Merge pull request #7891 from jyrkive/master

Fix #7889

Author: vkarpov15

lib/types/array.js

@@ -39,9 +39,12 @@ function MongooseArray(values, path, doc) {
   // TODO: replace this with `new CoreMongooseArray().concat()` when we remove
   // support for node 4.x and 5.x, see https://i.imgur.com/UAAHk4S.png
   const arr = new CoreMongooseArray();
+  arr[arrayAtomicsSymbol] = {};
 
   if (Array.isArray(values)) {
     values.forEach(v => { arr.push(v); });
+
+    arr[arrayAtomicsSymbol] = values[arrayAtomicsSymbol] || {};
   }
 
   const keysMA = Object.keys(MongooseArray.mixin);
@@ -52,7 +55,6 @@ function MongooseArray(values, path, doc) {
 
   arr[arrayPathSymbol] = path;
   arr.validators = [];
-  arr[arrayAtomicsSymbol] = {};
   arr[arraySchemaSymbol] = void 0;
   if (util.inspect.custom) {
     arr[util.inspect.custom] = arr.inspect;

test/document.populate.test.js

@@ -567,6 +567,44 @@ describe('document.populate', function() {
     });
   });
 
+  describe('gh-7889', function() {
+    it('should save item added to array after populating the array', function(done) {
+      const Car = db.model('gh-7889-1', {
+        model: Number
+      });
+
+      const Player = db.model('gh-7889-2', {
+        cars: [{ type: Schema.Types.ObjectId, ref: 'gh-7889-1' }]
+      });
+
+      let player;
+
+      Car.create({ model: 0 }).then(car => {
+        return Player.create({ cars: [car._id] });
+      }).then(() => {
+        return Player.findOne({});
+      }).then(p => {
+        player = p;
+        return player.populate('cars').execPopulate();
+      }).then(() => {
+        return Car.create({ model: 1 });
+      }).then(car => {
+        player.cars.push(car);
+        return player.populate('cars').execPopulate();
+      }).then(() => {
+        return Car.create({ model: 2 });
+      }).then(car => {
+        player.cars.push(car);
+        return player.save();
+      }).then(() => {
+        return Player.findOne({});
+      }).then(player => {
+        assert.equal(player.cars.length, 3);
+        done();
+      });
+    });
+  });
+
   describe('depopulate', function() {
     it('can depopulate specific path (gh-2509)', function(done) {
       const Person = db.model('gh2509_1', {