fix: enable validation rules to also be placed on classes (#1128)

fixes #1122

Author: kimpenhaus

docs/docs/operator/building-blocks/entities.mdx

@@ -137,7 +137,7 @@ public class EntitySpec
 - `[RangeMinimum]` and `[RangeMaximum]`: Defines numeric value ranges
 - `[MultipleOf]`: Specifies that a number must be a multiple of a given value
 - `[Items]`: Defines minimum and maximum items for arrays
-- `[ValidationRule]`: Defines custom validation rules using CEL expressions
+- `[ValidationRule]`: Defines custom validation rules using CEL expressions. Can be applied to properties and to class types — in both cases it emits `x-kubernetes-validations` on the corresponding schema node. When applied to both a class and a property of that type, the rules are merged (class rules first, then property rules)
 
 ### Documentation Attributes
 

src/KubeOps.Abstractions/Entities/Attributes/ValidationRuleAttribute.cs

@@ -37,7 +37,7 @@ namespace KubeOps.Abstractions.Entities.Attributes;
 /// <param name="reason">
 /// reason provides a machine-readable validation failure reason that is returned to the caller when a request fails this validation rule.
 /// </param>
-[AttributeUsage(AttributeTargets.Property, AllowMultiple = true)]
+[AttributeUsage(AttributeTargets.Property | AttributeTargets.Class, AllowMultiple = true)]
 public sealed class ValidationRuleAttribute(
     string rule,
     string? fieldPath = null,

src/KubeOps.Transpiler/Crds.cs

@@ -111,6 +111,8 @@ public static V1CustomResourceDefinition Transpile(this MetadataLoadContext cont
                     { Count: > 0 } list => list,
                     _ => null,
                 },
+                XKubernetesValidations = context.MapValidationRules(
+                    type.GetCustomAttributesData<ValidationRuleAttribute>()),
             },
         };
 
@@ -309,18 +311,12 @@ private static V1JSONSchemaProps Map(this MetadataLoadContext context, PropertyI
             props.Properties = null;
         }
 
-        if (prop.GetCustomAttributesData<ValidationRuleAttribute>().ToArray() is { Length: > 0 } validations)
+        var propValidations = context.MapValidationRules(prop.GetCustomAttributesData<ValidationRuleAttribute>());
+        if (propValidations != null)
         {
-            props.XKubernetesValidations = validations
-                .Select(validation => new V1ValidationRule
-                {
-                    Rule = validation.GetCustomAttributeCtorArg<string>(context, 0),
-                    FieldPath = validation.GetCustomAttributeCtorArg<string?>(context, 1),
-                    Message = validation.GetCustomAttributeCtorArg<string?>(context, 2),
-                    MessageExpression = validation.GetCustomAttributeCtorArg<string?>(context, 3),
-                    Reason = validation.GetCustomAttributeCtorArg<string?>(context, 4),
-                })
-                .ToList();
+            props.XKubernetesValidations = props.XKubernetesValidations is { } existing
+                ? [.. existing, .. propValidations]
+                : propValidations;
         }
 
         return props;
@@ -411,6 +407,24 @@ static Type GetRootBaseType(Type type)
         };
     }
 
+    private static List<V1ValidationRule>? MapValidationRules(
+        this MetadataLoadContext context,
+        IEnumerable<CustomAttributeData> attributesData)
+    {
+        var rules = attributesData
+            .Select(v => new V1ValidationRule
+            {
+                Rule = v.GetCustomAttributeCtorArg<string>(context, 0),
+                FieldPath = v.GetCustomAttributeCtorArg<string?>(context, 1),
+                Message = v.GetCustomAttributeCtorArg<string?>(context, 2),
+                MessageExpression = v.GetCustomAttributeCtorArg<string?>(context, 3),
+                Reason = v.GetCustomAttributeCtorArg<string?>(context, 4),
+            })
+            .ToList();
+
+        return rules.Count > 0 ? rules : null;
+    }
+
     private static IList<object> GetEnumNames(this MetadataLoadContext context, Type type)
     {
 #if NET9_0_OR_GREATER
@@ -484,6 +498,8 @@ private static V1JSONSchemaProps MapObjectType(this MetadataLoadContext context,
                     },
                     XKubernetesPreserveUnknownFields =
                         type.GetCustomAttributeData<PreserveUnknownFieldsAttribute>() != null ? true : null,
+                    XKubernetesValidations = context.MapValidationRules(
+                        type.GetCustomAttributesData<ValidationRuleAttribute>()),
                 };
         }
     }

test/KubeOps.Transpiler.Test/Crds.Mlc.ValidationRule.Test.cs

@@ -64,6 +64,53 @@ public void Should_Omit_Validations()
         specProperties.XKubernetesValidations.Should().BeNull();
     }
 
+    [Fact]
+    public void Should_Set_Validations_On_Root_Class()
+    {
+        var crd = _mlc.Transpile(typeof(RootClassValidateAttrEntity));
+
+        var schema = crd.Spec.Versions[0].Schema.OpenAPIV3Schema;
+        schema.XKubernetesValidations.Should().HaveCount(1);
+        schema.XKubernetesValidations[0].Rule.Should().Be(Rule1);
+        schema.XKubernetesValidations[0].Message.Should().Be(Message1);
+        schema.XKubernetesValidations[0].MessageExpression.Should().BeNull();
+        schema.XKubernetesValidations[0].FieldPath.Should().BeNull();
+        schema.XKubernetesValidations[0].Reason.Should().BeNull();
+    }
+
+    [Fact]
+    public void Should_Set_Multiple_Validations_On_Root_Class()
+    {
+        var crd = _mlc.Transpile(typeof(MultiRootClassValidateAttrEntity));
+
+        var schema = crd.Spec.Versions[0].Schema.OpenAPIV3Schema;
+        schema.XKubernetesValidations.Should().HaveCount(2);
+        schema.XKubernetesValidations[0].Rule.Should().Be(Rule1);
+        schema.XKubernetesValidations[1].Rule.Should().Be(Rule2);
+    }
+
+    [Fact]
+    public void Should_Set_Validations_On_Nested_Class()
+    {
+        var crd = _mlc.Transpile(typeof(NestedClassValidateAttrEntity));
+
+        var nestedSchema = crd.Spec.Versions[0].Schema.OpenAPIV3Schema.Properties["nested"];
+        nestedSchema.XKubernetesValidations.Should().HaveCount(1);
+        nestedSchema.XKubernetesValidations[0].Rule.Should().Be(Rule1);
+        nestedSchema.XKubernetesValidations[0].Message.Should().Be(Message1);
+    }
+
+    [Fact]
+    public void Should_Merge_Class_And_Property_Validations()
+    {
+        var crd = _mlc.Transpile(typeof(ClassAndPropertyValidateAttrEntity));
+
+        var nestedSchema = crd.Spec.Versions[0].Schema.OpenAPIV3Schema.Properties["nested"];
+        nestedSchema.XKubernetesValidations.Should().HaveCount(2);
+        nestedSchema.XKubernetesValidations[0].Rule.Should().Be(Rule1);
+        nestedSchema.XKubernetesValidations[1].Rule.Should().Be(Rule2);
+    }
+
     [Fact]
     public void Should_Set_ValidationFields()
     {
@@ -86,6 +133,46 @@ public sealed class NoValidateAttrEntity : CustomKubernetesEntity
         public string Property { get; set; } = null!;
     }
 
+    [KubernetesEntity(Group = "testing.dev", ApiVersion = "v1", Kind = "TestEntity")]
+    [ValidationRule(Rule1, message: Message1)]
+    public sealed class RootClassValidateAttrEntity : CustomKubernetesEntity
+    {
+        public string Property { get; set; } = null!;
+    }
+
+    [KubernetesEntity(Group = "testing.dev", ApiVersion = "v1", Kind = "TestEntity")]
+    [ValidationRule(Rule1, message: Message1)]
+    [ValidationRule(Rule2, message: Message2)]
+    public sealed class MultiRootClassValidateAttrEntity : CustomKubernetesEntity
+    {
+        public string Property { get; set; } = null!;
+    }
+
+    [KubernetesEntity(Group = "testing.dev", ApiVersion = "v1", Kind = "TestEntity")]
+    public sealed class NestedClassValidateAttrEntity : CustomKubernetesEntity
+    {
+        public NestedObject Nested { get; set; } = new();
+
+        [ValidationRule(Rule1, message: Message1)]
+        public sealed class NestedObject
+        {
+            public string Name { get; set; } = null!;
+        }
+    }
+
+    [KubernetesEntity(Group = "testing.dev", ApiVersion = "v1", Kind = "TestEntity")]
+    public sealed class ClassAndPropertyValidateAttrEntity : CustomKubernetesEntity
+    {
+        [ValidationRule(Rule2, message: Message2)]
+        public NestedWithClassRule Nested { get; set; } = new();
+
+        [ValidationRule(Rule1, message: Message1)]
+        public sealed class NestedWithClassRule
+        {
+            public string Name { get; set; } = null!;
+        }
+    }
+
     [KubernetesEntity(Group = "testing.dev", ApiVersion = "v1", Kind = "TestEntity")]
     public sealed class SingleValidateAttrEntity : CustomKubernetesEntity
     {