Custom extension x-enumMetaData to expose title and description for an enum value.

src/NJsonSchema.Tests/Generation/EnumTests.cs

@@ -1,6 +1,8 @@
 using System;
 using System.Linq;
 using System.Collections.Generic;
+using System.ComponentModel;
+using System.ComponentModel.DataAnnotations;
 using System.Threading.Tasks;
 using Newtonsoft.Json;
 using Newtonsoft.Json.Converters;
@@ -107,9 +109,48 @@ public async Task When_SerializerSettings_has_CamelCase_StringEnumConverter_then
             Assert.Equal("Value2", schema.EnumerationNames.Last());
         }
 
-        [Flags]
-        public enum EnumWithFlags
+        [Fact]
+        public async Task When_ComponentModel_Attributes_are_not_used_meta_data_has_only_the_names()
+        {
+            // Arrange
+
+            // Act
+            var schema = JsonSchema.FromType<MyEnum>();
+            var json = schema.ToJson();
+
+            // Assert
+            Assert.Equal("Value1", schema.EnumerationMetaData.First().Title);
+            Assert.Equal("Value2", schema.EnumerationMetaData.Last().Title);
+
+            Assert.Null(schema.EnumerationMetaData.First().Description);
+            Assert.Null(schema.EnumerationMetaData.Last().Description);
+        }
+
+        public enum MyEnumWithAttributes {
+            [Display(Name = "My name 1", Description = "My description 1")] Value1,
+            [Description("My description 2")]
+            Value2
+        }
+
+        [Fact]
+        public async Task When_ComponentModel_Attributes_are_used_on_enum_values_its_used_in_meta_data()
         {
+            // Arrange
+
+            // Act
+            var schema = JsonSchema.FromType<MyEnumWithAttributes>();
+            var json = schema.ToJson();
+
+            // Assert
+            Assert.Equal("My name 1", schema.EnumerationMetaData.First().Title);
+            Assert.Equal("Value2", schema.EnumerationMetaData.Last().Title);
+
+            Assert.Equal("My description 1", schema.EnumerationMetaData.First().Description);
+            Assert.Equal("My description 2", schema.EnumerationMetaData.Last().Description);
+        }
+
+        [Flags]
+        public enum EnumWithFlags {
             Foo = 1,
             Bar = 2,
             Baz = 4,

src/NJsonSchema/Generation/EnumerationMetaData.cs

@@ -0,0 +1,23 @@
+using Newtonsoft.Json;
+
+namespace NJsonSchema.Generation {
+    /// <summary>
+    /// Additional meta data for enumerations.
+    /// </summary>
+    /// <remarks>
+    /// An enum value doesn't have a title or description associated with it in the JSON schema specification.
+    /// </remarks>
+    public class EnumerationMetaData {
+        /// <summary>
+        /// Surrogate for the "title" keyword as described in <see href="https://json-schema.org/draft/2020-12/json-schema-validation.html#rfc.section.9.1">the specification</see>.
+        /// </summary>
+        [JsonProperty("title", DefaultValueHandling = DefaultValueHandling.IgnoreAndPopulate, Order = 0)]
+        public string Title { get; set; }
+
+        /// <summary>
+        /// Surrogate for the "description" keyword as described in <see href="https://json-schema.org/draft/2020-12/json-schema-validation.html#rfc.section.9.1">the specification</see>.
+        /// </summary>
+        [JsonProperty("description", DefaultValueHandling = DefaultValueHandling.IgnoreAndPopulate, Order = 0)]
+        public string Description { get; set; }
+    }
+}

src/NJsonSchema/Generation/JsonSchemaGenerator.cs

@@ -351,15 +351,10 @@ public virtual void ApplyDataAnnotations(JsonSchema schema, JsonTypeDescription
         {
             var contextualType = typeDescription.ContextualType;
 
-            dynamic displayAttribute = contextualType.ContextAttributes.FirstAssignableToTypeNameOrDefault("System.ComponentModel.DataAnnotations.DisplayAttribute");
-            if (displayAttribute != null)
+            var name = contextualType.GetDisplayName();
+            if (name != null) 
             {
-                // GetName returns null if the Name property on the attribute is not specified.
-                var name = displayAttribute.GetName();
-                if (name != null) 
-                {
-                    schema.Title = name;
-                }
+                schema.Title = name;
             }
 
             dynamic defaultValueAttribute = contextualType.ContextAttributes.FirstAssignableToTypeNameOrDefault("System.ComponentModel.DefaultValueAttribute");
@@ -720,6 +715,13 @@ protected virtual void GenerateEnum(JsonSchema schema, JsonTypeDescription typeD
                     }
                 }
 
+                var contextualFieldType = contextualType.GetField(enumName);
+                schema.EnumerationMetaData.Add(new EnumerationMetaData
+                {
+                    Title = contextualFieldType?.GetDisplayName() ?? enumName,
+                    Description = contextualFieldType?.GetDescription()
+                });
+
                 schema.EnumerationNames.Add(enumName);
             }
 

src/NJsonSchema/Infrastructure/TypeExtensions.cs

@@ -56,6 +56,15 @@ private static string GetNameWithoutCache(ContextualMemberInfo member)
             return member.Name;
         }
 
+        /// <summary>Gets the name of the given member (based on the DisplayAttribute).</summary>
+        /// <returns>The name or null if no name is available.</returns>
+        public static string GetDisplayName(this ContextualType contextualType)
+        {
+            dynamic displayAttribute = contextualType.ContextAttributes.FirstAssignableToTypeNameOrDefault("System.ComponentModel.DataAnnotations.DisplayAttribute");
+            // GetName returns null if the Name property on the attribute is not specified.
+            return displayAttribute?.GetName();
+        }
+
         /// <summary>Gets the description of the given member (based on the DescriptionAttribute, DisplayAttribute or XML Documentation).</summary>
         /// <param name="type">The member info</param>
         /// <param name="attributeType">The attribute type to check.</param>

src/NJsonSchema/JsonSchema.Serialization.cs

@@ -16,6 +16,7 @@
 using Newtonsoft.Json;
 using Newtonsoft.Json.Linq;
 using NJsonSchema.Collections;
+using NJsonSchema.Generation;
 using NJsonSchema.Infrastructure;
 
 namespace NJsonSchema
@@ -131,6 +132,10 @@ internal object DiscriminatorRaw
         /// <summary>Gets or sets the enumeration names (optional, draft v5). </summary>
         [JsonIgnore]
         public Collection<string> EnumerationNames { get; set; }
+
+        /// <summary>Gets or sets the enumeration meta data (custom extension, sets 'x-enumMetaData').</summary>
+        [JsonIgnore]
+        public Collection<EnumerationMetaData> EnumerationMetaData { get; set; }
 
         /// <summary>Gets or sets a value indicating whether the maximum value is excluded. </summary>
         [JsonProperty("exclusiveMaximum", DefaultValueHandling = DefaultValueHandling.IgnoreAndPopulate)]
@@ -395,6 +400,14 @@ internal Collection<string> EnumerationNamesRaw
             set { EnumerationNames = value != null ? new ObservableCollection<string>(value) : new ObservableCollection<string>(); }
         }
 
+        /// <summary>Gets or sets the enumeration meta data (custom extension, sets 'x-enumMetaData').</summary>
+        [JsonProperty("x-enumMetaData", DefaultValueHandling = DefaultValueHandling.IgnoreAndPopulate)]
+        internal Collection<EnumerationMetaData> EnumerationMetaDataRaw
+        {
+            get { return EnumerationMetaData != null && EnumerationMetaData.Count > 0 ? EnumerationMetaData : null; }
+            set { EnumerationMetaData = value != null ? new ObservableCollection<EnumerationMetaData>(value) : new ObservableCollection<EnumerationMetaData>(); }
+        }
+
         [JsonProperty("enum", DefaultValueHandling = DefaultValueHandling.IgnoreAndPopulate)]
         internal ICollection<object> EnumerationRaw
         {

src/NJsonSchema/JsonSchema.cs

@@ -968,6 +968,11 @@ private void Initialize()
             {
                 EnumerationNames = new Collection<string>();
             }
+
+            if (EnumerationMetaData == null)
+            {
+                EnumerationMetaData = new Collection<EnumerationMetaData>();
+            }
         }
     }
 }