should return partial matching index error', () => {
-        validator.setError(new ErrorDto(500, 'Error', [
+        validator.setError(new ErrorDto(500, 'Error', null, [
             'nested1[1].nested2: My Error.'
         ]));
 

frontend/app/framework/angular/http/http-extensions.spec.ts

@@ -13,11 +13,11 @@ describe('ErrorParsing', () => {
         const response: any = new Error();
         const result = parseError(response, 'Fallback');
 
-        expect(result).toEqual(new ErrorDto(500, 'Fallback', [], response));
+        expect(result).toEqual(new ErrorDto(500, 'Fallback', null, [], response));
     });
 
     it('should just forward error dto', () => {
-        const response: any = new ErrorDto(500, 'error', []);
+        const response: any = new ErrorDto(500, 'error', null, []);
         const result = parseError(response, 'Fallback');
 
         expect(result).toBe(response);
@@ -27,23 +27,23 @@ describe('ErrorParsing', () => {
         const response: any = { status: 412 };
         const result = parseError(response, 'Fallback');
 
-        expect(result).toEqual(new ErrorDto(412, 'i18n:common.httpConflict', [], response));
+        expect(result).toEqual(new ErrorDto(412, 'i18n:common.httpConflict', null, [], response));
     });
 
     it('should return default 429 error', () => {
         const response: any = { status: 429 };
         const result = parseError(response, 'Fallback');
 
-        expect(result).toEqual(new ErrorDto(429, 'i18n:common.httpLimit', [], response));
+        expect(result).toEqual(new ErrorDto(429, 'i18n:common.httpLimit', null, [], response));
     });
 
     it('should return error from error object', () => {
-        const error = { message: 'My-Message', details: ['My-Detail'] };
+        const error = { message: 'My-Message', details: ['My-Detail'], errorCode: 'ERROR_CODE_XYZ' };
 
         const response: any = { status: 400, error };
         const result = parseError(response, 'Fallback');
 
-        expect(result).toEqual(new ErrorDto(400, 'My-Message', ['My-Detail'], response));
+        expect(result).toEqual(new ErrorDto(400, 'My-Message', 'ERROR_CODE_XYZ', ['My-Detail'], response));
     });
 
     it('should return error from error json', () => {
@@ -52,7 +52,7 @@ describe('ErrorParsing', () => {
         const response: any = { status: 400, error: JSON.stringify(error) };
         const result = parseError(response, 'Fallback');
 
-        expect(result).toEqual(new ErrorDto(400, 'My-Message', ['My-Detail'], response));
+        expect(result).toEqual(new ErrorDto(400, 'My-Message', undefined, ['My-Detail'], response));
     });
 
     it('should return default when object is invalid', () => {
@@ -61,7 +61,7 @@ describe('ErrorParsing', () => {
         const response: any = { status: 400, error };
         const result = parseError(response, 'Fallback');
 
-        expect(result).toEqual(new ErrorDto(500, 'Fallback', [], response));
+        expect(result).toEqual(new ErrorDto(500, 'Fallback', null, [], response));
     });
 
     it('should return default when json is invalid', () => {
@@ -70,6 +70,6 @@ describe('ErrorParsing', () => {
         const response: any = { status: 400, error };
         const result = parseError(response, 'Fallback');
 
-        expect(result).toEqual(new ErrorDto(500, 'Fallback', [], response));
+        expect(result).toEqual(new ErrorDto(500, 'Fallback', null, [], response));
     });
 });

frontend/app/framework/angular/http/http-extensions.ts

@@ -97,11 +97,11 @@ export function parseError(response: HttpErrorResponse, fallback: string) {
     const { error, status } = response;
 
     if (status === 412) {
-        return new ErrorDto(412, 'i18n:common.httpConflict', [], response);
+        return new ErrorDto(412, 'i18n:common.httpConflict', null, [], response);
     }
 
     if (status === 429) {
-        return new ErrorDto(429, 'i18n:common.httpLimit', [], response);
+        return new ErrorDto(429, 'i18n:common.httpLimit', null, [], response);
     }
 
     let parsed: any;
@@ -117,8 +117,8 @@ export function parseError(response: HttpErrorResponse, fallback: string) {
     }
 
     if (parsed && Types.isString(parsed.message)) {
-        return new ErrorDto(status, parsed.message, parsed.details, response);
+        return new ErrorDto(status, parsed.message, parsed.errorCode, parsed.details, response);
     }
 
-    return new ErrorDto(500, fallback, [], response);
+    return new ErrorDto(500, fallback, null, [], response);
 }

frontend/app/framework/utils/error.spec.ts

@@ -20,6 +20,12 @@ describe('ErrorDto', () => {
             .returns((key: string) => key.substr(5));
     });
 
+    it('should create simple message with error code', () => {
+        const error = new ErrorDto(500, 'i18n:error.', 'ERROR_CODE_XYZ');
+
+        expect(error.errorCode).toBe('ERROR_CODE_XYZ');
+    });
+
     it('should create simple message when no details are specified.', () => {
         const error = new ErrorDto(500, 'i18n:error.');
 
@@ -37,7 +43,7 @@ describe('ErrorDto', () => {
     });
 
     it('should append dot to detail', () => {
-        const error = new ErrorDto(500, 'i18n:error.', ['i18n:detail']);
+        const error = new ErrorDto(500, 'i18n:error.', null, ['i18n:detail']);
 
         const result = error.translate(localizer.object);
 
@@ -45,7 +51,7 @@ describe('ErrorDto', () => {
     });
 
     it('should ccreate html list when detail has one item', () => {
-        const error = new ErrorDto(500, 'i18n:error.', ['i18n:detail.']);
+        const error = new ErrorDto(500, 'i18n:error.', null, ['i18n:detail.']);
 
         const result = error.translate(localizer.object);
 
@@ -53,7 +59,7 @@ describe('ErrorDto', () => {
     });
 
     it('should create html list when error has more items.', () => {
-        const error = new ErrorDto(500, 'i18n:error.', ['i18n:detail1.', 'i18n:detail2.']);
+        const error = new ErrorDto(500, 'i18n:error.', null, ['i18n:detail1.', 'i18n:detail2.']);
 
         const result = error.translate(localizer.object);
 

frontend/app/framework/utils/error.ts

@@ -39,6 +39,7 @@ export class ErrorDto {
     constructor(
         public readonly statusCode: number,
         public readonly message: string,
+        public readonly errorCode?: string | null,
         details?: ReadonlyArray<string> | ReadonlyArray<ErrorDetailsDto>,
         public readonly inner?: any
     ) {

frontend/app/shared/state/assets.state.spec.ts

@@ -342,7 +342,7 @@ describe('AssetsState', () => {
 
         it('should remove asset from snapshot when when referenced and not confirmed', () => {
             assetsService.setup(x => x.deleteAssetItem(app, asset1, false, asset1.version))
-                .returns(() => throwError(new ErrorDto(404, 'Referenced')));
+                .returns(() => throwError(new ErrorDto(404, 'Referenced', 'OBJECT_REFERENCED')));
 
             assetsService.setup(x => x.deleteAssetItem(app, asset1, true, asset1.version))
                 .returns(() => of(versioned(newVersion)));
@@ -359,7 +359,7 @@ describe('AssetsState', () => {
 
         it('should not remove asset when referenced and not confirmed', () => {
             assetsService.setup(x => x.deleteAssetItem(app, asset1, true, asset1.version))
-                .returns(() => throwError(new ErrorDto(404, 'Referenced')));
+                .returns(() => throwError(new ErrorDto(404, 'Referenced', 'OBJECT_REFERENCED')));
 
             dialogs.setup(x => x.confirm(It.isAnyString(), It.isAnyString(), It.isAnyString()))
                 .returns(() => of(false));

frontend/app/shared/state/assets.state.ts

@@ -402,7 +402,7 @@ export abstract class AssetsStateBase extends State<Snapshot> {
 }
 
 function isReferrerError(error?: ErrorDto) {
-    return error?.statusCode === 400 && (!error?.details || error?.details.length === 0);
+    return error?.errorCode === 'OBJECT_REFERENCED';
 }
 
 function updateTags(snapshot: Snapshot, newAsset?: AssetDto, oldAsset?: AssetDto) {

frontend/app/shared/state/contents.state.ts

@@ -396,7 +396,7 @@ export abstract class ContentsStateBase extends State<Snapshot> {
 }
 
 function isReferrerError(error?: ErrorDto) {
-    return error?.statusCode === 400 && (!error?.details || error?.details.length === 0);
+    return error?.errorCode === 'OBJECT_REFERENCED';
 }
 
 @Injectable()