diff --git a/src/Squidex/Areas/Api/Controllers/Schemas/Models/Converters/FieldPropertiesDtoFactory.cs b/src/Squidex/Areas/Api/Controllers/Schemas/Models/Converters/FieldPropertiesDtoFactory.cs
index 9909d8435..60cff4b5f 100644
--- a/src/Squidex/Areas/Api/Controllers/Schemas/Models/Converters/FieldPropertiesDtoFactory.cs
+++ b/src/Squidex/Areas/Api/Controllers/Schemas/Models/Converters/FieldPropertiesDtoFactory.cs
@@ -5,7 +5,6 @@
 //  All rights reserved. Licensed under the MIT license.
 // ==========================================================================
 
-using System.Linq;
 using Squidex.Areas.Api.Controllers.Schemas.Models.Fields;
 using Squidex.Domain.Apps.Core.Schemas;
 using Squidex.Infrastructure.Reflection;
@@ -32,11 +31,7 @@ namespace Squidex.Areas.Api.Controllers.Schemas.Models.Converters
 
         public FieldPropertiesDto Visit(AssetsFieldProperties properties)
         {
-            var result = SimpleMapper.Map(properties, new AssetsFieldPropertiesDto());
-
-            result.AllowedExtensions = properties.AllowedExtensions?.ToArray();
-
-            return result;
+            return SimpleMapper.Map(properties, new AssetsFieldPropertiesDto());
         }
 
         public FieldPropertiesDto Visit(BooleanFieldProperties properties)
@@ -61,38 +56,22 @@ namespace Squidex.Areas.Api.Controllers.Schemas.Models.Converters
 
         public FieldPropertiesDto Visit(NumberFieldProperties properties)
         {
-            var result = SimpleMapper.Map(properties, new NumberFieldPropertiesDto());
-
-            result.AllowedValues = properties.AllowedValues?.ToArray();
-
-            return result;
+            return SimpleMapper.Map(properties, new NumberFieldPropertiesDto());
         }
 
         public FieldPropertiesDto Visit(ReferencesFieldProperties properties)
         {
-            var result = SimpleMapper.Map(properties, new ReferencesFieldPropertiesDto());
-
-            result.SchemaIds = properties.SchemaIds?.ToArray();
-
-            return result;
+            return SimpleMapper.Map(properties, new ReferencesFieldPropertiesDto());
         }
 
         public FieldPropertiesDto Visit(StringFieldProperties properties)
         {
-            var result = SimpleMapper.Map(properties, new StringFieldPropertiesDto());
-
-            result.AllowedValues = properties.AllowedValues?.ToArray();
-
-            return result;
+            return SimpleMapper.Map(properties, new StringFieldPropertiesDto());
         }
 
         public FieldPropertiesDto Visit(TagsFieldProperties properties)
         {
-            var result = SimpleMapper.Map(properties, new TagsFieldPropertiesDto());
-
-            result.AllowedValues = properties.AllowedValues?.ToArray();
-
-            return result;
+            return SimpleMapper.Map(properties, new TagsFieldPropertiesDto());
         }
 
         public FieldPropertiesDto Visit(UIFieldProperties properties)
diff --git a/src/Squidex/Areas/Api/Controllers/Schemas/Models/Fields/AssetsFieldPropertiesDto.cs b/src/Squidex/Areas/Api/Controllers/Schemas/Models/Fields/AssetsFieldPropertiesDto.cs
index 2dce75be1..1c95fe51a 100644
--- a/src/Squidex/Areas/Api/Controllers/Schemas/Models/Fields/AssetsFieldPropertiesDto.cs
+++ b/src/Squidex/Areas/Api/Controllers/Schemas/Models/Fields/AssetsFieldPropertiesDto.cs
@@ -5,8 +5,8 @@
 //  All rights reserved. Licensed under the MIT license.
 // ==========================================================================
 
+using System.Collections.ObjectModel;
 using Squidex.Domain.Apps.Core.Schemas;
-using Squidex.Infrastructure.Collections;
 using Squidex.Infrastructure.Reflection;
 
 namespace Squidex.Areas.Api.Controllers.Schemas.Models.Fields
@@ -76,7 +76,7 @@ namespace Squidex.Areas.Api.Controllers.Schemas.Models.Fields
         /// <summary>
         /// The allowed file extensions.
         /// </summary>
-        public string[] AllowedExtensions { get; set; }
+        public ReadOnlyCollection<string> AllowedExtensions { get; set; }
 
         /// <summary>
         /// True, if duplicate values are allowed.
@@ -87,11 +87,6 @@ namespace Squidex.Areas.Api.Controllers.Schemas.Models.Fields
         {
             var result = SimpleMapper.Map(this, new AssetsFieldProperties());
 
-            if (AllowedExtensions != null)
-            {
-                result.AllowedExtensions = ReadOnlyCollection.Create(AllowedExtensions);
-            }
-
             return result;
         }
     }
diff --git a/src/Squidex/Areas/Api/Controllers/Schemas/Models/Fields/JsonFieldPropertiesDto.cs b/src/Squidex/Areas/Api/Controllers/Schemas/Models/Fields/JsonFieldPropertiesDto.cs
index 2919d1370..8376073ef 100644
--- a/src/Squidex/Areas/Api/Controllers/Schemas/Models/Fields/JsonFieldPropertiesDto.cs
+++ b/src/Squidex/Areas/Api/Controllers/Schemas/Models/Fields/JsonFieldPropertiesDto.cs
@@ -14,7 +14,9 @@ namespace Squidex.Areas.Api.Controllers.Schemas.Models.Fields
     {
         public override FieldProperties ToProperties()
         {
-            return SimpleMapper.Map(this, new JsonFieldProperties());
+            var result = SimpleMapper.Map(this, new JsonFieldProperties());
+
+            return result;
         }
     }
 }
diff --git a/src/Squidex/Areas/Api/Controllers/Schemas/Models/Fields/NumberFieldPropertiesDto.cs b/src/Squidex/Areas/Api/Controllers/Schemas/Models/Fields/NumberFieldPropertiesDto.cs
index 13629fe7a..ddf1feefc 100644
--- a/src/Squidex/Areas/Api/Controllers/Schemas/Models/Fields/NumberFieldPropertiesDto.cs
+++ b/src/Squidex/Areas/Api/Controllers/Schemas/Models/Fields/NumberFieldPropertiesDto.cs
@@ -5,8 +5,8 @@
 //  All rights reserved. Licensed under the MIT license.
 // ==========================================================================
 
+using System.Collections.ObjectModel;
 using Squidex.Domain.Apps.Core.Schemas;
-using Squidex.Infrastructure.Collections;
 using Squidex.Infrastructure.Reflection;
 
 namespace Squidex.Areas.Api.Controllers.Schemas.Models.Fields
@@ -31,7 +31,7 @@ namespace Squidex.Areas.Api.Controllers.Schemas.Models.Fields
         /// <summary>
         /// The allowed values for the field value.
         /// </summary>
-        public double[] AllowedValues { get; set; }
+        public ReadOnlyCollection<double> AllowedValues { get; set; }
 
         /// <summary>
         /// Indicates if the field value must be unique. Ignored for nested fields and localized fields.
@@ -52,11 +52,6 @@ namespace Squidex.Areas.Api.Controllers.Schemas.Models.Fields
         {
             var result = SimpleMapper.Map(this, new NumberFieldProperties());
 
-            if (AllowedValues != null)
-            {
-                result.AllowedValues = ReadOnlyCollection.Create(AllowedValues);
-            }
-
             return result;
         }
     }
diff --git a/src/Squidex/Areas/Api/Controllers/Schemas/Models/Fields/ReferencesFieldPropertiesDto.cs b/src/Squidex/Areas/Api/Controllers/Schemas/Models/Fields/ReferencesFieldPropertiesDto.cs
index d85708d51..dfa873e01 100644
--- a/src/Squidex/Areas/Api/Controllers/Schemas/Models/Fields/ReferencesFieldPropertiesDto.cs
+++ b/src/Squidex/Areas/Api/Controllers/Schemas/Models/Fields/ReferencesFieldPropertiesDto.cs
@@ -6,6 +6,7 @@
 // ==========================================================================
 
 using System;
+using System.Collections.ObjectModel;
 using Squidex.Domain.Apps.Core.Schemas;
 using Squidex.Infrastructure.Collections;
 using Squidex.Infrastructure.Reflection;
@@ -42,17 +43,12 @@ namespace Squidex.Areas.Api.Controllers.Schemas.Models.Fields
         /// <summary>
         /// The id of the referenced schemas.
         /// </summary>
-        public Guid[] SchemaIds { get; set; }
+        public ReadOnlyCollection<Guid> SchemaIds { get; set; }
 
         public override FieldProperties ToProperties()
         {
             var result = SimpleMapper.Map(this, new ReferencesFieldProperties());
 
-            if (SchemaIds != null)
-            {
-                result.SchemaIds = ReadOnlyCollection.Create(SchemaIds);
-            }
-
             return result;
         }
     }
diff --git a/src/Squidex/Areas/Api/Controllers/Schemas/Models/Fields/StringFieldPropertiesDto.cs b/src/Squidex/Areas/Api/Controllers/Schemas/Models/Fields/StringFieldPropertiesDto.cs
index 59af7bd68..b5e21e146 100644
--- a/src/Squidex/Areas/Api/Controllers/Schemas/Models/Fields/StringFieldPropertiesDto.cs
+++ b/src/Squidex/Areas/Api/Controllers/Schemas/Models/Fields/StringFieldPropertiesDto.cs
@@ -5,8 +5,8 @@
 //  All rights reserved. Licensed under the MIT license.
 // ==========================================================================
 
+using System.Collections.ObjectModel;
 using Squidex.Domain.Apps.Core.Schemas;
-using Squidex.Infrastructure.Collections;
 using Squidex.Infrastructure.Reflection;
 
 namespace Squidex.Areas.Api.Controllers.Schemas.Models.Fields
@@ -41,7 +41,7 @@ namespace Squidex.Areas.Api.Controllers.Schemas.Models.Fields
         /// <summary>
         /// The allowed values for the field value.
         /// </summary>
-        public string[] AllowedValues { get; set; }
+        public ReadOnlyCollection<string> AllowedValues { get; set; }
 
         /// <summary>
         /// Indicates if the field value must be unique. Ignored for nested fields and localized fields.
@@ -62,11 +62,6 @@ namespace Squidex.Areas.Api.Controllers.Schemas.Models.Fields
         {
             var result = SimpleMapper.Map(this, new StringFieldProperties());
 
-            if (AllowedValues != null)
-            {
-                result.AllowedValues = ReadOnlyCollection.Create(AllowedValues);
-            }
-
             return result;
         }
     }
diff --git a/src/Squidex/Areas/Api/Controllers/Schemas/Models/Fields/TagsFieldPropertiesDto.cs b/src/Squidex/Areas/Api/Controllers/Schemas/Models/Fields/TagsFieldPropertiesDto.cs
index 449cdbf18..091832109 100644
--- a/src/Squidex/Areas/Api/Controllers/Schemas/Models/Fields/TagsFieldPropertiesDto.cs
+++ b/src/Squidex/Areas/Api/Controllers/Schemas/Models/Fields/TagsFieldPropertiesDto.cs
@@ -5,8 +5,8 @@
 //  All rights reserved. Licensed under the MIT license.
 // ==========================================================================
 
+using System.Collections.ObjectModel;
 using Squidex.Domain.Apps.Core.Schemas;
-using Squidex.Infrastructure.Collections;
 using Squidex.Infrastructure.Reflection;
 
 namespace Squidex.Areas.Api.Controllers.Schemas.Models.Fields
@@ -26,7 +26,7 @@ namespace Squidex.Areas.Api.Controllers.Schemas.Models.Fields
         /// <summary>
         /// The allowed values for the field value.
         /// </summary>
-        public string[] AllowedValues { get; set; }
+        public ReadOnlyCollection<string> AllowedValues { get; set; }
 
         /// <summary>
         /// The editor that is used to manage this field.
@@ -37,11 +37,6 @@ namespace Squidex.Areas.Api.Controllers.Schemas.Models.Fields
         {
             var result = SimpleMapper.Map(this, new TagsFieldProperties());
 
-            if (AllowedValues != null)
-            {
-                result.AllowedValues = ReadOnlyCollection.Create(AllowedValues);
-            }
-
             return result;
         }
     }
diff --git a/src/Squidex/Areas/Api/Controllers/Schemas/Models/Fields/UIFieldPropertiesDto.cs b/src/Squidex/Areas/Api/Controllers/Schemas/Models/Fields/UIFieldPropertiesDto.cs
index 866aa9a58..de59e2f25 100644
--- a/src/Squidex/Areas/Api/Controllers/Schemas/Models/Fields/UIFieldPropertiesDto.cs
+++ b/src/Squidex/Areas/Api/Controllers/Schemas/Models/Fields/UIFieldPropertiesDto.cs
@@ -19,7 +19,9 @@ namespace Squidex.Areas.Api.Controllers.Schemas.Models.Fields
 
         public override FieldProperties ToProperties()
         {
-            return SimpleMapper.Map(this, new UIFieldProperties());
+            var result = SimpleMapper.Map(this, new UIFieldProperties());
+
+            return result;
         }
     }
 }