From e25dafc296d9930b17c52d3fc6d33590e29a1de9 Mon Sep 17 00:00:00 2001
From: Valeri Karpov <val@karpov.io>
Date: Tue, 17 Dec 2024 10:03:44 -0500
Subject: [PATCH] fix(schema): avoid throwing duplicate index error if index
 spec keys have different order or index has a custom name

Fix #15109
---
 lib/helpers/indexes/isIndexSpecEqual.js  | 32 ++++++++++++++++++++++++
 lib/schema.js                            |  6 ++---
 test/helpers/indexes.isIndexSpecEqual.js | 27 ++++++++++++++++++++
 test/schema.test.js                      |  9 +++++++
 4 files changed, 71 insertions(+), 3 deletions(-)
 create mode 100644 lib/helpers/indexes/isIndexSpecEqual.js
 create mode 100644 test/helpers/indexes.isIndexSpecEqual.js

diff --git a/lib/helpers/indexes/isIndexSpecEqual.js b/lib/helpers/indexes/isIndexSpecEqual.js
new file mode 100644
index 0000000000..f26ed34efd
--- /dev/null
+++ b/lib/helpers/indexes/isIndexSpecEqual.js
@@ -0,0 +1,32 @@
+'use strict';
+
+/**
+ * Compares two index specifications to determine if they are equal.
+ *
+ * #### Example:
+ *     isIndexSpecEqual({ a: 1, b: 1 }, { a: 1, b: 1 }); // true
+ *     isIndexSpecEqual({ a: 1, b: 1 }, { b: 1, a: 1 }); // false
+ *     isIndexSpecEqual({ a: 1, b: -1 }, { a: 1, b: 1 }); // false
+ *
+ * @param {Object} spec1 - The first index specification to compare.
+ * @param {Object} spec2 - The second index specification to compare.
+ * @returns {Boolean} Returns true if the index specifications are equal, otherwise returns false.
+ */
+
+module.exports = function isIndexSpecEqual(spec1, spec2) {
+  const spec1Keys = Object.keys(spec1);
+  const spec2Keys = Object.keys(spec2);
+
+  if (spec1Keys.length !== spec2Keys.length) {
+    return false;
+  }
+
+  for (let i = 0; i < spec1Keys.length; i++) {
+    const key = spec1Keys[i];
+    if (key !== spec2Keys[i] || spec1[key] !== spec2[key]) {
+      return false;
+    }
+  }
+
+  return true;
+};
diff --git a/lib/schema.js b/lib/schema.js
index 2915bf5f5a..ddde465929 100644
--- a/lib/schema.js
+++ b/lib/schema.js
@@ -18,13 +18,13 @@ const getConstructorName = require('./helpers/getConstructorName');
 const getIndexes = require('./helpers/schema/getIndexes');
 const handleReadPreferenceAliases = require('./helpers/query/handleReadPreferenceAliases');
 const idGetter = require('./helpers/schema/idGetter');
+const isIndexSpecEqual = require('./helpers/indexes/isIndexSpecEqual');
 const merge = require('./helpers/schema/merge');
 const mpath = require('mpath');
 const setPopulatedVirtualValue = require('./helpers/populate/setPopulatedVirtualValue');
 const setupTimestamps = require('./helpers/timestamps/setupTimestamps');
 const utils = require('./utils');
 const validateRef = require('./helpers/populate/validateRef');
-const util = require('util');
 
 const hasNumericSubpathRegex = /\.\d+(\.|$)/;
 
@@ -899,7 +899,7 @@ Schema.prototype.removeIndex = function removeIndex(index) {
 
   if (typeof index === 'object') {
     for (let i = this._indexes.length - 1; i >= 0; --i) {
-      if (util.isDeepStrictEqual(this._indexes[i][0], index)) {
+      if (isIndexSpecEqual(this._indexes[i][0], index)) {
         this._indexes.splice(i, 1);
       }
     }
@@ -2147,7 +2147,7 @@ Schema.prototype.index = function(fields, options) {
   }
 
   for (const existingIndex of this.indexes()) {
-    if (util.isDeepStrictEqual(existingIndex[0], fields)) {
+    if (options.name == null && existingIndex[1].name == null && isIndexSpecEqual(existingIndex[0], fields)) {
       throw new MongooseError(`Schema already has an index on ${JSON.stringify(fields)}`);
     }
   }
diff --git a/test/helpers/indexes.isIndexSpecEqual.js b/test/helpers/indexes.isIndexSpecEqual.js
new file mode 100644
index 0000000000..0995836ddb
--- /dev/null
+++ b/test/helpers/indexes.isIndexSpecEqual.js
@@ -0,0 +1,27 @@
+'use strict';
+
+const assert = require('assert');
+const isIndexSpecEqual = require('../../lib/helpers/indexes/isIndexSpecEqual');
+
+describe('isIndexSpecEqual', function() {
+  it('should return true for equal index specifications', () => {
+    const spec1 = { name: 1, age: -1 };
+    const spec2 = { name: 1, age: -1 };
+    const result = isIndexSpecEqual(spec1, spec2);
+    assert.strictEqual(result, true);
+  });
+
+  it('should return false for different key order', () => {
+    const spec1 = { name: 1, age: -1 };
+    const spec2 = { age: -1, name: 1 };
+    const result = isIndexSpecEqual(spec1, spec2);
+    assert.strictEqual(result, false);
+  });
+
+  it('should return false for different index keys', () => {
+    const spec1 = { name: 1, age: -1 };
+    const spec2 = { name: 1, dob: -1 };
+    const result = isIndexSpecEqual(spec1, spec2);
+    assert.strictEqual(result, false);
+  });
+});
diff --git a/test/schema.test.js b/test/schema.test.js
index 6378ec340a..e7c8a720cb 100644
--- a/test/schema.test.js
+++ b/test/schema.test.js
@@ -3294,5 +3294,14 @@ describe('schema', function() {
     assert.throws(() => {
       ObjectKeySchema.index({ key: 1 });
     }, /MongooseError.*already has an index/);
+
+    ObjectKeySchema.index({ key: 1, type: 1 });
+    assert.throws(() => {
+      ObjectKeySchema.index({ key: 1, type: 1 });
+    }, /MongooseError.*already has an index/);
+
+    ObjectKeySchema.index({ type: 1, key: 1 });
+    ObjectKeySchema.index({ key: 1, type: -1 });
+    ObjectKeySchema.index({ key: 1, type: 1 }, { unique: true, name: 'special index' });
   });
 });