fix: overwrite validation decorators from parent class when defined in child

rdubigny · rdubigny · commit 88f024420827 · 2025-11-07T17:14:46.000+01:00
diff --git a/README.md b/README.md
@@ -371,7 +371,7 @@ export class Post {
 
 ## Inheriting Validation decorators
 
-When you define a subclass which extends from another one, the subclass will automatically inherit the parent's decorators. If a property is redefined in the descendant, class decorators will be applied on it from both its own class and the base class.
+When you define a subclass which extends from another one, the subclass will automatically inherit the parent's decorators. If a property is redefined in the descendant, class decorators will be applied on it from both its own class and the base class. If a property-decorator pair is defined in both the subclass and parent-class, the decorator from the subclass will be used instead of the parent-class. For this purpose, "@IsDefined()" and "@IsOptional()" are considered the same.
 
 ```typescript
 import { validate } from 'class-validator';
@@ -733,6 +733,7 @@ Lets create another custom validation decorator called `IsUserAlreadyExist`:
    export function IsUserAlreadyExist(validationOptions?: ValidationOptions) {
      return function (object: Object, propertyName: string) {
        registerDecorator({
+         name: 'isUserAlreadyExist',
          target: object.constructor,
          propertyName: propertyName,
          options: validationOptions,
diff --git a/src/decorator/common/Allow.ts b/src/decorator/common/Allow.ts
@@ -4,12 +4,15 @@ import { ValidationTypes } from '../../validation/ValidationTypes';
 import { ValidationMetadata } from '../../metadata/ValidationMetadata';
 import { getMetadataStorage } from '../../metadata/MetadataStorage';
 
+export const ALLOW = 'allow';
+
 /**
  * If object has both allowed and not allowed properties a validation error will be thrown.
  */
 export function Allow(validationOptions?: ValidationOptions): PropertyDecorator {
   return function (object: object, propertyName: string): void {
     const args: ValidationMetadataArgs = {
+      name: ALLOW,
       type: ValidationTypes.WHITELIST,
       target: object.constructor,
       propertyName: propertyName,
diff --git a/src/decorator/common/Validate.ts b/src/decorator/common/Validate.ts
@@ -5,6 +5,8 @@ import { getMetadataStorage } from '../../metadata/MetadataStorage';
 import { ValidationTypes } from '../../validation/ValidationTypes';
 import { ConstraintMetadata } from '../../metadata/ConstraintMetadata';
 
+export const VALIDATE = 'validate';
+
 /**
  * Registers custom validator class.
  */
@@ -40,6 +42,7 @@ export function Validate(
 ): PropertyDecorator {
   return function (object: object, propertyName: string): void {
     const args: ValidationMetadataArgs = {
+      name: VALIDATE,
       type: ValidationTypes.CUSTOM_VALIDATION,
       target: object.constructor,
       propertyName: propertyName,
diff --git a/src/decorator/common/ValidateIf.ts b/src/decorator/common/ValidateIf.ts
@@ -4,6 +4,8 @@ import { ValidationTypes } from '../../validation/ValidationTypes';
 import { ValidationMetadata } from '../../metadata/ValidationMetadata';
 import { getMetadataStorage } from '../../metadata/MetadataStorage';
 
+const VALIDATE_IF = 'validateIf';
+
 /**
  * Ignores the other validators on a property when the provided condition function returns false.
  */
@@ -13,6 +15,7 @@ export function ValidateIf(
 ): PropertyDecorator {
   return function (object: object, propertyName: string): void {
     const args: ValidationMetadataArgs = {
+      name: VALIDATE_IF,
       type: ValidationTypes.CONDITIONAL_VALIDATION,
       target: object.constructor,
       propertyName: propertyName,
diff --git a/src/decorator/common/ValidateNested.ts b/src/decorator/common/ValidateNested.ts
@@ -4,6 +4,7 @@ import { ValidationTypes } from '../../validation/ValidationTypes';
 import { ValidationMetadata } from '../../metadata/ValidationMetadata';
 import { getMetadataStorage } from '../../metadata/MetadataStorage';
 
+const VALIDATE_NESTED = 'validateNested';
 /**
  * Objects / object arrays marked with this decorator will also be validated.
  */
@@ -14,6 +15,7 @@ export function ValidateNested(validationOptions?: ValidationOptions): PropertyD
 
   return function (object: object, propertyName: string): void {
     const args: ValidationMetadataArgs = {
+      name: VALIDATE_NESTED,
       type: ValidationTypes.NESTED_VALIDATION,
       target: object.constructor,
       propertyName: propertyName,
diff --git a/src/decorator/common/ValidatePromise.ts b/src/decorator/common/ValidatePromise.ts
@@ -4,12 +4,15 @@ import { ValidationTypes } from '../../validation/ValidationTypes';
 import { ValidationMetadata } from '../../metadata/ValidationMetadata';
 import { getMetadataStorage } from '../../metadata/MetadataStorage';
 
+export const VALIDATE_PROMISE = 'validatePromise';
+
 /**
  * Resolve promise before validation
  */
 export function ValidatePromise(validationOptions?: ValidationOptions): PropertyDecorator {
   return function (object: object, propertyName: string): void {
     const args: ValidationMetadataArgs = {
+      name: VALIDATE_PROMISE,
       type: ValidationTypes.PROMISE_VALIDATION,
       target: object.constructor,
       propertyName: propertyName,
diff --git a/src/metadata/MetadataStorage.ts b/src/metadata/MetadataStorage.ts
@@ -3,6 +3,8 @@ import { ConstraintMetadata } from './ConstraintMetadata';
 import { ValidationSchema } from '../validation-schema/ValidationSchema';
 import { ValidationSchemaToMetadataTransformer } from '../validation-schema/ValidationSchemaToMetadataTransformer';
 import { getGlobal } from '../utils';
+import { IS_DEFINED } from '../decorator/common/IsDefined';
+import { IS_OPTIONAL } from '../decorator/common/IsOptional';
 
 /**
  * Storage all metadatas.
@@ -138,10 +140,13 @@ export class MetadataStorage {
     // filter out duplicate metadatas, prefer original metadatas instead of inherited metadatas
     const uniqueInheritedMetadatas = inheritedMetadatas.filter(inheritedMetadata => {
       return !originalMetadatas.find(originalMetadata => {
-        return (
-          originalMetadata.propertyName === inheritedMetadata.propertyName &&
-          originalMetadata.type === inheritedMetadata.type
-        );
+        const isSameProperty = originalMetadata.propertyName === inheritedMetadata.propertyName;
+        const isSameValidator =
+          originalMetadata.name === inheritedMetadata.name ||
+          (originalMetadata.name === IS_DEFINED && inheritedMetadata.name === IS_OPTIONAL) ||
+          (originalMetadata.name === IS_OPTIONAL && inheritedMetadata.name === IS_DEFINED);
+
+        return isSameProperty && isSameValidator;
       });
     });
 
diff --git a/src/metadata/ValidationMetadata.ts b/src/metadata/ValidationMetadata.ts
@@ -10,14 +10,14 @@ export class ValidationMetadata {
   // -------------------------------------------------------------------------
 
   /**
-   * Validation type.
+   * Validation type. Should be one of the ValidationTypes values.
    */
   type: string;
 
   /**
-   * Validator name.
+   * Validation name. Used to uniquely identify this validator.
    */
-  name?: string;
+  name: string;
 
   /**
    * Target class to which this validation is applied.
diff --git a/src/metadata/ValidationMetadataArgs.ts b/src/metadata/ValidationMetadataArgs.ts
@@ -5,14 +5,14 @@ import { ValidationOptions } from '../decorator/ValidationOptions';
  */
 export interface ValidationMetadataArgs {
   /**
-   * Validation type.
+   * Validation type. Should be one of the ValidationTypes values.
    */
   type: string;
 
   /**
-   * Validator name.
+   * Validation name. Used to uniquely identify this validator.
    */
-  name?: string;
+  name: string;
 
   /**
    * Object that is used to be validated.
diff --git a/src/validation-schema/ValidationSchema.ts b/src/validation-schema/ValidationSchema.ts
@@ -17,14 +17,14 @@ export interface ValidationSchema {
      */
     [propertyName: string]: {
       /**
-       * Validation type. Should be one of the ValidationTypes value.
+       * Validation type. Should be one of the ValidationTypes values.
        */
       type: string;
 
       /**
-       * Validator name.
+       * Validation name. Used to uniquely identify this validator.
        */
-      name?: string;
+      name: string;
 
       /**
        * Constraints set by validation type.
diff --git a/test/functional/inherited-validation.spec.ts b/test/functional/inherited-validation.spec.ts
@@ -1,4 +1,4 @@
-import { Contains, MinLength } from '../../src/decorator/decorators';
+import { Contains, MinLength, Equals, Min, IsOptional, IsDefined } from '../../src/decorator/decorators';
 import { Validator } from '../../src/validation/Validator';
 
 const validator = new Validator();
@@ -34,4 +34,176 @@ describe('inherited validation', () => {
       expect(errors[1].value).toEqual('helo world');
     });
   });
+
+  it('should use validators from parent and child classes', () => {
+    expect.assertions(5);
+
+    class MyClass {
+      @Contains('hello')
+      title: string;
+    }
+
+    class MySubClass extends MyClass {
+      @MinLength(5)
+      title: string;
+    }
+
+    const model = new MySubClass();
+    model.title = 'helo';
+    return validator.validate(model).then(errors => {
+      expect(errors.length).toEqual(1);
+      expect(errors[0].target).toEqual(model);
+      expect(errors[0].property).toEqual('title');
+      expect(errors[0].constraints).toEqual({
+        minLength: 'title must be longer than or equal to 5 characters',
+        contains: 'title must contain a hello string',
+      });
+      expect(errors[0].value).toEqual('helo');
+    });
+  });
+
+  it('should override inherited validators in sub classes', () => {
+    expect.assertions(9);
+
+    class MyClass {
+      @Min(30)
+      age: number;
+
+      @Equals('validator')
+      first_name: string;
+
+      @Equals('class')
+      last_name: string;
+    }
+
+    class MySubClass extends MyClass {
+      @Min(40)
+      age: number;
+
+      @Equals('class')
+      first_name: string;
+
+      @Equals('validator')
+      last_name: string;
+    }
+
+    const model = new MySubClass();
+    model.age = 20; // fail validation (using sub classes constraint)
+    model.first_name = 'class'; // pass validation (overriding fail from parent)
+    model.last_name = 'class'; // fail validation (overriding pass from parent)
+
+    return validator.validate(model).then(errors => {
+      expect(errors.length).toEqual(2);
+      expect(errors[0].target).toEqual(model);
+      expect(errors[0].property).toEqual('age');
+      expect(errors[0].constraints).toEqual({
+        min: 'age must not be less than 40',
+      });
+      expect(errors[0].value).toEqual(20);
+
+      expect(errors[1].target).toEqual(model);
+      expect(errors[1].property).toEqual('last_name');
+      expect(errors[1].constraints).toEqual({
+        equals: 'last_name must be equal to validator',
+      });
+      expect(errors[1].value).toEqual('class');
+    });
+  });
+
+  it('should not override different validators of inherited properties in the parent class', () => {
+    expect.assertions(4);
+
+    class MyClass {
+      @Contains('parent-class')
+      title: string;
+    }
+
+    class MySubClass extends MyClass {
+      @Equals('sub-class')
+      title: string;
+    }
+
+    const model = new MySubClass();
+    model.title = 'sub-class';
+
+    return validator.validate(model).then(errors => {
+      expect(errors.length).toEqual(1);
+      expect(errors[0].target).toEqual(model);
+      expect(errors[0].property).toEqual('title');
+      expect(errors[0].constraints).toEqual({
+        contains: 'title must contain a parent-class string',
+      });
+    });
+  });
+
+  it('should not override different validators of inherited properties in the sub class', () => {
+    expect.assertions(4);
+
+    class MyClass {
+      @Contains('parent-class')
+      title: string;
+    }
+
+    class MySubClass extends MyClass {
+      @Equals('sub-class')
+      title: string;
+    }
+
+    const model = new MySubClass();
+    model.title = 'parent-class';
+
+    return validator.validate(model).then(errors => {
+      expect(errors.length).toEqual(1);
+      expect(errors[0].target).toEqual(model);
+      expect(errors[0].property).toEqual('title');
+      expect(errors[0].constraints).toEqual({
+        equals: 'title must be equal to sub-class',
+      });
+    });
+  });
+
+  it('should override isOptional validator in the parent class', () => {
+    expect.assertions(4);
+
+    class MyClass {
+      @IsOptional()
+      title?: string;
+    }
+
+    class MySubClass extends MyClass {
+      @IsDefined()
+      title: string;
+    }
+
+    const model = new MySubClass();
+
+    return validator.validate(model).then(errors => {
+      expect(errors.length).toEqual(1);
+      expect(errors[0].target).toEqual(model);
+      expect(errors[0].property).toEqual('title');
+      expect(errors[0].constraints).toEqual({
+        isDefined: 'title should not be null or undefined',
+      });
+    });
+  });
+
+  it('should override isDefined validator in the parent class', () => {
+    expect.assertions(1);
+
+    class MyClass {
+      @IsDefined()
+      title?: string;
+    }
+
+    class MySubClass extends MyClass {
+      @IsOptional()
+      title: string;
+    }
+
+    const model = new MySubClass();
+
+    return validator.validate(model).then(errors => {
+      expect(errors.length).toEqual(0);
+    });
+  });
 });
