diff --git a/src/Squidex.Domain.Apps.Core/Schemas/AssetsField.cs b/src/Squidex.Domain.Apps.Core/Schemas/AssetsField.cs
index 7cdee7fa4..ec4743d14 100644
--- a/src/Squidex.Domain.Apps.Core/Schemas/AssetsField.cs
+++ b/src/Squidex.Domain.Apps.Core/Schemas/AssetsField.cs
@@ -8,6 +8,7 @@
 
 using System;
 using System.Collections.Generic;
+using System.Collections.Immutable;
 using System.Linq;
 using Newtonsoft.Json.Linq;
 using Squidex.Domain.Apps.Core.Schemas.Validators;
@@ -16,7 +17,7 @@ namespace Squidex.Domain.Apps.Core.Schemas
 {
     public sealed class AssetsField : Field<AssetsFieldProperties>, IReferenceField
     {
-        private static readonly Guid[] EmptyIds = new Guid[0];
+        private static readonly ImmutableList<Guid> EmptyIds = ImmutableList<Guid>.Empty;
 
         public AssetsField(long id, string name, Partitioning partitioning)
             : this(id, name, partitioning, new AssetsFieldProperties())
@@ -30,22 +31,27 @@ namespace Squidex.Domain.Apps.Core.Schemas
 
         protected override IEnumerable<IValidator> CreateValidators()
         {
-            yield return new AssetsValidator(Properties.IsRequired, Properties.MinItems, Properties.MaxItems);
+            if (Properties.IsRequired || Properties.MinItems.HasValue || Properties.MaxItems.HasValue)
+            {
+                yield return new CollectionValidator<Guid>(Properties.IsRequired, Properties.MinItems, Properties.MaxItems);
+            }
+
+            yield return new AssetsValidator();
         }
 
         public IEnumerable<Guid> GetReferencedIds(JToken value)
         {
-            Guid[] assetIds;
+            IEnumerable<Guid> result = null;
             try
             {
-                assetIds = value?.ToObject<Guid[]>() ?? EmptyIds;
+                result = value?.ToObject<List<Guid>>();
             }
             catch
             {
-                assetIds = EmptyIds;
+                result = EmptyIds;
             }
 
-            return assetIds;
+            return result ?? EmptyIds;
         }
 
         public JToken RemoveDeletedReferences(JToken value, ISet<Guid> deletedReferencedIds)
@@ -63,7 +69,7 @@ namespace Squidex.Domain.Apps.Core.Schemas
 
         public override object ConvertValue(JToken value)
         {
-            return new AssetsValue(value.ToObject<Guid[]>());
+            return value.ToObject<List<Guid>>();
         }
 
         public override T Visit<T>(IFieldVisitor<T> visitor)
diff --git a/src/Squidex.Domain.Apps.Core/Schemas/AssetsValue.cs b/src/Squidex.Domain.Apps.Core/Schemas/AssetsValue.cs
deleted file mode 100644
index 492c74548..000000000
--- a/src/Squidex.Domain.Apps.Core/Schemas/AssetsValue.cs
+++ /dev/null
@@ -1,25 +0,0 @@
-// ==========================================================================
-//  AssetsValue.cs
-//  Squidex Headless CMS
-// ==========================================================================
-//  Copyright (c) Squidex Group
-//  All rights reserved.
-// ==========================================================================
-
-using System;
-using System.Collections.Generic;
-
-namespace Squidex.Domain.Apps.Core.Schemas
-{
-    public sealed class AssetsValue
-    {
-        private static readonly List<Guid> EmptyAssetIds = new List<Guid>();
-
-        public IReadOnlyList<Guid> AssetIds { get; }
-
-        public AssetsValue(IReadOnlyList<Guid> assetIds)
-        {
-            AssetIds = assetIds ?? EmptyAssetIds;
-        }
-    }
-}
diff --git a/src/Squidex.Domain.Apps.Core/Schemas/ReferencesField.cs b/src/Squidex.Domain.Apps.Core/Schemas/ReferencesField.cs
index b978c7273..6e108e0cb 100644
--- a/src/Squidex.Domain.Apps.Core/Schemas/ReferencesField.cs
+++ b/src/Squidex.Domain.Apps.Core/Schemas/ReferencesField.cs
@@ -8,6 +8,7 @@
 
 using System;
 using System.Collections.Generic;
+using System.Collections.Immutable;
 using System.Linq;
 using Newtonsoft.Json.Linq;
 using Squidex.Domain.Apps.Core.Schemas.Validators;
@@ -16,7 +17,7 @@ namespace Squidex.Domain.Apps.Core.Schemas
 {
     public sealed class ReferencesField : Field<ReferencesFieldProperties>, IReferenceField
     {
-        private static readonly Guid[] EmptyIds = new Guid[0];
+        private static readonly ImmutableList<Guid> EmptyIds = ImmutableList<Guid>.Empty;
 
         public ReferencesField(long id, string name, Partitioning partitioning)
             : this(id, name, partitioning, new ReferencesFieldProperties())
@@ -30,25 +31,30 @@ namespace Squidex.Domain.Apps.Core.Schemas
 
         protected override IEnumerable<IValidator> CreateValidators()
         {
+            if (Properties.IsRequired || Properties.MinItems.HasValue || Properties.MaxItems.HasValue)
+            {
+                yield return new CollectionValidator<Guid>(Properties.IsRequired, Properties.MinItems, Properties.MaxItems);
+            }
+
             if (Properties.SchemaId != Guid.Empty)
             {
-                yield return new ReferencesValidator(Properties.IsRequired, Properties.SchemaId, Properties.MinItems, Properties.MaxItems);
+                yield return new ReferencesValidator(Properties.SchemaId);
             }
         }
 
         public IEnumerable<Guid> GetReferencedIds(JToken value)
         {
-            Guid[] referenceIds;
+            IEnumerable<Guid> result = null;
             try
             {
-                referenceIds = value?.ToObject<Guid[]>() ?? EmptyIds;
+                result = value?.ToObject<List<Guid>>();
             }
             catch
             {
-                referenceIds = EmptyIds;
+                result = EmptyIds;
             }
 
-            return referenceIds.Union(new[] { Properties.SchemaId });
+            return (result ?? EmptyIds).Union(new[] { Properties.SchemaId });
         }
 
         public JToken RemoveDeletedReferences(JToken value, ISet<Guid> deletedReferencedIds)
@@ -71,7 +77,7 @@ namespace Squidex.Domain.Apps.Core.Schemas
 
         public override object ConvertValue(JToken value)
         {
-            return new ReferencesValue(value.ToObject<Guid[]>());
+            return value.ToObject<List<Guid>>();
         }
 
         public override T Visit<T>(IFieldVisitor<T> visitor)
diff --git a/src/Squidex.Domain.Apps.Core/Schemas/ReferencesValue.cs b/src/Squidex.Domain.Apps.Core/Schemas/ReferencesValue.cs
deleted file mode 100644
index de9b660c9..000000000
--- a/src/Squidex.Domain.Apps.Core/Schemas/ReferencesValue.cs
+++ /dev/null
@@ -1,25 +0,0 @@
-// ==========================================================================
-//  ReferencesValue.cs
-//  Squidex Headless CMS
-// ==========================================================================
-//  Copyright (c) Squidex Group
-//  All rights reserved.
-// ==========================================================================
-
-using System;
-using System.Collections.Generic;
-
-namespace Squidex.Domain.Apps.Core.Schemas
-{
-    public sealed class ReferencesValue
-    {
-        private static readonly List<Guid> EmptyReferencedIds = new List<Guid>();
-
-        public IReadOnlyList<Guid> ContentIds { get; }
-
-        public ReferencesValue(IReadOnlyList<Guid> assetIds)
-        {
-            ContentIds = assetIds ?? EmptyReferencedIds;
-        }
-    }
-}
diff --git a/src/Squidex.Domain.Apps.Core/Schemas/Validators/AssetsValidator.cs b/src/Squidex.Domain.Apps.Core/Schemas/Validators/AssetsValidator.cs
index 72eeecb9f..91c607f78 100644
--- a/src/Squidex.Domain.Apps.Core/Schemas/Validators/AssetsValidator.cs
+++ b/src/Squidex.Domain.Apps.Core/Schemas/Validators/AssetsValidator.cs
@@ -7,50 +7,23 @@
 // ==========================================================================
 
 using System;
+using System.Collections.Generic;
 using System.Threading.Tasks;
 
 namespace Squidex.Domain.Apps.Core.Schemas.Validators
 {
     public sealed class AssetsValidator : IValidator
     {
-        private readonly bool isRequired;
-        private readonly int? minItems;
-        private readonly int? maxItems;
-
-        public AssetsValidator(bool isRequired, int? minItems = null, int? maxItems = null)
-        {
-            this.isRequired = isRequired;
-            this.minItems = minItems;
-            this.maxItems = maxItems;
-        }
-
         public async Task ValidateAsync(object value, ValidationContext context, Action<string> addError)
         {
-            if (!(value is AssetsValue assets) || assets.AssetIds.Count == 0)
+            if (value is ICollection<Guid> assetIds)
             {
-                if (isRequired && !context.IsOptional)
+                var invalidIds = await context.GetInvalidAssetIdsAsync(assetIds);
+
+                foreach (var invalidId in invalidIds)
                 {
-                    addError("<FIELD> is required.");
+                    addError($"<FIELD> contains invalid asset '{invalidId}'.");
                 }
-
-                return;
-            }
-
-            if (minItems.HasValue && assets.AssetIds.Count < minItems.Value)
-            {
-                addError($"<FIELD> must have at least {minItems} asset(s).");
-            }
-
-            if (maxItems.HasValue && assets.AssetIds.Count > maxItems.Value)
-            {
-                addError($"<FIELD> must have not more than {maxItems} asset(s).");
-            }
-
-            var invalidIds = await context.GetInvalidAssetIdsAsync(assets.AssetIds);
-
-            foreach (var invalidId in invalidIds)
-            {
-                addError($"<FIELD> contains invalid asset '{invalidId}'.");
             }
         }
     }
diff --git a/src/Squidex.Domain.Apps.Core/Schemas/Validators/CollectionItemValidator.cs b/src/Squidex.Domain.Apps.Core/Schemas/Validators/CollectionItemValidator.cs
new file mode 100644
index 000000000..5417166d0
--- /dev/null
+++ b/src/Squidex.Domain.Apps.Core/Schemas/Validators/CollectionItemValidator.cs
@@ -0,0 +1,46 @@
+// ==========================================================================
+//  CollectionItemValidator.cs
+//  Squidex Headless CMS
+// ==========================================================================
+//  Copyright (c) Squidex Group
+//  All rights reserved.
+// ==========================================================================
+
+using System;
+using System.Collections.Generic;
+using System.Threading.Tasks;
+using Squidex.Infrastructure;
+
+namespace Squidex.Domain.Apps.Core.Schemas.Validators
+{
+    public sealed class CollectionItemValidator<T> : IValidator
+    {
+        private readonly IValidator[] itemValidators;
+
+        public CollectionItemValidator(params IValidator[] itemValidators)
+        {
+            Guard.NotNull(itemValidators, nameof(itemValidators));
+            Guard.NotEmpty(itemValidators, nameof(itemValidators));
+
+            this.itemValidators = itemValidators;
+        }
+
+        public async Task ValidateAsync(object value, ValidationContext context, Action<string> addError)
+        {
+            if (value is ICollection<T> items)
+            {
+                var index = 1;
+
+                foreach (var item in items)
+                {
+                    foreach (var itemValidator in itemValidators)
+                    {
+                        await itemValidator.ValidateAsync(item, context, e => addError(e.Replace("<FIELD>", $"<FIELD> item #{index}")));
+                    }
+
+                    index++;
+                }
+            }
+        }
+    }
+}
diff --git a/src/Squidex.Domain.Apps.Core/Schemas/Validators/CollectionValidator.cs b/src/Squidex.Domain.Apps.Core/Schemas/Validators/CollectionValidator.cs
new file mode 100644
index 000000000..95de4d88b
--- /dev/null
+++ b/src/Squidex.Domain.Apps.Core/Schemas/Validators/CollectionValidator.cs
@@ -0,0 +1,54 @@
+// ==========================================================================
+//  CollectionValidator.cs
+//  Squidex Headless CMS
+// ==========================================================================
+//  Copyright (c) Squidex Group
+//  All rights reserved.
+// ==========================================================================
+
+using System;
+using System.Collections.Generic;
+using System.Threading.Tasks;
+using Squidex.Infrastructure.Tasks;
+
+namespace Squidex.Domain.Apps.Core.Schemas.Validators
+{
+    public sealed class CollectionValidator<T> : IValidator
+    {
+        private readonly bool isRequired;
+        private readonly int? minItems;
+        private readonly int? maxItems;
+
+        public CollectionValidator(bool isRequired, int? minItems = null, int? maxItems = null)
+        {
+            this.isRequired = isRequired;
+            this.minItems = minItems;
+            this.maxItems = maxItems;
+        }
+
+        public Task ValidateAsync(object value, ValidationContext context, Action<string> addError)
+        {
+            if (!(value is ICollection<T> items) || items.Count == 0)
+            {
+                if (isRequired && !context.IsOptional)
+                {
+                    addError("<FIELD> is required.");
+                }
+
+                return TaskHelper.Done;
+            }
+
+            if (minItems.HasValue && items.Count < minItems.Value)
+            {
+                addError($"<FIELD> must have at least {minItems} item(s).");
+            }
+
+            if (maxItems.HasValue && items.Count > maxItems.Value)
+            {
+                addError($"<FIELD> must have not more than {maxItems} item(s).");
+            }
+
+            return TaskHelper.Done;
+        }
+    }
+}
diff --git a/src/Squidex.Domain.Apps.Core/Schemas/Validators/RangeValidator.cs b/src/Squidex.Domain.Apps.Core/Schemas/Validators/RangeValidator.cs
index 3d8dcca14..05132b2fc 100644
--- a/src/Squidex.Domain.Apps.Core/Schemas/Validators/RangeValidator.cs
+++ b/src/Squidex.Domain.Apps.Core/Schemas/Validators/RangeValidator.cs
@@ -39,12 +39,12 @@ namespace Squidex.Domain.Apps.Core.Schemas.Validators
 
             if (min.HasValue && typedValue.CompareTo(min.Value) < 0)
             {
-                addError($"<FIELD> must be greater than '{min}'.");
+                addError($"<FIELD> must be greater or equals than '{min}'.");
             }
 
             if (max.HasValue && typedValue.CompareTo(max.Value) > 0)
             {
-                addError($"<FIELD> must be less than '{max}'.");
+                addError($"<FIELD> must be less or equals than '{max}'.");
             }
 
             return TaskHelper.Done;
diff --git a/src/Squidex.Domain.Apps.Core/Schemas/Validators/ReferencesValidator.cs b/src/Squidex.Domain.Apps.Core/Schemas/Validators/ReferencesValidator.cs
index 54e583231..b5ddfaa47 100644
--- a/src/Squidex.Domain.Apps.Core/Schemas/Validators/ReferencesValidator.cs
+++ b/src/Squidex.Domain.Apps.Core/Schemas/Validators/ReferencesValidator.cs
@@ -7,52 +7,30 @@
 // ==========================================================================
 
 using System;
+using System.Collections.Generic;
 using System.Threading.Tasks;
 
 namespace Squidex.Domain.Apps.Core.Schemas.Validators
 {
     public sealed class ReferencesValidator : IValidator
     {
-        private readonly bool isRequired;
         private readonly Guid schemaId;
-        private readonly int? minItems;
-        private readonly int? maxItems;
 
-        public ReferencesValidator(bool isRequired, Guid schemaId, int? minItems = null, int? maxItems = null)
+        public ReferencesValidator(Guid schemaId)
         {
-            this.isRequired = isRequired;
             this.schemaId = schemaId;
-            this.minItems = minItems;
-            this.maxItems = maxItems;
         }
 
         public async Task ValidateAsync(object value, ValidationContext context, Action<string> addError)
         {
-            if (!(value is ReferencesValue references) || references.ContentIds.Count == 0)
+            if (value is ICollection<Guid> contentIds)
             {
-                if (isRequired && !context.IsOptional)
+                var invalidIds = await context.GetInvalidContentIdsAsync(contentIds, schemaId);
+
+                foreach (var invalidId in invalidIds)
                 {
-                    addError("<FIELD> is required.");
+                    addError($"<FIELD> contains invalid reference '{invalidId}'.");
                 }
-
-                return;
-            }
-
-            if (minItems.HasValue && references.ContentIds.Count < minItems.Value)
-            {
-                addError($"<FIELD> must have at least {minItems} reference(s).");
-            }
-
-            if (maxItems.HasValue && references.ContentIds.Count > maxItems.Value)
-            {
-                addError($"<FIELD> must have not more than {maxItems} reference(s).");
-            }
-
-            var invalidIds = await context.GetInvalidContentIdsAsync(references.ContentIds, schemaId);
-
-            foreach (var invalidId in invalidIds)
-            {
-                addError($"<FIELD> contains invalid reference '{invalidId}'.");
             }
         }
     }
diff --git a/tests/Squidex.Domain.Apps.Core.Tests/ContentValidationTests.cs b/tests/Squidex.Domain.Apps.Core.Tests/ContentValidationTests.cs
index f15b60ea1..54f8f0d0f 100644
--- a/tests/Squidex.Domain.Apps.Core.Tests/ContentValidationTests.cs
+++ b/tests/Squidex.Domain.Apps.Core.Tests/ContentValidationTests.cs
@@ -56,7 +56,7 @@ namespace Squidex.Domain.Apps.Core
             errors.ShouldBeEquivalentTo(
                 new List<ValidationError>
                 {
-                    new ValidationError("my-field must be less than '100'.", "my-field")
+                    new ValidationError("my-field must be less or equals than '100'.", "my-field")
                 });
         }
 
@@ -212,7 +212,7 @@ namespace Squidex.Domain.Apps.Core
             errors.ShouldBeEquivalentTo(
                 new List<ValidationError>
                 {
-                    new ValidationError("my-field must be less than '100'.", "my-field")
+                    new ValidationError("my-field must be less or equals than '100'.", "my-field")
                 });
         }
 
diff --git a/tests/Squidex.Domain.Apps.Core.Tests/Schemas/AssetsFieldTests.cs b/tests/Squidex.Domain.Apps.Core.Tests/Schemas/AssetsFieldTests.cs
index baa83cb62..3e293f939 100644
--- a/tests/Squidex.Domain.Apps.Core.Tests/Schemas/AssetsFieldTests.cs
+++ b/tests/Squidex.Domain.Apps.Core.Tests/Schemas/AssetsFieldTests.cs
@@ -99,7 +99,7 @@ namespace Squidex.Domain.Apps.Core.Schemas
             await sut.ValidateAsync(CreateValue(Guid.NewGuid(), Guid.NewGuid()), errors);
 
             errors.ShouldBeEquivalentTo(
-                new[] { "<FIELD> must have at least 3 asset(s)." });
+                new[] { "<FIELD> must have at least 3 item(s)." });
         }
 
         [Fact]
@@ -110,7 +110,7 @@ namespace Squidex.Domain.Apps.Core.Schemas
             await sut.ValidateAsync(CreateValue(Guid.NewGuid(), Guid.NewGuid()), errors);
 
             errors.ShouldBeEquivalentTo(
-                new[] { "<FIELD> must have not more than 1 asset(s)." });
+                new[] { "<FIELD> must have not more than 1 item(s)." });
         }
 
         [Fact]
@@ -206,14 +206,6 @@ namespace Squidex.Domain.Apps.Core.Schemas
             Assert.Same(token, result);
         }
 
-        [Fact]
-        public void Should_create_assets_value_with_empty_list_when_null()
-        {
-            var value = new AssetsValue(null);
-
-            Assert.Equal(new List<Guid>(), value.AssetIds);
-        }
-
         private static JToken CreateValue(params Guid[] ids)
         {
             return ids == null ? JValue.CreateNull() : (JToken)new JArray(ids.OfType<object>().ToArray());
diff --git a/tests/Squidex.Domain.Apps.Core.Tests/Schemas/DateTimeFieldTests.cs b/tests/Squidex.Domain.Apps.Core.Tests/Schemas/DateTimeFieldTests.cs
index 30c073a60..802cad054 100644
--- a/tests/Squidex.Domain.Apps.Core.Tests/Schemas/DateTimeFieldTests.cs
+++ b/tests/Squidex.Domain.Apps.Core.Tests/Schemas/DateTimeFieldTests.cs
@@ -65,7 +65,7 @@ namespace Squidex.Domain.Apps.Core.Schemas
             await sut.ValidateAsync(CreateValue(FutureDays(0)), errors);
 
             errors.ShouldBeEquivalentTo(
-                new[] { $"<FIELD> must be greater than '{FutureDays(10)}'." });
+                new[] { $"<FIELD> must be greater or equals than '{FutureDays(10)}'." });
         }
 
         [Fact]
@@ -76,7 +76,7 @@ namespace Squidex.Domain.Apps.Core.Schemas
             await sut.ValidateAsync(CreateValue(FutureDays(20)), errors);
 
             errors.ShouldBeEquivalentTo(
-                new[] { $"<FIELD> must be less than '{FutureDays(10)}'." });
+                new[] { $"<FIELD> must be less or equals than '{FutureDays(10)}'." });
         }
 
         [Fact]
diff --git a/tests/Squidex.Domain.Apps.Core.Tests/Schemas/NumberFieldTests.cs b/tests/Squidex.Domain.Apps.Core.Tests/Schemas/NumberFieldTests.cs
index 95cfa32c2..f631b0f64 100644
--- a/tests/Squidex.Domain.Apps.Core.Tests/Schemas/NumberFieldTests.cs
+++ b/tests/Squidex.Domain.Apps.Core.Tests/Schemas/NumberFieldTests.cs
@@ -64,7 +64,7 @@ namespace Squidex.Domain.Apps.Core.Schemas
             await sut.ValidateAsync(CreateValue(5), errors);
 
             errors.ShouldBeEquivalentTo(
-                new[] { "<FIELD> must be greater than '10'." });
+                new[] { "<FIELD> must be greater or equals than '10'." });
         }
 
         [Fact]
@@ -75,7 +75,7 @@ namespace Squidex.Domain.Apps.Core.Schemas
             await sut.ValidateAsync(CreateValue(20), errors);
 
             errors.ShouldBeEquivalentTo(
-                new[] { "<FIELD> must be less than '10'." });
+                new[] { "<FIELD> must be less or equals than '10'." });
         }
 
         [Fact]
diff --git a/tests/Squidex.Domain.Apps.Core.Tests/Schemas/ReferencesFieldTests.cs b/tests/Squidex.Domain.Apps.Core.Tests/Schemas/ReferencesFieldTests.cs
index 6864a0a4e..2a0ef8df8 100644
--- a/tests/Squidex.Domain.Apps.Core.Tests/Schemas/ReferencesFieldTests.cs
+++ b/tests/Squidex.Domain.Apps.Core.Tests/Schemas/ReferencesFieldTests.cs
@@ -100,7 +100,7 @@ namespace Squidex.Domain.Apps.Core.Schemas
             await sut.ValidateAsync(CreateValue(Guid.NewGuid(), Guid.NewGuid()), errors);
 
             errors.ShouldBeEquivalentTo(
-                new[] { "<FIELD> must have at least 3 reference(s)." });
+                new[] { "<FIELD> must have at least 3 item(s)." });
         }
 
         [Fact]
@@ -111,7 +111,7 @@ namespace Squidex.Domain.Apps.Core.Schemas
             await sut.ValidateAsync(CreateValue(Guid.NewGuid(), Guid.NewGuid()), errors);
 
             errors.ShouldBeEquivalentTo(
-                new[] { "<FIELD> must have not more than 1 reference(s)." });
+                new[] { "<FIELD> must have not more than 1 item(s)." });
         }
 
         [Fact]
@@ -220,14 +220,6 @@ namespace Squidex.Domain.Apps.Core.Schemas
             Assert.Same(token, result);
         }
 
-        [Fact]
-        public void Should_create_references_value_with_empty_list_when_null()
-        {
-            var value = new ReferencesValue(null);
-
-            Assert.Equal(new List<Guid>(), value.ContentIds);
-        }
-
         private static JToken CreateValue(params Guid[] ids)
         {
             return ids == null ? JValue.CreateNull() : (JToken)new JArray(ids.OfType<object>().ToArray());
diff --git a/tests/Squidex.Domain.Apps.Core.Tests/Schemas/Validators/CollectionItemValidatorTests.cs b/tests/Squidex.Domain.Apps.Core.Tests/Schemas/Validators/CollectionItemValidatorTests.cs
new file mode 100644
index 000000000..f0e64e2f3
--- /dev/null
+++ b/tests/Squidex.Domain.Apps.Core.Tests/Schemas/Validators/CollectionItemValidatorTests.cs
@@ -0,0 +1,55 @@
+// ==========================================================================
+//  CollectionValidatorTests.cs
+//  Squidex Headless CMS
+// ==========================================================================
+//  Copyright (c) Squidex Group
+//  All rights reserved.
+// ==========================================================================
+
+using System.Collections.Generic;
+using System.Threading.Tasks;
+using FluentAssertions;
+using Xunit;
+
+namespace Squidex.Domain.Apps.Core.Schemas.Validators
+{
+    public class CollectionItemValidatorTests
+    {
+        private readonly List<string> errors = new List<string>();
+
+        [Fact]
+        public async Task Should_not_add_error_if_value_is_wrong_type()
+        {
+            var sut = new CollectionItemValidator<int>(new RangeValidator<int>(2, 4));
+
+            await sut.ValidateAsync(true, errors);
+
+            Assert.Empty(errors);
+        }
+
+        [Fact]
+        public async Task Should_not_add_error_if_all_values_are_valid()
+        {
+            var sut = new CollectionItemValidator<int>(new RangeValidator<int>(2, 4));
+
+            await sut.ValidateAsync(new List<int> { 2, 3, 4 }, errors);
+
+            Assert.Empty(errors);
+        }
+
+        [Fact]
+        public async Task Should_add_error_if_at_least_one_item_is_not_valid()
+        {
+            var sut = new CollectionItemValidator<int>(new RangeValidator<int>(2, 4));
+
+            await sut.ValidateAsync(new List<int> { 2, 1, 4, 5 }, errors);
+
+            errors.ShouldBeEquivalentTo(
+                new[]
+                {
+                    "<FIELD> item #2 must be greater or equals than '2'.",
+                    "<FIELD> item #4 must be less or equals than '4'."
+                });
+        }
+    }
+}
diff --git a/tests/Squidex.Domain.Apps.Core.Tests/Schemas/Validators/CollectionValidatorTests.cs b/tests/Squidex.Domain.Apps.Core.Tests/Schemas/Validators/CollectionValidatorTests.cs
new file mode 100644
index 000000000..07eac3007
--- /dev/null
+++ b/tests/Squidex.Domain.Apps.Core.Tests/Schemas/Validators/CollectionValidatorTests.cs
@@ -0,0 +1,73 @@
+// ==========================================================================
+//  CollectionValidatorTests.cs
+//  Squidex Headless CMS
+// ==========================================================================
+//  Copyright (c) Squidex Group
+//  All rights reserved.
+// ==========================================================================
+
+using System.Collections.Generic;
+using System.Threading.Tasks;
+using FluentAssertions;
+using Xunit;
+
+namespace Squidex.Domain.Apps.Core.Schemas.Validators
+{
+    public class CollectionValidatorTests
+    {
+        private readonly List<string> errors = new List<string>();
+
+        [Fact]
+        public async Task Should_not_add_error_if_value_is_valid()
+        {
+            var sut = new CollectionValidator<int>(true, 1, 3);
+
+            await sut.ValidateAsync(new List<int> { 1, 2 }, errors);
+
+            Assert.Empty(errors);
+        }
+
+        [Fact]
+        public async Task Should_not_add_error_if_optional()
+        {
+            var sut = new CollectionValidator<int>(true, 1, 3);
+
+            await sut.ValidateOptionalAsync(null, errors);
+
+            Assert.Empty(errors);
+        }
+
+        [Fact]
+        public async Task Should_add_error_if_value_is_null()
+        {
+            var sut = new CollectionValidator<int>(true, 1, 3);
+
+            await sut.ValidateAsync(null, errors);
+
+            errors.ShouldBeEquivalentTo(
+                new[] { "<FIELD> is required." });
+        }
+
+        [Fact]
+        public async Task Should_add_error_if_collection_has_too_few_items()
+        {
+            var sut = new CollectionValidator<int>(true, 2, 3);
+
+            await sut.ValidateAsync(new List<int> { 1 }, errors);
+
+            errors.ShouldBeEquivalentTo(
+                new[] { "<FIELD> must have at least 2 item(s)." });
+        }
+
+        [Fact]
+        public async Task Should_add_error_if_collection_has_too_many_items()
+        {
+            var sut = new CollectionValidator<int>(true, 2, 3);
+
+            await sut.ValidateAsync(new List<int> { 1, 2, 3, 4 }, errors);
+
+            errors.ShouldBeEquivalentTo(
+                new[] { "<FIELD> must have not more than 3 item(s)." });
+        }
+    }
+}
diff --git a/tests/Squidex.Domain.Apps.Core.Tests/Schemas/Validators/RangeValidatorTests.cs b/tests/Squidex.Domain.Apps.Core.Tests/Schemas/Validators/RangeValidatorTests.cs
index 3eba5cbb5..fef036a4f 100644
--- a/tests/Squidex.Domain.Apps.Core.Tests/Schemas/Validators/RangeValidatorTests.cs
+++ b/tests/Squidex.Domain.Apps.Core.Tests/Schemas/Validators/RangeValidatorTests.cs
@@ -58,7 +58,7 @@ namespace Squidex.Domain.Apps.Core.Schemas.Validators
             await sut.ValidateAsync(1500, errors);
 
             errors.ShouldBeEquivalentTo(
-                new[] { "<FIELD> must be greater than '2000'." });
+                new[] { "<FIELD> must be greater or equals than '2000'." });
         }
 
         [Fact]
@@ -69,7 +69,7 @@ namespace Squidex.Domain.Apps.Core.Schemas.Validators
             await sut.ValidateAsync(1500, errors);
 
             errors.ShouldBeEquivalentTo(
-                new[] { "<FIELD> must be less than '1000'." });
+                new[] { "<FIELD> must be less or equals than '1000'." });
         }
     }
 }