diff --git a/src/Squidex.Domain.Apps.Core.Model/Apps/AppClient.cs b/src/Squidex.Domain.Apps.Core.Model/Apps/AppClient.cs
index 403dff845..9f6f0ed73 100644
--- a/src/Squidex.Domain.Apps.Core.Model/Apps/AppClient.cs
+++ b/src/Squidex.Domain.Apps.Core.Model/Apps/AppClient.cs
@@ -6,6 +6,7 @@
 //  All rights reserved.
 // ==========================================================================
 
+using System.Diagnostics.Contracts;
 using Squidex.Infrastructure;
 
 namespace Squidex.Domain.Apps.Core.Apps
@@ -42,6 +43,7 @@ namespace Squidex.Domain.Apps.Core.Apps
             this.permission = permission;
         }
 
+        [Pure]
         public AppClient Update(AppClientPermission newPermission)
         {
             Guard.Enum(newPermission, nameof(newPermission));
@@ -49,6 +51,7 @@ namespace Squidex.Domain.Apps.Core.Apps
             return new AppClient(name, secret, newPermission);
         }
 
+        [Pure]
         public AppClient Rename(string newName)
         {
             Guard.NotNullOrEmpty(newName, nameof(newName));
diff --git a/src/Squidex.Domain.Apps.Core.Model/Apps/AppClients.cs b/src/Squidex.Domain.Apps.Core.Model/Apps/AppClients.cs
index e1ee6f933..bd606ea0d 100644
--- a/src/Squidex.Domain.Apps.Core.Model/Apps/AppClients.cs
+++ b/src/Squidex.Domain.Apps.Core.Model/Apps/AppClients.cs
@@ -7,6 +7,7 @@
 // ==========================================================================
 
 using System.Collections.Immutable;
+using System.Diagnostics.Contracts;
 using Squidex.Infrastructure;
 
 namespace Squidex.Domain.Apps.Core.Apps
@@ -25,6 +26,7 @@ namespace Squidex.Domain.Apps.Core.Apps
         {
         }
 
+        [Pure]
         public AppClients Add(string id, AppClient client)
         {
             Guard.NotNullOrEmpty(id, nameof(id));
@@ -33,6 +35,7 @@ namespace Squidex.Domain.Apps.Core.Apps
             return new AppClients(Inner.Add(id, client));
         }
 
+        [Pure]
         public AppClients Add(string id, string secret)
         {
             Guard.NotNullOrEmpty(id, nameof(id));
@@ -40,6 +43,7 @@ namespace Squidex.Domain.Apps.Core.Apps
             return new AppClients(Inner.Add(id, new AppClient(id, secret, AppClientPermission.Editor)));
         }
 
+        [Pure]
         public AppClients Revoke(string id)
         {
             Guard.NotNullOrEmpty(id, nameof(id));
@@ -47,6 +51,7 @@ namespace Squidex.Domain.Apps.Core.Apps
             return new AppClients(Inner.Remove(id));
         }
 
+        [Pure]
         public AppClients Rename(string id, string newName)
         {
             Guard.NotNullOrEmpty(id, nameof(id));
@@ -59,6 +64,7 @@ namespace Squidex.Domain.Apps.Core.Apps
             return new AppClients(Inner.SetItem(id, client.Rename(newName)));
         }
 
+        [Pure]
         public AppClients Update(string id, AppClientPermission permission)
         {
             Guard.NotNullOrEmpty(id, nameof(id));
diff --git a/src/Squidex.Domain.Apps.Core.Model/Apps/AppContributors.cs b/src/Squidex.Domain.Apps.Core.Model/Apps/AppContributors.cs
index b9639881b..ffdd82c3f 100644
--- a/src/Squidex.Domain.Apps.Core.Model/Apps/AppContributors.cs
+++ b/src/Squidex.Domain.Apps.Core.Model/Apps/AppContributors.cs
@@ -7,6 +7,7 @@
 // ==========================================================================
 
 using System.Collections.Immutable;
+using System.Diagnostics.Contracts;
 using Squidex.Infrastructure;
 
 namespace Squidex.Domain.Apps.Core.Apps
@@ -25,6 +26,7 @@ namespace Squidex.Domain.Apps.Core.Apps
         {
         }
 
+        [Pure]
         public AppContributors Assign(string contributorId, AppContributorPermission permission)
         {
             Guard.NotNullOrEmpty(contributorId, nameof(contributorId));
@@ -33,6 +35,7 @@ namespace Squidex.Domain.Apps.Core.Apps
             return new AppContributors(Inner.SetItem(contributorId, permission));
         }
 
+        [Pure]
         public AppContributors Remove(string contributorId)
         {
             Guard.NotNullOrEmpty(contributorId, nameof(contributorId));
diff --git a/src/Squidex.Domain.Apps.Core.Model/Apps/LanguagesConfig.cs b/src/Squidex.Domain.Apps.Core.Model/Apps/LanguagesConfig.cs
index f5c262640..aa3a29666 100644
--- a/src/Squidex.Domain.Apps.Core.Model/Apps/LanguagesConfig.cs
+++ b/src/Squidex.Domain.Apps.Core.Model/Apps/LanguagesConfig.cs
@@ -10,6 +10,7 @@ using System;
 using System.Collections;
 using System.Collections.Generic;
 using System.Collections.Immutable;
+using System.Diagnostics.Contracts;
 using System.Linq;
 using Squidex.Infrastructure;
 
@@ -88,6 +89,7 @@ namespace Squidex.Domain.Apps.Core.Apps
             return Build(languages?.Select(x => new LanguageConfig(x)).ToList());
         }
 
+        [Pure]
         public LanguagesConfig MakeMaster(Language language)
         {
             Guard.NotNull(language, nameof(language));
@@ -95,6 +97,7 @@ namespace Squidex.Domain.Apps.Core.Apps
             return new LanguagesConfig(languages, languages[language]);
         }
 
+        [Pure]
         public LanguagesConfig Set(LanguageConfig config)
         {
             Guard.NotNull(config, nameof(config));
@@ -102,6 +105,7 @@ namespace Squidex.Domain.Apps.Core.Apps
             return new LanguagesConfig(languages.SetItem(config.Language, config), Master?.Language == config.Language ? config : Master);
         }
 
+        [Pure]
         public LanguagesConfig Remove(Language language)
         {
             Guard.NotNull(language, nameof(language));
diff --git a/src/Squidex.Domain.Apps.Core.Model/Rules/Rule.cs b/src/Squidex.Domain.Apps.Core.Model/Rules/Rule.cs
index 1e7a900b7..7bec58f87 100644
--- a/src/Squidex.Domain.Apps.Core.Model/Rules/Rule.cs
+++ b/src/Squidex.Domain.Apps.Core.Model/Rules/Rule.cs
@@ -7,6 +7,7 @@
 // ==========================================================================
 
 using System;
+using System.Diagnostics.Contracts;
 using Squidex.Infrastructure;
 
 namespace Squidex.Domain.Apps.Core.Rules
@@ -41,6 +42,7 @@ namespace Squidex.Domain.Apps.Core.Rules
             this.action = action;
         }
 
+        [Pure]
         public Rule Enable()
         {
             return Clone(clone =>
@@ -49,6 +51,7 @@ namespace Squidex.Domain.Apps.Core.Rules
             });
         }
 
+        [Pure]
         public Rule Disable()
         {
             return Clone(clone =>
@@ -57,6 +60,7 @@ namespace Squidex.Domain.Apps.Core.Rules
             });
         }
 
+        [Pure]
         public Rule Update(RuleTrigger newTrigger)
         {
             Guard.NotNull(newTrigger, nameof(newTrigger));
@@ -72,6 +76,7 @@ namespace Squidex.Domain.Apps.Core.Rules
             });
         }
 
+        [Pure]
         public Rule Update(RuleAction newAction)
         {
             Guard.NotNull(newAction, nameof(newAction));
diff --git a/src/Squidex.Domain.Apps.Core.Model/Schemas/AssetsFieldProperties.cs b/src/Squidex.Domain.Apps.Core.Model/Schemas/AssetsFieldProperties.cs
index f969b6603..c4de1e7f1 100644
--- a/src/Squidex.Domain.Apps.Core.Model/Schemas/AssetsFieldProperties.cs
+++ b/src/Squidex.Domain.Apps.Core.Model/Schemas/AssetsFieldProperties.cs
@@ -48,5 +48,10 @@ namespace Squidex.Domain.Apps.Core.Schemas
         {
             return visitor.Visit(this);
         }
+
+        public override Field CreateField(long id, string name, Partitioning partitioning)
+        {
+            return new AssetsField(id, name, partitioning, this);
+        }
     }
 }
diff --git a/src/Squidex.Domain.Apps.Core.Model/Schemas/BooleanFieldProperties.cs b/src/Squidex.Domain.Apps.Core.Model/Schemas/BooleanFieldProperties.cs
index cbd54521b..c6817f309 100644
--- a/src/Squidex.Domain.Apps.Core.Model/Schemas/BooleanFieldProperties.cs
+++ b/src/Squidex.Domain.Apps.Core.Model/Schemas/BooleanFieldProperties.cs
@@ -48,5 +48,10 @@ namespace Squidex.Domain.Apps.Core.Schemas
         {
             return visitor.Visit(this);
         }
+
+        public override Field CreateField(long id, string name, Partitioning partitioning)
+        {
+            return new BooleanField(id, name, partitioning, this);
+        }
     }
 }
diff --git a/src/Squidex.Domain.Apps.Core.Model/Schemas/DateTimeFieldProperties.cs b/src/Squidex.Domain.Apps.Core.Model/Schemas/DateTimeFieldProperties.cs
index 982de7e40..382fc8430 100644
--- a/src/Squidex.Domain.Apps.Core.Model/Schemas/DateTimeFieldProperties.cs
+++ b/src/Squidex.Domain.Apps.Core.Model/Schemas/DateTimeFieldProperties.cs
@@ -94,5 +94,10 @@ namespace Squidex.Domain.Apps.Core.Schemas
         {
             return visitor.Visit(this);
         }
+
+        public override Field CreateField(long id, string name, Partitioning partitioning)
+        {
+            return new DateTimeField(id, name, partitioning, this);
+        }
     }
 }
diff --git a/src/Squidex.Domain.Apps.Core.Model/Schemas/FieldProperties.cs b/src/Squidex.Domain.Apps.Core.Model/Schemas/FieldProperties.cs
index 315dfc925..aa530df70 100644
--- a/src/Squidex.Domain.Apps.Core.Model/Schemas/FieldProperties.cs
+++ b/src/Squidex.Domain.Apps.Core.Model/Schemas/FieldProperties.cs
@@ -57,5 +57,7 @@ namespace Squidex.Domain.Apps.Core.Schemas
         }
 
         public abstract T Accept<T>(IFieldPropertiesVisitor<T> visitor);
+
+        public abstract Field CreateField(long id, string name, Partitioning partitioning);
     }
 }
\ No newline at end of file
diff --git a/src/Squidex.Domain.Apps.Core.Model/Schemas/FieldRegistry.cs b/src/Squidex.Domain.Apps.Core.Model/Schemas/FieldRegistry.cs
index 710581ef1..5c6cecb70 100644
--- a/src/Squidex.Domain.Apps.Core.Model/Schemas/FieldRegistry.cs
+++ b/src/Squidex.Domain.Apps.Core.Model/Schemas/FieldRegistry.cs
@@ -17,29 +17,7 @@ namespace Squidex.Domain.Apps.Core.Schemas
         private delegate Field FactoryFunction(long id, string name, Partitioning partitioning, FieldProperties properties);
 
         private readonly TypeNameRegistry typeNameRegistry;
-        private readonly Dictionary<Type, Registered> fieldsByPropertyType = new Dictionary<Type, Registered>();
-
-        private sealed class Registered
-        {
-            private readonly FactoryFunction fieldFactory;
-            private readonly Type propertiesType;
-
-            public Type PropertiesType
-            {
-                get { return propertiesType; }
-            }
-
-            public Registered(FactoryFunction fieldFactory, Type propertiesType)
-            {
-                this.fieldFactory = fieldFactory;
-                this.propertiesType = propertiesType;
-            }
-
-            public Field CreateField(long id, string name, Partitioning partitioning, FieldProperties properties)
-            {
-                return fieldFactory(id, name, partitioning, properties);
-            }
-        }
+        private readonly Dictionary<Type, FactoryFunction> fieldsByPropertyType = new Dictionary<Type, FactoryFunction>();
 
         public FieldRegistry(TypeNameRegistry typeNameRegistry)
         {
@@ -47,69 +25,39 @@ namespace Squidex.Domain.Apps.Core.Schemas
 
             this.typeNameRegistry = typeNameRegistry;
 
-            Add<BooleanFieldProperties>(
-                (id, name, partitioning, properties) =>
-                    new BooleanField(id, name, partitioning, (BooleanFieldProperties)properties));
-
-            Add<NumberFieldProperties>(
-                (id, name, partitioning, properties) =>
-                    new NumberField(id, name, partitioning, (NumberFieldProperties)properties));
-
-            Add<StringFieldProperties>(
-                (id, name, partitioning, properties) =>
-                    new StringField(id, name, partitioning, (StringFieldProperties)properties));
-
-            Add<JsonFieldProperties>(
-                (id, name, partitioning, properties) =>
-                    new JsonField(id, name, partitioning, (JsonFieldProperties)properties));
-
-            Add<AssetsFieldProperties>(
-                (id, name, partitioning, properties) =>
-                    new AssetsField(id, name, partitioning, (AssetsFieldProperties)properties));
-
-            Add<GeolocationFieldProperties>(
-                (id, name, partitioning, properties) =>
-                    new GeolocationField(id, name, partitioning, (GeolocationFieldProperties)properties));
-
-            Add<ReferencesFieldProperties>(
-                (id, name, partitioning, properties) =>
-                    new ReferencesField(id, name, partitioning, (ReferencesFieldProperties)properties));
-
-            Add<DateTimeFieldProperties>(
-                (id, name, partitioning, properties) =>
-                    new DateTimeField(id, name, partitioning, (DateTimeFieldProperties)properties));
-
-            Add<TagsFieldProperties>(
-                (id, name, partitioning, properties) =>
-                    new TagsField(id, name, partitioning, (TagsFieldProperties)properties));
+            RegisterField<AssetsFieldProperties>();
+            RegisterField<BooleanFieldProperties>();
+            RegisterField<DateTimeFieldProperties>();
+            RegisterField<GeolocationFieldProperties>();
+            RegisterField<JsonFieldProperties>();
+            RegisterField<NumberFieldProperties>();
+            RegisterField<ReferencesFieldProperties>();
+            RegisterField<StringFieldProperties>();
+            RegisterField<TagsFieldProperties>();
 
             typeNameRegistry.MapObsolete(typeof(ReferencesFieldProperties), "DateTime");
             typeNameRegistry.MapObsolete(typeof(DateTimeFieldProperties), "References");
         }
 
-        private void Add<TFieldProperties>(FactoryFunction fieldFactory)
+        private void RegisterField<T>()
         {
-            Guard.NotNull(fieldFactory, nameof(fieldFactory));
-
-            typeNameRegistry.Map(typeof(TFieldProperties));
-
-            var registered = new Registered(fieldFactory, typeof(TFieldProperties));
+            typeNameRegistry.Map(typeof(T));
 
-            fieldsByPropertyType[registered.PropertiesType] = registered;
+            fieldsByPropertyType[typeof(T)] = (id, name, partitioning, properties) => properties.CreateField(id, name, partitioning);
         }
 
         public Field CreateField(long id, string name, Partitioning partitioning, FieldProperties properties)
         {
             Guard.NotNull(properties, nameof(properties));
 
-            var registered = fieldsByPropertyType.GetOrDefault(properties.GetType());
+            var factory = fieldsByPropertyType.GetOrDefault(properties.GetType());
 
-            if (registered == null)
+            if (factory == null)
             {
                 throw new InvalidOperationException($"The field property '{properties.GetType()}' is not supported.");
             }
 
-            return registered.CreateField(id, name, partitioning, properties);
+            return factory(id, name, partitioning, properties);
         }
     }
 }
diff --git a/src/Squidex.Domain.Apps.Core.Model/Schemas/GeolocationFieldProperties.cs b/src/Squidex.Domain.Apps.Core.Model/Schemas/GeolocationFieldProperties.cs
index e82e6ab89..e01fddcb4 100644
--- a/src/Squidex.Domain.Apps.Core.Model/Schemas/GeolocationFieldProperties.cs
+++ b/src/Squidex.Domain.Apps.Core.Model/Schemas/GeolocationFieldProperties.cs
@@ -33,5 +33,10 @@ namespace Squidex.Domain.Apps.Core.Schemas
         {
             return visitor.Visit(this);
         }
+
+        public override Field CreateField(long id, string name, Partitioning partitioning)
+        {
+            return new GeolocationField(id, name, partitioning, this);
+        }
     }
 }
diff --git a/src/Squidex.Domain.Apps.Core.Model/Schemas/JsonFieldProperties.cs b/src/Squidex.Domain.Apps.Core.Model/Schemas/JsonFieldProperties.cs
index c432be09a..5c4ffd918 100644
--- a/src/Squidex.Domain.Apps.Core.Model/Schemas/JsonFieldProperties.cs
+++ b/src/Squidex.Domain.Apps.Core.Model/Schemas/JsonFieldProperties.cs
@@ -17,5 +17,10 @@ namespace Squidex.Domain.Apps.Core.Schemas
         {
             return visitor.Visit(this);
         }
+
+        public override Field CreateField(long id, string name, Partitioning partitioning)
+        {
+            return new JsonField(id, name, partitioning, this);
+        }
     }
 }
diff --git a/src/Squidex.Domain.Apps.Core.Model/Schemas/NumberFieldProperties.cs b/src/Squidex.Domain.Apps.Core.Model/Schemas/NumberFieldProperties.cs
index 2fe90fd73..f7d6af843 100644
--- a/src/Squidex.Domain.Apps.Core.Model/Schemas/NumberFieldProperties.cs
+++ b/src/Squidex.Domain.Apps.Core.Model/Schemas/NumberFieldProperties.cs
@@ -94,5 +94,10 @@ namespace Squidex.Domain.Apps.Core.Schemas
         {
             return visitor.Visit(this);
         }
+
+        public override Field CreateField(long id, string name, Partitioning partitioning)
+        {
+            return new NumberField(id, name, partitioning, this);
+        }
     }
 }
diff --git a/src/Squidex.Domain.Apps.Core.Model/Schemas/ReferencesFieldProperties.cs b/src/Squidex.Domain.Apps.Core.Model/Schemas/ReferencesFieldProperties.cs
index bfc5119a0..3faa12a26 100644
--- a/src/Squidex.Domain.Apps.Core.Model/Schemas/ReferencesFieldProperties.cs
+++ b/src/Squidex.Domain.Apps.Core.Model/Schemas/ReferencesFieldProperties.cs
@@ -64,5 +64,10 @@ namespace Squidex.Domain.Apps.Core.Schemas
         {
             return visitor.Visit(this);
         }
+
+        public override Field CreateField(long id, string name, Partitioning partitioning)
+        {
+            return new ReferencesField(id, name, partitioning, this);
+        }
     }
 }
diff --git a/src/Squidex.Domain.Apps.Core.Model/Schemas/StringFieldProperties.cs b/src/Squidex.Domain.Apps.Core.Model/Schemas/StringFieldProperties.cs
index 849ac97a8..80c2d6cbc 100644
--- a/src/Squidex.Domain.Apps.Core.Model/Schemas/StringFieldProperties.cs
+++ b/src/Squidex.Domain.Apps.Core.Model/Schemas/StringFieldProperties.cs
@@ -124,5 +124,10 @@ namespace Squidex.Domain.Apps.Core.Schemas
         {
             return visitor.Visit(this);
         }
+
+        public override Field CreateField(long id, string name, Partitioning partitioning)
+        {
+            return new StringField(id, name, partitioning, this);
+        }
     }
 }
diff --git a/src/Squidex.Domain.Apps.Core.Model/Schemas/TagsFieldProperties.cs b/src/Squidex.Domain.Apps.Core.Model/Schemas/TagsFieldProperties.cs
index 99b48b2d3..579c65ca5 100644
--- a/src/Squidex.Domain.Apps.Core.Model/Schemas/TagsFieldProperties.cs
+++ b/src/Squidex.Domain.Apps.Core.Model/Schemas/TagsFieldProperties.cs
@@ -48,5 +48,10 @@ namespace Squidex.Domain.Apps.Core.Schemas
         {
             return visitor.Visit(this);
         }
+
+        public override Field CreateField(long id, string name, Partitioning partitioning)
+        {
+            return new TagsField(id, name, partitioning, this);
+        }
     }
 }
diff --git a/src/Squidex.Infrastructure.MongoDb/MongoDb/BsonJsonConvention.cs b/src/Squidex.Infrastructure.MongoDb/MongoDb/BsonJsonConvention.cs
index 62f163f47..b9964135e 100644
--- a/src/Squidex.Infrastructure.MongoDb/MongoDb/BsonJsonConvention.cs
+++ b/src/Squidex.Infrastructure.MongoDb/MongoDb/BsonJsonConvention.cs
@@ -27,7 +27,7 @@ namespace Squidex.Infrastructure.MongoDb
 
                 if (attributes.OfType<BsonJsonAttribute>().Any())
                 {
-                    var bsonSerializerType = typeof(JsonBsonSerializer<>).MakeGenericType(memberMap.MemberType);
+                    var bsonSerializerType = typeof(BsonJsonSerializer<>).MakeGenericType(memberMap.MemberType);
                     var bsonSerializer = Activator.CreateInstance(bsonSerializerType, serializer);
 
                     memberMap.SetSerializer((IBsonSerializer)bsonSerializer);
diff --git a/src/Squidex.Infrastructure.MongoDb/MongoDb/JsonBsonConverter.cs b/src/Squidex.Infrastructure.MongoDb/MongoDb/BsonJsonConverter.cs
similarity index 98%
rename from src/Squidex.Infrastructure.MongoDb/MongoDb/JsonBsonConverter.cs
rename to src/Squidex.Infrastructure.MongoDb/MongoDb/BsonJsonConverter.cs
index 4ff5b988c..20ec6e1ee 100644
--- a/src/Squidex.Infrastructure.MongoDb/MongoDb/JsonBsonConverter.cs
+++ b/src/Squidex.Infrastructure.MongoDb/MongoDb/BsonJsonConverter.cs
@@ -1,5 +1,5 @@
 // ==========================================================================
-//  JsonBsonConverter.cs
+//  BsonJsonConverter.cs
 //  Squidex Headless CMS
 // ==========================================================================
 //  Copyright (c) Squidex Group
@@ -12,7 +12,7 @@ using Newtonsoft.Json.Linq;
 
 namespace Squidex.Infrastructure.MongoDb
 {
-    public static class JsonBsonConverter
+    public static class BsonJsonConverter
     {
         public static BsonDocument ToBson(this JObject source)
         {
diff --git a/src/Squidex.Infrastructure.MongoDb/MongoDb/BsonJsonReader.cs b/src/Squidex.Infrastructure.MongoDb/MongoDb/BsonJsonReader.cs
index ef0e6621e..bd7003da0 100644
--- a/src/Squidex.Infrastructure.MongoDb/MongoDb/BsonJsonReader.cs
+++ b/src/Squidex.Infrastructure.MongoDb/MongoDb/BsonJsonReader.cs
@@ -27,7 +27,9 @@ namespace Squidex.Infrastructure.MongoDb
 
         public override bool Read()
         {
-            if (bsonReader.State == BsonReaderState.Type)
+            if (bsonReader.State == BsonReaderState.Initial ||
+                bsonReader.State == BsonReaderState.ScopeDocument ||
+                bsonReader.State == BsonReaderState.Type)
             {
                 bsonReader.ReadBsonType();
             }
@@ -60,9 +62,11 @@ namespace Squidex.Infrastructure.MongoDb
                         break;
                     case BsonType.Undefined:
                         SetToken(NewtonsoftJsonToken.Undefined);
+                        bsonReader.ReadUndefined();
                         break;
                     case BsonType.Null:
                         SetToken(NewtonsoftJsonToken.Null);
+                        bsonReader.ReadNull();
                         break;
                     case BsonType.String:
                         SetToken(NewtonsoftJsonToken.String, bsonReader.ReadString());
@@ -93,6 +97,11 @@ namespace Squidex.Infrastructure.MongoDb
                 }
             }
 
+            if (bsonReader.State == BsonReaderState.Initial)
+            {
+                return true;
+            }
+
             return !bsonReader.IsAtEndOfFile();
         }
     }
diff --git a/src/Squidex.Infrastructure.MongoDb/MongoDb/JsonBsonSerializer.cs b/src/Squidex.Infrastructure.MongoDb/MongoDb/BsonJsonSerializer.cs
similarity index 90%
rename from src/Squidex.Infrastructure.MongoDb/MongoDb/JsonBsonSerializer.cs
rename to src/Squidex.Infrastructure.MongoDb/MongoDb/BsonJsonSerializer.cs
index c6a77df80..f19987464 100644
--- a/src/Squidex.Infrastructure.MongoDb/MongoDb/JsonBsonSerializer.cs
+++ b/src/Squidex.Infrastructure.MongoDb/MongoDb/BsonJsonSerializer.cs
@@ -14,11 +14,11 @@ using Newtonsoft.Json.Linq;
 
 namespace Squidex.Infrastructure.MongoDb
 {
-    public class JsonBsonSerializer<T> : ClassSerializerBase<T> where T : class
+    public class BsonJsonSerializer<T> : ClassSerializerBase<T> where T : class
     {
         private readonly JsonSerializer serializer;
 
-        public JsonBsonSerializer(JsonSerializer serializer)
+        public BsonJsonSerializer(JsonSerializer serializer)
         {
             Guard.NotNull(serializer, nameof(serializer));
 
diff --git a/src/Squidex.Infrastructure.MongoDb/States/MongoStateStore.cs b/src/Squidex.Infrastructure.MongoDb/States/MongoStateStore.cs
index c494e4054..d65bc6416 100644
--- a/src/Squidex.Infrastructure.MongoDb/States/MongoStateStore.cs
+++ b/src/Squidex.Infrastructure.MongoDb/States/MongoStateStore.cs
@@ -62,12 +62,13 @@ namespace Squidex.Infrastructure.States
 
             try
             {
-                await collection.InsertOneAsync(
-                    /*Builders<MongoState<T>>.Filter.And(
-                        Builders<MongoState<T>>.Filter.Eq(nameof(MongoState<T>.Id), key),
-                        Builders<MongoState<T>>.Filter.Eq(nameof(MongoState<T>.Etag), oldEtag)
-                    ),*/
-                    new MongoState<T> { Id = key, Etag = newEtag, Doc = value });
+                await collection.UpdateOneAsync(
+                    Builders<MongoState<T>>.Filter.And(
+                        Builders<MongoState<T>>.Filter.Eq(x => x.Id, key),
+                        Builders<MongoState<T>>.Filter.Eq(x => x.Etag, oldEtag)
+                    ),
+                    Builders<MongoState<T>>.Update.Set(x => x.Doc, value),
+                    Upsert);
             }
             catch (MongoWriteException ex)
             {
diff --git a/tests/Benchmarks/IBenchmark.cs b/tests/Benchmarks/Benchmark.cs
similarity index 54%
rename from tests/Benchmarks/IBenchmark.cs
rename to tests/Benchmarks/Benchmark.cs
index 779531450..2bf549ceb 100644
--- a/tests/Benchmarks/IBenchmark.cs
+++ b/tests/Benchmarks/Benchmark.cs
@@ -8,12 +8,24 @@
 
 namespace Benchmarks
 {
-    public interface IBenchmark
+    public abstract class Benchmark
     {
-        void RunInitialize();
+        public virtual void Initialize()
+        {
+        }
 
-        long Run();
+        public virtual void RunInitialize()
+        {
+        }
 
-        void RunCleanup();
+        public virtual void RunCleanup()
+        {
+        }
+
+        public virtual void Cleanup()
+        {
+        }
+
+        public abstract long Run();
     }
 }
diff --git a/tests/Benchmarks/Program.cs b/tests/Benchmarks/Program.cs
index 2e408b32e..c04991e0f 100644
--- a/tests/Benchmarks/Program.cs
+++ b/tests/Benchmarks/Program.cs
@@ -16,7 +16,7 @@ namespace Benchmarks
 {
     public static class Program
     {
-        private static readonly List<(string Name, IBenchmark Benchmark)> Benchmarks = new IBenchmark[]
+        private static readonly List<(string Name, Benchmark Benchmark)> Benchmarks = new Benchmark[]
         {
             new AppendToEventStore(),
             new AppendToEventStoreWithManyWriters(),
@@ -51,6 +51,8 @@ namespace Benchmarks
 
                     Console.WriteLine($"{selected.Name}: Initialized");
 
+                    selected.Benchmark.Initialize();
+
                     for (var run = 0; run < numRuns; run++)
                     {
                         try
@@ -82,6 +84,10 @@ namespace Benchmarks
                 {
                     Console.WriteLine($"Benchmark failed with '{e.Message}'");
                 }
+                finally
+                {
+                    selected.Benchmark.Cleanup();
+                }
             }
 
             Console.ReadLine();
diff --git a/tests/Benchmarks/Tests/AppendToEventStore.cs b/tests/Benchmarks/Tests/AppendToEventStore.cs
index 16cc26ea7..d33e20cde 100644
--- a/tests/Benchmarks/Tests/AppendToEventStore.cs
+++ b/tests/Benchmarks/Tests/AppendToEventStore.cs
@@ -13,19 +13,19 @@ using Squidex.Infrastructure.CQRS.Events;
 
 namespace Benchmarks.Tests
 {
-    public sealed class AppendToEventStore : IBenchmark
+    public sealed class AppendToEventStore : Benchmark
     {
         private IServiceProvider services;
         private IEventStore eventStore;
 
-        public void RunInitialize()
+        public override void RunInitialize()
         {
             services = Services.Create();
 
             eventStore = services.GetRequiredService<IEventStore>();
         }
 
-        public long Run()
+        public override long Run()
         {
             const long numCommits = 100;
             const long numStreams = 20;
@@ -45,7 +45,7 @@ namespace Benchmarks.Tests
             return numCommits * numStreams;
         }
 
-        public void RunCleanup()
+        public override void RunCleanup()
         {
             services.Cleanup();
         }
diff --git a/tests/Benchmarks/Tests/AppendToEventStoreWithManyWriters.cs b/tests/Benchmarks/Tests/AppendToEventStoreWithManyWriters.cs
index 307f52cd5..ede647b4f 100644
--- a/tests/Benchmarks/Tests/AppendToEventStoreWithManyWriters.cs
+++ b/tests/Benchmarks/Tests/AppendToEventStoreWithManyWriters.cs
@@ -14,19 +14,19 @@ using Squidex.Infrastructure.CQRS.Events;
 
 namespace Benchmarks.Tests
 {
-    public sealed class AppendToEventStoreWithManyWriters : IBenchmark
+    public sealed class AppendToEventStoreWithManyWriters : Benchmark
     {
         private IServiceProvider services;
         private IEventStore eventStore;
 
-        public void RunInitialize()
+        public override void RunInitialize()
         {
             services = Services.Create();
 
             eventStore = services.GetRequiredService<IEventStore>();
         }
 
-        public long Run()
+        public override long Run()
         {
             const long numCommits = 200;
             const long numStreams = 100;
@@ -44,7 +44,7 @@ namespace Benchmarks.Tests
             return numCommits * numStreams;
         }
 
-        public void RunCleanup()
+        public override void RunCleanup()
         {
             services.Cleanup();
         }
diff --git a/tests/Benchmarks/Tests/HandleEvents.cs b/tests/Benchmarks/Tests/HandleEvents.cs
index 121de4b25..a9c060ce3 100644
--- a/tests/Benchmarks/Tests/HandleEvents.cs
+++ b/tests/Benchmarks/Tests/HandleEvents.cs
@@ -15,7 +15,7 @@ using Squidex.Infrastructure.States;
 
 namespace Benchmarks.Tests
 {
-    public sealed class HandleEvents : IBenchmark
+    public sealed class HandleEvents : Benchmark
     {
         private const int NumEvents = 5000;
         private IServiceProvider services;
@@ -24,7 +24,7 @@ namespace Benchmarks.Tests
         private EventDataFormatter eventDataFormatter;
         private MyEventConsumer eventConsumer;
 
-        public void RunInitialize()
+        public override void RunInitialize()
         {
             services = Services.Create();
 
@@ -39,7 +39,7 @@ namespace Benchmarks.Tests
             eventConsumerActor.Activate(eventConsumer);
         }
 
-        public long Run()
+        public override long Run()
         {
             var streamName = Guid.NewGuid().ToString();
 
@@ -55,7 +55,7 @@ namespace Benchmarks.Tests
             return NumEvents;
         }
 
-        public void RunCleanup()
+        public override void RunCleanup()
         {
             services.Cleanup();
         }
diff --git a/tests/Benchmarks/Tests/HandleEventsWithManyWriters.cs b/tests/Benchmarks/Tests/HandleEventsWithManyWriters.cs
index 63d98da39..b76640717 100644
--- a/tests/Benchmarks/Tests/HandleEventsWithManyWriters.cs
+++ b/tests/Benchmarks/Tests/HandleEventsWithManyWriters.cs
@@ -16,7 +16,7 @@ using Squidex.Infrastructure.States;
 
 namespace Benchmarks.Tests
 {
-    public sealed class HandleEventsWithManyWriters : IBenchmark
+    public sealed class HandleEventsWithManyWriters : Benchmark
     {
         private const int NumCommits = 200;
         private const int NumStreams = 10;
@@ -26,7 +26,7 @@ namespace Benchmarks.Tests
         private EventDataFormatter eventDataFormatter;
         private MyEventConsumer eventConsumer;
 
-        public void RunInitialize()
+        public override void RunInitialize()
         {
             services = Services.Create();
 
@@ -41,7 +41,7 @@ namespace Benchmarks.Tests
             eventConsumerActor.Activate(eventConsumer);
         }
 
-        public long Run()
+        public override long Run()
         {
             Parallel.For(0, NumStreams, streamId =>
             {
@@ -62,7 +62,7 @@ namespace Benchmarks.Tests
             return NumStreams * NumCommits;
         }
 
-        public void RunCleanup()
+        public override void RunCleanup()
         {
             services.Cleanup();
         }
diff --git a/tests/Benchmarks/Tests/ReadSchemaState.cs b/tests/Benchmarks/Tests/ReadSchemaState.cs
index f0b63e25b..e12dcfa33 100644
--- a/tests/Benchmarks/Tests/ReadSchemaState.cs
+++ b/tests/Benchmarks/Tests/ReadSchemaState.cs
@@ -22,12 +22,12 @@ using Squidex.Infrastructure.States;
 
 namespace Benchmarks.Tests
 {
-    public class ReadSchemaState : IBenchmark
+    public class ReadSchemaState : Benchmark
     {
         private IServiceProvider services;
         private MyAppState grain;
 
-        public void RunInitialize()
+        public override void Initialize()
         {
             services = Services.Create();
 
@@ -84,7 +84,7 @@ namespace Benchmarks.Tests
             grain.WriteStateAsync().Wait();
         }
 
-        public long Run()
+        public override long Run()
         {
             for (var i = 0; i < 10; i++)
             {
@@ -94,7 +94,7 @@ namespace Benchmarks.Tests
             return 10;
         }
 
-        public void RunCleanup()
+        public override void Cleanup()
         {
             services.Cleanup();
         }
diff --git a/tests/Squidex.Infrastructure.Tests/MongoDb/BsonConverterTests.cs b/tests/Squidex.Infrastructure.Tests/MongoDb/BsonConverterTests.cs
index 51bbd15e3..28ebd4b73 100644
--- a/tests/Squidex.Infrastructure.Tests/MongoDb/BsonConverterTests.cs
+++ b/tests/Squidex.Infrastructure.Tests/MongoDb/BsonConverterTests.cs
@@ -7,7 +7,11 @@
 // ==========================================================================
 
 using System;
+using System.IO;
+using System.Linq;
 using FluentAssertions;
+using MongoDB.Bson.IO;
+using Newtonsoft.Json;
 using Newtonsoft.Json.Linq;
 using Xunit;
 
@@ -19,14 +23,30 @@ namespace Squidex.Infrastructure.MongoDb
     {
         public class TestObject
         {
-            public TimeSpan TimeSpan { get; set; }
+            public bool Bool { get; set; }
+
+            public byte Byte { get; set; }
+
+            public byte[] Bytes { get; set; }
+
+            public string String { get; set; }
+
+            public string[] Strings { get; set; }
+
+            public float Float32 { get; set; }
+
+            public double Float64 { get; set; }
+
+            public Uri Uri { get; set; }
 
             public Guid Guid { get; set; }
 
-            public DateTimeOffset DateTimeOffset { get; set; }
+            public TimeSpan TimeSpan { get; set; }
 
             public DateTime DateTime { get; set; }
 
+            public DateTimeOffset DateTimeOffset { get; set; }
+
             public Int64 Int64 { get; set; }
 
             public Int32 Int32 { get; set; }
@@ -39,25 +59,13 @@ namespace Squidex.Infrastructure.MongoDb
 
             public UInt16 UInt16 { get; set; }
 
-            public double Float64 { get; set; }
-
-            public float Float32 { get; set; }
+            public TestObject Nested { get; set; }
 
-            public bool Bool { get; set; }
-
-            public byte Byte { get; set; }
+            public TestObject[] NestedArray { get; set; }
 
-            public byte[] Bytes { get; set; }
-
-            public string String { get; set; }
-
-            public string[] Strings { get; set; }
-
-            public Uri Uri { get; set; }
-
-            public static TestObject CreateWithValues()
+            public static TestObject CreateWithValues(bool nested = true)
             {
-                return new TestObject
+                var result = new TestObject
                 {
                     Bool = true,
                     Byte = 0x2,
@@ -78,16 +86,48 @@ namespace Squidex.Infrastructure.MongoDb
                     UInt16 = 116,
                     Uri = new Uri("http://squidex.io")
                 };
+
+                if (nested)
+                {
+                    result.Nested = CreateWithValues(false);
+                    result.NestedArray = Enumerable.Repeat(0, 4).Select(x => CreateWithValues(false)).ToArray();
+                }
+
+                return result;
             }
         }
 
+        private readonly TestObject source = TestObject.CreateWithValues();
+        private readonly JsonSerializer serializer = JsonSerializer.CreateDefault();
+
         [Fact]
         public void Should_serialize_and_deserialize_to_bson_with_json()
         {
-            var source = TestObject.CreateWithValues();
             var target = JObject.FromObject(source).ToBson().ToJson().ToObject<TestObject>();
 
             target.ShouldBeEquivalentTo(source);
         }
+
+        [Fact]
+        public void Should_serialize_with_reader_and_writer()
+        {
+            var stream = new MemoryStream();
+
+            using (var writer = new BsonJsonWriter(new BsonBinaryWriter(stream)))
+            {
+                serializer.Serialize(writer, source);
+
+                writer.Flush();
+            }
+
+            stream.Position = 0;
+
+            using (var reader = new BsonJsonReader(new BsonBinaryReader(stream)))
+            {
+                var target = serializer.Deserialize<TestObject>(reader);
+
+                target.ShouldBeEquivalentTo(source);
+            }
+        }
     }
 }