Immutable schemas.

src/Squidex.Domain.Apps.Core.Model/Schemas/AssetsFieldProperties.cs

@@ -6,6 +6,8 @@
 //  All rights reserved.
 // ==========================================================================
 
+using System.Collections.Generic;
+using Newtonsoft.Json.Linq;
 using Squidex.Infrastructure;
 
 namespace Squidex.Domain.Apps.Core.Schemas
@@ -13,9 +15,36 @@ namespace Squidex.Domain.Apps.Core.Schemas
     [TypeName(nameof(AssetsField))]
     public sealed class AssetsFieldProperties : FieldProperties
     {
-        public int? MinItems { get; set; }
+        private int? minItems;
+        private int? maxItems;
 
-        public int? MaxItems { get; set; }
+        public int? MinItems
+        {
+            get
+            {
+                return minItems;
+            }
+            set
+            {
+                ThrowIfFrozen();
+
+                minItems = value;
+            }
+        }
+
+        public int? MaxItems
+        {
+            get
+            {
+                return maxItems;
+            }
+            set
+            {
+                ThrowIfFrozen();
+
+                maxItems = value;
+            }
+        }
 
         public override T Accept<T>(IFieldPropertiesVisitor<T> visitor)
         {

src/Squidex.Domain.Apps.Core.Model/Schemas/BooleanFieldProperties.cs

@@ -6,6 +6,8 @@
 //  All rights reserved.
 // ==========================================================================
 
+using System.Collections.Generic;
+using Newtonsoft.Json.Linq;
 using Squidex.Infrastructure;
 
 namespace Squidex.Domain.Apps.Core.Schemas
@@ -13,9 +15,36 @@ namespace Squidex.Domain.Apps.Core.Schemas
     [TypeName(nameof(BooleanField))]
     public sealed class BooleanFieldProperties : FieldProperties
     {
-        public bool? DefaultValue { get; set; }
+        private BooleanFieldEditor editor;
+        private bool? defaultValue;
 
-        public BooleanFieldEditor Editor { get; set; }
+        public bool? DefaultValue
+        {
+            get
+            {
+                return defaultValue;
+            }
+            set
+            {
+                ThrowIfFrozen();
+
+                defaultValue = value;
+            }
+        }
+
+        public BooleanFieldEditor Editor
+        {
+            get
+            {
+                return editor;
+            }
+            set
+            {
+                ThrowIfFrozen();
+
+                editor = value;
+            }
+        }
 
         public override T Accept<T>(IFieldPropertiesVisitor<T> visitor)
         {

src/Squidex.Domain.Apps.Core.Model/Schemas/DateTimeFieldProperties.cs

@@ -6,6 +6,9 @@
 //  All rights reserved.
 // ==========================================================================
 
+using System;
+using System.Collections.Generic;
+using Newtonsoft.Json.Linq;
 using NodaTime;
 using Squidex.Infrastructure;
 
@@ -14,15 +17,81 @@ namespace Squidex.Domain.Apps.Core.Schemas
     [TypeName(nameof(DateTimeField))]
     public sealed class DateTimeFieldProperties : FieldProperties
     {
-        public Instant? MaxValue { get; set; }
+        private DateTimeFieldEditor editor;
+        private DateTimeCalculatedDefaultValue? calculatedDefaultValue;
+        private Instant? maxValue;
+        private Instant? minValue;
+        private Instant? defaultValue;
 
-        public Instant? MinValue { get; set; }
+        public Instant? MaxValue
+        {
+            get
+            {
+                return maxValue;
+            }
+            set
+            {
+                ThrowIfFrozen();
+
+                maxValue = value;
+            }
+        }
+
+        public Instant? MinValue
+        {
+            get
+            {
+                return minValue;
+            }
+            set
+            {
+                ThrowIfFrozen();
+
+                minValue = value;
+            }
+        }
+
+        public Instant? DefaultValue
+        {
+            get
+            {
+                return defaultValue;
+            }
+            set
+            {
+                ThrowIfFrozen();
+
+                defaultValue = value;
+            }
+        }
+
+        public DateTimeCalculatedDefaultValue? CalculatedDefaultValue
+        {
+            get
+            {
+                return calculatedDefaultValue;
+            }
+            set
+            {
+                ThrowIfFrozen();
 
-        public Instant? DefaultValue { get; set; }
+                calculatedDefaultValue = value;
+            }
+        }
 
-        public DateTimeFieldEditor Editor { get; set; }
+        public DateTimeFieldEditor Editor
+        {
+            get
+            {
+                return editor;
+            }
+            set
+            {
+                ThrowIfFrozen();
 
-        public DateTimeCalculatedDefaultValue? CalculatedDefaultValue { get; set; }
+                editor = value;
+            }
+        }
 
         public override T Accept<T>(IFieldPropertiesVisitor<T> visitor)
         {

src/Squidex.Domain.Apps.Core.Model/Schemas/Field.cs

@@ -6,11 +6,12 @@
 //  All rights reserved.
 // ==========================================================================
 
+using System.Diagnostics.Contracts;
 using Squidex.Infrastructure;
 
 namespace Squidex.Domain.Apps.Core.Schemas
 {
-    public abstract class Field
+    public abstract class Field : Cloneable<Field>
     {
         private readonly long fieldId;
         private readonly Partitioning partitioning;
@@ -63,32 +64,52 @@ namespace Squidex.Domain.Apps.Core.Schemas
             this.partitioning = partitioning;
         }
 
-        public void Lock()
+        [Pure]
+        public Field Lock()
         {
-            isLocked = true;
+            return Clone<Field>(clone =>
+            {
+                clone.isLocked = true;
+            });
         }
 
-        public void Hide()
+        [Pure]
+        public Field Hide()
         {
-            isHidden = true;
+            return Clone(clone =>
+            {
+                clone.isHidden = true;
+            });
         }
 
-        public void Show()
+        [Pure]
+        public Field Show()
         {
-            isHidden = false;
+            return Clone(clone =>
+            {
+                clone.isHidden = false;
+            });
         }
 
-        public void Disable()
+        [Pure]
+        public Field Disable()
         {
-            isDisabled = true;
+            return Clone(clone =>
+            {
+                clone.isDisabled = true;
+            });
         }
 
-        public void Enable()
+        [Pure]
+        public Field Enable()
         {
-            isDisabled = false;
+            return Clone(clone =>
+            {
+                clone.isDisabled = false;
+            });
         }
 
-        public abstract void Update(FieldProperties newProperties);
+        public abstract Field Update(FieldProperties newProperties);
 
         public abstract T Accept<T>(IFieldVisitor<T> visitor);
     }

src/Squidex.Domain.Apps.Core.Model/Schemas/FieldProperties.cs

@@ -10,11 +10,51 @@ namespace Squidex.Domain.Apps.Core.Schemas
 {
     public abstract class FieldProperties : NamedElementPropertiesBase
     {
-        public bool IsRequired { get; set; }
+        private bool isRequired;
+        private bool isListField;
+        private string placeholder;
 
-        public bool IsListField { get; set; }
+        public bool IsRequired
+        {
+            get
+            {
+                return isRequired;
+            }
+            set
+            {
+                ThrowIfFrozen();
 
-        public string Placeholder { get; set; }
+                isRequired = value;
+            }
+        }
+
+        public bool IsListField
+        {
+            get
+            {
+                return isListField;
+            }
+            set
+            {
+                ThrowIfFrozen();
+
+                isListField = value;
+            }
+        }
+
+        public string Placeholder
+        {
+            get
+            {
+                return placeholder;
+            }
+            set
+            {
+                ThrowIfFrozen();
+
+                placeholder = value;
+            }
+        }
 
         public abstract T Accept<T>(IFieldPropertiesVisitor<T> visitor);
     }

src/Squidex.Domain.Apps.Core.Model/Schemas/Field{T}.cs

@@ -1,5 +1,5 @@
 // ==========================================================================
-//  Field_Generic.cs
+//  Field{T}.cs
 //  Squidex Headless CMS
 // ==========================================================================
 //  Copyright (c) Squidex Group
@@ -7,7 +7,9 @@
 // ==========================================================================
 
 using System;
+using System.Diagnostics.Contracts;
 using Squidex.Infrastructure;
+
 namespace Squidex.Domain.Apps.Core.Schemas
 {
     public abstract class Field<T> : Field where T : FieldProperties, new()
@@ -30,13 +32,19 @@ namespace Squidex.Domain.Apps.Core.Schemas
             Guard.NotNull(properties, nameof(properties));
 
             this.properties = properties;
+            this.properties.Freeze();
         }
 
-        public override void Update(FieldProperties newProperties)
+        [Pure]
+        public override Field Update(FieldProperties newProperties)
         {
             var typedProperties = ValidateProperties(newProperties);
 
-            properties = typedProperties;
+            return Clone<Field>(clone =>
+            {
+                properties = typedProperties;
+                properties.Freeze();
+            });
         }
 
         private T ValidateProperties(FieldProperties newProperties)

src/Squidex.Domain.Apps.Core.Model/Schemas/GeolocationFieldProperties.cs

@@ -6,6 +6,8 @@
 //  All rights reserved.
 // ==========================================================================
 
+using System.Collections.Generic;
+using Newtonsoft.Json.Linq;
 using Squidex.Infrastructure;
 
 namespace Squidex.Domain.Apps.Core.Schemas
@@ -13,7 +15,21 @@ namespace Squidex.Domain.Apps.Core.Schemas
     [TypeName(nameof(GeolocationField))]
     public sealed class GeolocationFieldProperties : FieldProperties
     {
-        public GeolocationFieldEditor Editor { get; set; }
+        private GeolocationFieldEditor editor;
+
+        public GeolocationFieldEditor Editor
+        {
+            get
+            {
+                return editor;
+            }
+            set
+            {
+                ThrowIfFrozen();
+
+                editor = value;
+            }
+        }
 
         public override T Accept<T>(IFieldPropertiesVisitor<T> visitor)
         {

src/Squidex.Domain.Apps.Core.Model/Schemas/Json/JsonSchemaModel.cs

@@ -54,7 +54,7 @@ namespace Squidex.Domain.Apps.Core.Schemas.Json
 
         public Schema ToSchema(FieldRegistry fieldRegistry)
         {
-            var schema = new Schema(Name);
+            var fields = new List<Field>();
 
             if (Fields != null)
             {
@@ -66,34 +66,24 @@ namespace Squidex.Domain.Apps.Core.Schemas.Json
 
                     if (fieldModel.IsDisabled)
                     {
-                        field.Disable();
+                        field = field.Disable();
                     }
 
                     if (fieldModel.IsLocked)
                     {
-                        field.Lock();
+                        field = field.Lock();
                     }
 
                     if (fieldModel.IsHidden)
                     {
-                        field.Hide();
+                        field = field.Hide();
                     }
 
-                    schema.AddField(field);
+                    fields.Add(field);
                 }
             }
 
-            if (IsPublished)
+            return new Schema(Name, fields, Properties, IsPublished);
-            {
-                schema.Publish();
-            }
-
-            if (Properties != null)
-            {
-                schema.Update(Properties);
-            }
-
-            return schema;
         }
     }
 }

src/Squidex.Domain.Apps.Core.Model/Schemas/JsonFieldProperties.cs

@@ -6,6 +6,8 @@
 //  All rights reserved.
 // ==========================================================================
 
+using System.Collections.Generic;
+using Newtonsoft.Json.Linq;
 using Squidex.Infrastructure;
 
 namespace Squidex.Domain.Apps.Core.Schemas

src/Squidex.Domain.Apps.Core.Model/Schemas/NamedElementPropertiesBase.cs

@@ -6,12 +6,41 @@
 //  All rights reserved.
 // ==========================================================================
 
+using Squidex.Infrastructure;
+
 namespace Squidex.Domain.Apps.Core.Schemas
 {
-    public abstract class NamedElementPropertiesBase
+    public abstract class NamedElementPropertiesBase : Freezable
     {
-        public string Label { get; set; }
+        private string label;
+        private string hints;
+
+        public string Label
+        {
+            get
+            {
+                return label;
+            }
+            set
+            {
+                ThrowIfFrozen();
+
+                label = value;
+            }
+        }
+
+        public string Hints
+        {
+            get
+            {
+                return hints;
+            }
+            set
+            {
+                ThrowIfFrozen();
 
-        public string Hints { get; set; }
+                hints = value;
+            }
+        }
     }
 }

src/Squidex.Domain.Apps.Core.Model/Schemas/NumberFieldProperties.cs

@@ -6,6 +6,9 @@
 //  All rights reserved.
 // ==========================================================================
 
+using System.Collections.Generic;
+using System.Collections.Immutable;
+using Newtonsoft.Json.Linq;
 using Squidex.Infrastructure;
 
 namespace Squidex.Domain.Apps.Core.Schemas
@@ -13,15 +16,81 @@ namespace Squidex.Domain.Apps.Core.Schemas
     [TypeName(nameof(NumberField))]
     public sealed class NumberFieldProperties : FieldProperties
     {
-        public double? MaxValue { get; set; }
+        private double? maxValue;
+        private double? minValue;
+        private double? defaultValue;
+        private ImmutableList<double> allowedValues;
+        private NumberFieldEditor editor;
 
-        public double? MinValue { get; set; }
+        public double? MaxValue
+        {
+            get
+            {
+                return maxValue;
+            }
+            set
+            {
+                ThrowIfFrozen();
+
+                maxValue = value;
+            }
+        }
+
+        public double? MinValue
+        {
+            get
+            {
+                return minValue;
+            }
+            set
+            {
+                ThrowIfFrozen();
+
+                minValue = value;
+            }
+        }
+
+        public double? DefaultValue
+        {
+            get
+            {
+                return defaultValue;
+            }
+            set
+            {
+                ThrowIfFrozen();
+
+                defaultValue = value;
+            }
+        }
+
+        public ImmutableList<double> AllowedValues
+        {
+            get
+            {
+                return allowedValues;
+            }
+            set
+            {
+                ThrowIfFrozen();
 
-        public double? DefaultValue { get; set; }
+                allowedValues = value;
+            }
+        }
 
-        public double[] AllowedValues { get; set; }
+        public NumberFieldEditor Editor
+        {
+            get
+            {
+                return editor;
+            }
+            set
+            {
+                ThrowIfFrozen();
 
-        public NumberFieldEditor Editor { get; set; }
+                editor = value;
+            }
+        }
 
         public override T Accept<T>(IFieldPropertiesVisitor<T> visitor)
         {

src/Squidex.Domain.Apps.Core.Model/Schemas/ReferencesFieldProperties.cs

@@ -7,6 +7,8 @@
 // ==========================================================================
 
 using System;
+using System.Collections.Generic;
+using Newtonsoft.Json.Linq;
 using Squidex.Infrastructure;
 
 namespace Squidex.Domain.Apps.Core.Schemas
@@ -14,11 +16,51 @@ namespace Squidex.Domain.Apps.Core.Schemas
     [TypeName(nameof(ReferencesField))]
     public sealed class ReferencesFieldProperties : FieldProperties
     {
-        public int? MinItems { get; set; }
+        private int? minItems;
+        private int? maxItems;
+        private Guid schemaId;
 
-        public int? MaxItems { get; set; }
+        public int? MinItems
+        {
+            get
+            {
+                return minItems;
+            }
+            set
+            {
+                ThrowIfFrozen();
+
+                minItems = value;
+            }
+        }
+
+        public int? MaxItems
+        {
+            get
+            {
+                return maxItems;
+            }
+            set
+            {
+                ThrowIfFrozen();
 
-        public Guid SchemaId { get; set; }
+                maxItems = value;
+            }
+        }
+
+        public Guid SchemaId
+        {
+            get
+            {
+                return schemaId;
+            }
+            set
+            {
+                ThrowIfFrozen();
+
+                schemaId = value;
+            }
+        }
 
         public override T Accept<T>(IFieldPropertiesVisitor<T> visitor)
         {

src/Squidex.Domain.Apps.Core.Model/Schemas/Schema.cs

@@ -8,17 +8,19 @@
 
 using System;
 using System.Collections.Generic;
+using System.Collections.Immutable;
+using System.Diagnostics.Contracts;
 using System.Linq;
 using Squidex.Infrastructure;
 
 namespace Squidex.Domain.Apps.Core.Schemas
 {
-    public sealed class Schema
+    public sealed class Schema : Cloneable<Schema>
     {
         private readonly string name;
-        private readonly List<Field> fieldsOrdered = new List<Field>();
+        private ImmutableList<Field> fieldsOrdered = ImmutableList<Field>.Empty;
-        private readonly Dictionary<long, Field> fieldsById = new Dictionary<long, Field>();
+        private ImmutableDictionary<long, Field> fieldsById = ImmutableDictionary<long, Field>.Empty;
-        private readonly Dictionary<string, Field> fieldsByName = new Dictionary<string, Field>();
+        private ImmutableDictionary<string, Field> fieldsByName = ImmutableDictionary<string, Field>.Empty;
         private SchemaProperties properties = new SchemaProperties();
         private bool isPublished;
 
@@ -52,43 +54,132 @@ namespace Squidex.Domain.Apps.Core.Schemas
             get { return properties; }
         }
 
-        public void Publish()
+        public Schema(string name)
         {
-            isPublished = true;
+            Guard.NotNullOrEmpty(name, nameof(name));
-        }
 
-        public void Unpublish()
+            this.name = name;
-        {
-            isPublished = false;
         }
 
-        public Schema(string name)
+        public Schema(string name, IEnumerable<Field> fields, SchemaProperties properties, bool isPublished)
+            : this(name)
         {
             Guard.NotNullOrEmpty(name, nameof(name));
 
-            this.name = name;
+            this.isPublished = isPublished;
+
+            this.properties = properties ?? new SchemaProperties();
+            this.properties.Freeze();
+
+            fieldsOrdered = ImmutableList<Field>.Empty.AddRange(fields);
+        }
+
+        protected override void OnCloned()
+        {
+            fieldsById = fieldsOrdered.ToImmutableDictionary(x => x.Id);
+            fieldsByName = fieldsOrdered.ToImmutableDictionary(x => x.Name);
         }
 
-        public void Update(SchemaProperties newProperties)
+        [Pure]
+        public Schema Update(SchemaProperties newProperties)
         {
             Guard.NotNull(newProperties, nameof(newProperties));
 
-            properties = newProperties;
+            return Clone(clone =>
+            {
+                properties = newProperties;
+                properties.Freeze();
+            });
+        }
+
+        [Pure]
+        public Schema UpdateField(long fieldId, FieldProperties newProperties)
+        {
+            return UpdateField(fieldId, field =>
+            {
+                return field.Update(newProperties);
+            });
+        }
+
+        [Pure]
+        public Schema LockField(long fieldId)
+        {
+            return UpdateField(fieldId, field =>
+            {
+                return field.Lock();
+            });
+        }
+
+        [Pure]
+        public Schema DisableField(long fieldId)
+        {
+            return UpdateField(fieldId, field =>
+            {
+                return field.Disable();
+            });
+        }
+
+        [Pure]
+        public Schema EnableField(long fieldId)
+        {
+            return UpdateField(fieldId, field =>
+            {
+                return field.Enable();
+            });
+        }
+
+        [Pure]
+        public Schema HideField(long fieldId)
+        {
+            return UpdateField(fieldId, field =>
+            {
+                return field.Hide();
+            });
+        }
+
+        [Pure]
+        public Schema ShowField(long fieldId)
+        {
+            return UpdateField(fieldId, field =>
+            {
+                return field.Show();
+            });
         }
 
-        public void DeleteField(long fieldId)
+        [Pure]
+        public Schema Publish()
+        {
+            return Clone(clone =>
+            {
+                isPublished = true;
+            });
+        }
+
+        [Pure]
+        public Schema Unpublish()
+        {
+            return Clone(clone =>
+            {
+                isPublished = false;
+            });
+        }
+
+        [Pure]
+        public Schema DeleteField(long fieldId)
         {
             if (!fieldsById.TryGetValue(fieldId, out var field))
             {
-                return;
+                return this;
             }
 
-            fieldsById.Remove(fieldId);
+            return Clone(clone =>
-            fieldsByName.Remove(field.Name);
+            {
-            fieldsOrdered.Remove(field);
+                clone.fieldsOrdered = fieldsOrdered.Remove(field);
+            });
         }
 
-        public void ReorderFields(List<long> ids)
+        [Pure]
+        public Schema ReorderFields(List<long> ids)
         {
             Guard.NotNull(ids, nameof(ids));
 
@@ -97,13 +188,14 @@ namespace Squidex.Domain.Apps.Core.Schemas
                 throw new ArgumentException("Ids must cover all fields.", nameof(ids));
             }
 
-            var fields = fieldsOrdered.ToList();
+            return Clone(clone =>
-
+            {
-            fieldsOrdered.Clear();
+                clone.fieldsOrdered = fieldsOrdered.OrderBy(f => ids.IndexOf(f.Id)).ToImmutableList();
-            fieldsOrdered.AddRange(fields.OrderBy(f => ids.IndexOf(f.Id)));
+            });
         }
 
-        public void AddField(Field field)
+        [Pure]
+        public Schema AddField(Field field)
         {
             Guard.NotNull(field, nameof(field));
 
@@ -112,9 +204,26 @@ namespace Squidex.Domain.Apps.Core.Schemas
                 throw new ArgumentException($"A field with name '{field.Name}' already exists.", nameof(field));
             }
 
-            fieldsById.Add(field.Id, field);
+            return Clone(clone =>
-            fieldsByName.Add(field.Name, field);
+            {
-            fieldsOrdered.Add(field);
+                clone.fieldsOrdered = clone.fieldsOrdered.Add(field);
+            });
+        }
+
+        [Pure]
+        public Schema UpdateField(long fieldId, Func<Field, Field> updater)
+        {
+            Guard.NotNull(updater, nameof(updater));
+
+            if (!fieldsById.TryGetValue(fieldId, out var field))
+            {
+                return this;
+            }
+
+            return Clone(clone =>
+            {
+                clone.fieldsOrdered = clone.fieldsOrdered.Replace(field, updater(field));
+            });
         }
     }
 }

src/Squidex.Domain.Apps.Core.Model/Schemas/StringFieldProperties.cs

@@ -6,26 +6,122 @@
 //  All rights reserved.
 // ==========================================================================
 
+using System.Collections.Generic;
+using System.Collections.Immutable;
+using Newtonsoft.Json.Linq;
 using Squidex.Infrastructure;
+using Squidex.Infrastructure.Json;
 
 namespace Squidex.Domain.Apps.Core.Schemas
 {
     [TypeName(nameof(StringField))]
     public sealed class StringFieldProperties : FieldProperties
     {
-        public int? MinLength { get; set; }
+        private int? minLength;
+        private int? maxLength;
+        private string pattern;
+        private string patternMessage;
+        private string defaultValue;
+        private ImmutableList<string> allowedValues;
+        private StringFieldEditor editor;
 
-        public int? MaxLength { get; set; }
+        public int? MinLength
+        {
+            get
+            {
+                return minLength;
+            }
+            set
+            {
+                ThrowIfFrozen();
+
+                minLength = value;
+            }
+        }
+
+        public int? MaxLength
+        {
+            get
+            {
+                return maxLength;
+            }
+            set
+            {
+                ThrowIfFrozen();
+
+                maxLength = value;
+            }
+        }
+
+        public string DefaultValue
+        {
+            get
+            {
+                return defaultValue;
+            }
+            set
+            {
+                ThrowIfFrozen();
+
+                defaultValue = value;
+            }
+        }
 
-        public string DefaultValue { get; set; }
+        public string Pattern
+        {
+            get
+            {
+                return pattern;
+            }
+            set
+            {
+                ThrowIfFrozen();
+
+                pattern = value;
+            }
+        }
 
-        public string Pattern { get; set; }
+        public string PatternMessage
+        {
+            get
+            {
+                return patternMessage;
+            }
+            set
+            {
+                ThrowIfFrozen();
 
-        public string PatternMessage { get; set; }
+                patternMessage = value;
+            }
+        }
 
-        public string[] AllowedValues { get; set; }
+        public ImmutableList<string> AllowedValues
+        {
+            get
+            {
+                return allowedValues;
+            }
+            set
+            {
+                ThrowIfFrozen();
 
-        public StringFieldEditor Editor { get; set; }
+                allowedValues = value;
+            }
+        }
+
+        public StringFieldEditor Editor
+        {
+            get
+            {
+                return editor;
+            }
+            set
+            {
+                ThrowIfFrozen();
+
+                editor = value;
+            }
+        }
 
         public override T Accept<T>(IFieldPropertiesVisitor<T> visitor)
         {

src/Squidex.Domain.Apps.Core.Model/Schemas/TagsFieldProperties.cs

@@ -13,9 +13,36 @@ namespace Squidex.Domain.Apps.Core.Schemas
     [TypeName(nameof(TagsField))]
     public sealed class TagsFieldProperties : FieldProperties
     {
-        public int? MinItems { get; set; }
+        private int? minItems;
+        private int? maxItems;
 
-        public int? MaxItems { get; set; }
+        public int? MinItems
+        {
+            get
+            {
+                return minItems;
+            }
+            set
+            {
+                ThrowIfFrozen();
+
+                minItems = value;
+            }
+        }
+
+        public int? MaxItems
+        {
+            get
+            {
+                return maxItems;
+            }
+            set
+            {
+                ThrowIfFrozen();
+
+                maxItems = value;
+            }
+        }
 
         public override T Accept<T>(IFieldPropertiesVisitor<T> visitor)
         {

tests/Squidex.Domain.Apps.Core.Tests/Operations/ValidateContent/NumberFieldTests.cs

@@ -7,6 +7,7 @@
 // ==========================================================================
 
 using System.Collections.Generic;
+using System.Collections.Immutable;
 using System.Threading.Tasks;
 using FluentAssertions;
 using Newtonsoft.Json.Linq;
@@ -73,7 +74,7 @@ namespace Squidex.Domain.Apps.Core.Operations.ValidateContent
         [Fact]
         public async Task Should_add_errors_if_number_is_not_allowed()
         {
-            var sut = new NumberField(1, "my-number", Partitioning.Invariant, new NumberFieldProperties { AllowedValues = new[] { 10d } });
+            var sut = new NumberField(1, "my-number", Partitioning.Invariant, new NumberFieldProperties { AllowedValues = ImmutableList.Create(10d) });
 
             await sut.ValidateAsync(CreateValue(20), errors);
 

tests/Squidex.Domain.Apps.Core.Tests/Operations/ValidateContent/StringFieldTests.cs

@@ -7,6 +7,7 @@
 // ==========================================================================
 
 using System.Collections.Generic;
+using System.Collections.Immutable;
 using System.Threading.Tasks;
 using FluentAssertions;
 using Newtonsoft.Json.Linq;
@@ -73,7 +74,7 @@ namespace Squidex.Domain.Apps.Core.Operations.ValidateContent
         [Fact]
         public async Task Should_add_errors_if_string_not_allowed()
         {
-            var sut = new StringField(1, "my-string", Partitioning.Invariant, new StringFieldProperties { AllowedValues = new[] { "Foo" } });
+            var sut = new StringField(1, "my-string", Partitioning.Invariant, new StringFieldProperties { AllowedValues = ImmutableList.Create("Foo") });
 
             await sut.ValidateAsync(CreateValue("Bar"), errors);
 

tests/Squidex.Domain.Apps.Core.Tests/TestData.cs

@@ -6,6 +6,7 @@
 //  All rights reserved.
 // ==========================================================================
 
+using System.Collections.Immutable;
 using Newtonsoft.Json;
 using Newtonsoft.Json.Converters;
 using Squidex.Domain.Apps.Core.Apps.Json;
@@ -53,45 +54,45 @@ namespace Squidex.Domain.Apps.Core
 
             var schema = new Schema("user");
 
-            schema.Publish();
+            schema = schema.Publish();
-            schema.Update(new SchemaProperties { Hints = "The User" });
+            schema = schema.Update(new SchemaProperties { Hints = "The User" });
 
-            schema.AddField(new JsonField(1, "my-json", inv,
+            schema = schema.AddField(new JsonField(1, "my-json", inv,
                 new JsonFieldProperties()));
 
-            schema.AddField(new AssetsField(2, "my-assets", inv,
+            schema = schema.AddField(new AssetsField(2, "my-assets", inv,
                 new AssetsFieldProperties()));
 
-            schema.AddField(new StringField(3, "my-string1", inv,
+            schema = schema.AddField(new StringField(3, "my-string1", inv,
-                new StringFieldProperties { Label = "My String1", IsRequired = true, AllowedValues = new[] { "a", "b" } }));
+                new StringFieldProperties { Label = "My String1", IsRequired = true, AllowedValues = ImmutableList.Create("a", "b") }));
 
-            schema.AddField(new StringField(4, "my-string2", inv,
+            schema = schema.AddField(new StringField(4, "my-string2", inv,
                 new StringFieldProperties { Hints = "My String1" }));
 
-            schema.AddField(new NumberField(5, "my-number", inv,
+            schema = schema.AddField(new NumberField(5, "my-number", inv,
                 new NumberFieldProperties { MinValue = 1, MaxValue = 10 }));
 
-            schema.AddField(new BooleanField(6, "my-boolean", inv,
+            schema = schema.AddField(new BooleanField(6, "my-boolean", inv,
                 new BooleanFieldProperties()));
 
-            schema.AddField(new DateTimeField(7, "my-datetime", inv,
+            schema = schema.AddField(new DateTimeField(7, "my-datetime", inv,
                 new DateTimeFieldProperties { Editor = DateTimeFieldEditor.DateTime }));
 
-            schema.AddField(new DateTimeField(8, "my-date", inv,
+            schema = schema.AddField(new DateTimeField(8, "my-date", inv,
                 new DateTimeFieldProperties { Editor = DateTimeFieldEditor.Date }));
 
-            schema.AddField(new GeolocationField(9, "my-geolocation", inv,
+            schema = schema.AddField(new GeolocationField(9, "my-geolocation", inv,
                 new GeolocationFieldProperties()));
 
-            schema.AddField(new ReferencesField(10, "my-references", inv,
+            schema = schema.AddField(new ReferencesField(10, "my-references", inv,
                 new ReferencesFieldProperties()));
 
-            schema.AddField(new TagsField(11, "my-tags", Partitioning.Language,
+            schema = schema.AddField(new TagsField(11, "my-tags", Partitioning.Language,
                 new TagsFieldProperties()));
 
-            schema.FieldsById[7].Hide();
+            schema = schema.HideField(7);
-            schema.FieldsById[8].Disable();
+            schema = schema.LockField(8);
-            schema.FieldsById[9].Lock();
+            schema = schema.DisableField(9);
 
             return schema;
         }