From d3c2ca3f293f0f6ebe7eb6d9492ec49c8e1fcc2d Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Martin=20Petlu=C5=A1?= <martinpetlus@gmail.com>
Date: Sat, 18 May 2024 10:03:29 +0200
Subject: [PATCH] fix empty child classes issue (#106)

---
 __tests__/inheritedProperties.test.ts | 49 +++++++++++++++++++++++++--
 src/index.ts                          | 22 +++++++++++-
 2 files changed, 68 insertions(+), 3 deletions(-)

diff --git a/__tests__/inheritedProperties.test.ts b/__tests__/inheritedProperties.test.ts
index b0291ac..9cbd337 100644
--- a/__tests__/inheritedProperties.test.ts
+++ b/__tests__/inheritedProperties.test.ts
@@ -13,7 +13,11 @@ import {
 } from 'class-validator'
 import _get from 'lodash.get'
 
-import { JSONSchema, validationMetadatasToSchemas } from '../src'
+import {
+  JSONSchema,
+  targetConstructorToSchema,
+  validationMetadatasToSchemas,
+} from '../src'
 
 @JSONSchema({
   description: 'Contains email, password and phone',
@@ -43,7 +47,6 @@ class BaseContent {
 @JSONSchema({
   title: 'User object',
 })
-// @ts-ignore: not referenced
 class User extends BaseContent {
   @MinLength(10)
   @MaxLength(20)
@@ -65,6 +68,9 @@ class User extends BaseContent {
   @Contains('hello') welcome: string
 }
 
+// @ts-ignore: not referenced
+class Admin extends User {}
+
 const metadatas = _get(getFromContainer(MetadataStorage), 'validationMetadatas')
 
 describe('Inheriting validation decorators', () => {
@@ -140,4 +146,43 @@ describe('Inheriting validation decorators', () => {
     expect(schemas.BaseContent.required).toEqual(['email', 'phone'])
     expect(schemas.User.required).toEqual(['password', 'email'])
   })
+
+  it('inherits and merges validation decorators from multiple parent classes and empty child class', () => {
+    const schema = targetConstructorToSchema(Admin)
+
+    expect(schema).toEqual({
+      properties: {
+        email: {
+          default: 'some@email.com',
+          format: 'email',
+          type: 'string',
+          not: { type: 'null' },
+        },
+        name: {
+          maxLength: 20,
+          minLength: 10,
+          type: 'string',
+        },
+        password: {
+          description: 'Password field - required!',
+          minLength: 20,
+          type: 'string',
+          not: { type: 'null' },
+        },
+        phone: {
+          format: 'mobile-phone',
+          title: 'Mobile phone number',
+          type: 'string',
+          not: { type: 'null' },
+        },
+        welcome: {
+          pattern: 'hello',
+          type: 'string',
+        },
+      },
+      required: ['name', 'welcome', 'email'],
+      title: 'User object',
+      type: 'object',
+    })
+  })
 })
diff --git a/src/index.ts b/src/index.ts
index 8fdc08d..6ffa99b 100644
--- a/src/index.ts
+++ b/src/index.ts
@@ -100,6 +100,26 @@ export function validationMetadataArrayToSchemas(
   return schemas
 }
 
+/**
+ * Search for the JSON Schema definition from child class up to the
+ * top parent class until empty function name is found.
+ */
+function getTargetConstructorSchema(
+  schemas: Record<string, SchemaObject>,
+  targetConstructor: Function
+): SchemaObject {
+  if (!targetConstructor.name) {
+    return {}
+  } else if (schemas[targetConstructor.name]) {
+    return schemas[targetConstructor.name]
+  } else {
+    return getTargetConstructorSchema(
+      schemas,
+      Object.getPrototypeOf(targetConstructor)
+    )
+  }
+}
+
 /**
  * Generate JSON Schema definitions from the target object constructor.
  */
@@ -122,7 +142,7 @@ export function targetConstructorToSchema(
   metadatas = populateMetadatasWithConstraints(storage, metadatas)
 
   const schemas = validationMetadataArrayToSchemas(metadatas, userOptions)
-  return Object.values(schemas).length ? Object.values(schemas)[0] : {}
+  return getTargetConstructorSchema(schemas, targetConstructor)
 }
 
 /**