Support EnumDataType annotation in JSON schema generation

src/NJsonSchema.Tests/Generation/EnumGenerationTests.cs

@@ -231,5 +231,39 @@ public async Task When_enum_property_is_required_then_MinLength_is_not_set()
             Assert.True(schema.Properties["Bar"].OneOf.Count == 0);
             Assert.True(schema.Properties["Bar"].Reference != null);
         }
+
+        public class ClassWithEnumDataTypeOnString
+        {
+            [EnumDataType(typeof(Bar))]
+            public string BarValue { get; set; }
+        }
+
+        public class ClassWithEnumDataTypeOnInt
+        {
+            [EnumDataType(typeof(Bar))]
+            public int BarValue { get; set; }
+        }
+
+        [Fact]
+        public async Task When_string_property_has_EnumDataType_annotation_then_schema_has_enum()
+        {
+            // Arrange & Act
+            var schema = NewtonsoftJsonSchemaGenerator.FromType<ClassWithEnumDataTypeOnString>(new NewtonsoftJsonSchemaGeneratorSettings());
+
+            // Assert
+            Assert.True(schema.Properties["BarValue"].ActualTypeSchema.IsEnumeration);
+            Assert.Equal(3, schema.Properties["BarValue"].ActualTypeSchema.Enumeration.Count);
+        }
+
+        [Fact]
+        public async Task When_int_property_has_EnumDataType_annotation_then_schema_has_enum()
+        {
+            // Arrange & Act
+            var schema = NewtonsoftJsonSchemaGenerator.FromType<ClassWithEnumDataTypeOnInt>(new NewtonsoftJsonSchemaGeneratorSettings());
+
+            // Assert
+            Assert.True(schema.Properties["BarValue"].ActualTypeSchema.IsEnumeration);
+            Assert.Equal(3, schema.Properties["BarValue"].ActualTypeSchema.Enumeration.Count);
+        }
     }
 }

src/NJsonSchema/Generation/ReflectionServiceBase.cs

@@ -51,6 +51,18 @@ public JsonTypeDescription GetDescription(ContextualType contextualType, Referen
                 }
             }
 
+            dynamic? enumDataTypeAttribute = contextualType.GetContextAttributes(true)
+                .FirstAssignableToTypeNameOrDefault("System.ComponentModel.DataAnnotations.EnumDataTypeAttribute");
+            if (enumDataTypeAttribute != null)
+            {
+                var enumType = (Type)enumDataTypeAttribute.EnumType;
+                if (enumType != null && enumType.IsEnum)
+                {
+                    type = enumType;
+                    contextualType = enumType.ToContextualType();
+                }
+            }
+
             var jsonSchemaAttribute = contextualType.GetContextOrTypeAttribute<JsonSchemaAttribute>(true); ;
             if (jsonSchemaAttribute != null)
             {