From 175af3da2cc88a53bf343cfc41abe04e591c638c Mon Sep 17 00:00:00 2001
From: Diamond Lewis <findlewis@gmail.com>
Date: Thu, 8 Feb 2018 21:30:41 -0600
Subject: [PATCH] duplicate value on unique index error

---
 spec/schemas.spec.js                          | 24 +++++++++++++++++++
 .../Storage/Mongo/MongoStorageAdapter.js      |  8 ++++++-
 2 files changed, 31 insertions(+), 1 deletion(-)

diff --git a/spec/schemas.spec.js b/spec/schemas.spec.js
index 8f689d7189..ed85d1cc17 100644
--- a/spec/schemas.spec.js
+++ b/spec/schemas.spec.js
@@ -2387,4 +2387,28 @@ describe('schemas', () => {
       });
     });
   });
+
+  it_exclude_dbs(['postgres'])('cannot update to duplicate value on unique index', (done) => {
+    const index = {
+      code: 1
+    };
+    const obj1 = new Parse.Object('UniqueIndexClass');
+    obj1.set('code', 1);
+    const obj2 = new Parse.Object('UniqueIndexClass');
+    obj2.set('code', 2);
+    const adapter = config.database.adapter;
+    adapter._adaptiveCollection('UniqueIndexClass').then(collection => {
+      return collection._ensureSparseUniqueIndexInBackground(index);
+    }).then(() => {
+      return obj1.save();
+    }).then(() => {
+      return obj2.save();
+    }).then(() => {
+      obj1.set('code', 2);
+      return obj1.save();
+    }).then(done.fail).catch((error) => {
+      expect(error.code).toEqual(Parse.Error.DUPLICATE_VALUE);
+      done();
+    });
+  });
 });
diff --git a/src/Adapters/Storage/Mongo/MongoStorageAdapter.js b/src/Adapters/Storage/Mongo/MongoStorageAdapter.js
index 5e21734989..71d37340f9 100644
--- a/src/Adapters/Storage/Mongo/MongoStorageAdapter.js
+++ b/src/Adapters/Storage/Mongo/MongoStorageAdapter.js
@@ -421,7 +421,13 @@ export class MongoStorageAdapter implements StorageAdapter {
     const mongoWhere = transformWhere(className, query, schema);
     return this._adaptiveCollection(className)
       .then(collection => collection._mongoCollection.findAndModify(mongoWhere, [], mongoUpdate, { new: true }))
-      .then(result => mongoObjectToParseObject(className, result.value, schema));
+      .then(result => mongoObjectToParseObject(className, result.value, schema))
+      .catch(error => {
+        if (error.code === 11000) {
+          throw new Parse.Error(Parse.Error.DUPLICATE_VALUE, 'A duplicate value for a field with unique values was provided');
+        }
+        throw error;
+      });
   }
 
   // Hopefully we can get rid of this. It's only used for config and hooks.