From 400bfb9c845de3c801101dbc2eb195ffb7a808ac Mon Sep 17 00:00:00 2001
From: Oskar Dudycz <oskar.dudycz@gmail.com>
Date: Sun, 27 Oct 2024 18:39:54 +0100
Subject: [PATCH] Added deep equals to object comparison in handle method to
 support correctly mutable entities

---
 .../src/core/collection/pongoCollection.ts    |  3 +-
 src/packages/pongo/src/core/index.ts          |  1 +
 .../pongo/src/core/utils/deepEquals.ts        | 56 +++++++++++++++++++
 src/packages/pongo/src/core/utils/index.ts    |  1 +
 .../pongo/src/e2e/postgres.e2e.spec.ts        | 37 ++++++++++++
 5 files changed, 97 insertions(+), 1 deletion(-)
 create mode 100644 src/packages/pongo/src/core/utils/deepEquals.ts
 create mode 100644 src/packages/pongo/src/core/utils/index.ts

diff --git a/src/packages/pongo/src/core/collection/pongoCollection.ts b/src/packages/pongo/src/core/collection/pongoCollection.ts
index 4a48bbf..8873123 100644
--- a/src/packages/pongo/src/core/collection/pongoCollection.ts
+++ b/src/packages/pongo/src/core/collection/pongoCollection.ts
@@ -14,6 +14,7 @@ import {
 } from '@event-driven-io/dumbo';
 import { v7 as uuid } from 'uuid';
 import {
+  deepEquals,
   expectedVersionValue,
   operationResult,
   type CollectionOperationOptions,
@@ -370,7 +371,7 @@ export const pongoCollection = <
 
       const result = await handle(existing as T);
 
-      if (existing === result)
+      if (deepEquals(existing as T, result))
         return operationResult<PongoHandleResult<T>>(
           {
             successful: true,
diff --git a/src/packages/pongo/src/core/index.ts b/src/packages/pongo/src/core/index.ts
index a5475b6..7009e43 100644
--- a/src/packages/pongo/src/core/index.ts
+++ b/src/packages/pongo/src/core/index.ts
@@ -6,3 +6,4 @@ export * from './pongoSession';
 export * from './pongoTransaction';
 export * from './schema';
 export * from './typing';
+export * from './utils';
diff --git a/src/packages/pongo/src/core/utils/deepEquals.ts b/src/packages/pongo/src/core/utils/deepEquals.ts
new file mode 100644
index 0000000..f0c513e
--- /dev/null
+++ b/src/packages/pongo/src/core/utils/deepEquals.ts
@@ -0,0 +1,56 @@
+export const deepEquals = <T>(left: T, right: T): boolean => {
+  if (isEquatable(left)) {
+    return left.equals(right);
+  }
+
+  if (Array.isArray(left)) {
+    return (
+      Array.isArray(right) &&
+      left.length === right.length &&
+      left.every((val, index) => deepEquals(val, right[index]))
+    );
+  }
+
+  if (
+    typeof left !== 'object' ||
+    typeof right !== 'object' ||
+    left === null ||
+    right === null
+  ) {
+    return left === right;
+  }
+
+  if (Array.isArray(right)) return false;
+
+  const keys1 = Object.keys(left);
+  const keys2 = Object.keys(right);
+
+  if (
+    keys1.length !== keys2.length ||
+    !keys1.every((key) => keys2.includes(key))
+  )
+    return false;
+
+  for (const key in left) {
+    if (left[key] instanceof Function && right[key] instanceof Function)
+      continue;
+
+    const isEqual = deepEquals(left[key], right[key]);
+    if (!isEqual) {
+      return false;
+    }
+  }
+
+  return true;
+};
+
+export type Equatable<T> = { equals: (right: T) => boolean } & T;
+
+export const isEquatable = <T>(left: T): left is Equatable<T> => {
+  return (
+    left &&
+    typeof left === 'object' &&
+    'equals' in left &&
+    typeof left['equals'] === 'function'
+  );
+};
diff --git a/src/packages/pongo/src/core/utils/index.ts b/src/packages/pongo/src/core/utils/index.ts
new file mode 100644
index 0000000..f8de580
--- /dev/null
+++ b/src/packages/pongo/src/core/utils/index.ts
@@ -0,0 +1 @@
+export * from './deepEquals';
diff --git a/src/packages/pongo/src/e2e/postgres.e2e.spec.ts b/src/packages/pongo/src/e2e/postgres.e2e.spec.ts
index 821dbaa..bdff085 100644
--- a/src/packages/pongo/src/e2e/postgres.e2e.spec.ts
+++ b/src/packages/pongo/src/e2e/postgres.e2e.spec.ts
@@ -1177,6 +1177,43 @@ void describe('MongoDB Compatibility Tests', () => {
     });
   });
 
+  void it('should make the change if the handler returns the existing document changed', async () => {
+    const pongoCollection = pongoDb.collection<User>('handleCollection');
+
+    const existingDoc: User = { name: 'John', age: 25 };
+
+    const pongoInsertResult = await pongoCollection.insertOne(existingDoc);
+
+    const handle = (existing: User | null) => {
+      if (existing) existing.name = 'New';
+      return existing;
+    };
+
+    const resultPongo = await pongoCollection.handle(
+      pongoInsertResult.insertedId!,
+      handle,
+    );
+
+    assert(resultPongo.successful);
+    assert.deepStrictEqual(resultPongo.document, {
+      ...existingDoc,
+      _id: pongoInsertResult.insertedId,
+      name: 'New',
+      _version: 2n,
+    });
+
+    const pongoDoc = await pongoCollection.findOne({
+      _id: pongoInsertResult.insertedId!,
+    });
+
+    assert.deepStrictEqual(pongoDoc, {
+      ...existingDoc,
+      _id: pongoInsertResult.insertedId,
+      name: 'New',
+      _version: 2n,
+    });
+  });
+
   void describe('No filter', () => {
     void it('should filter and count without filter specified', async () => {
       const pongoCollection = pongoDb.collection<User>('nofilter');