zoellner · November 8, 2017 19:01 · Nov 8, 2017 · Nov 8, 2017 · Nov 8, 2017
diff --git a/index.js b/index.js
@@ -1,5 +1,7 @@
 'use strict';
 
+//see https://github.com/Automattic/mongoose/issues/5800
+
 const mongoose = require('mongoose');
 const assert = require('assert');
 

diff --git a/index.js b/index.js
@@ -4,7 +4,7 @@ const mongoose = require('mongoose');
 const assert = require('assert');
 
 mongoose.Promise = global.Promise;
-mongoose.connect('mongodb://localhost/mongoose-bug-hook-set');
+mongoose.connect('mongodb://localhost/mongoose-gh-5800');
 
 const MainSchema = new mongoose.Schema({
   a: {

diff --git a/index.js b/index.js
@@ -0,0 +1,52 @@
+'use strict';
+
+const mongoose = require('mongoose');
+const assert = require('assert');
+
+mongoose.Promise = global.Promise;
+mongoose.connect('mongodb://localhost/mongoose-bug-hook-set');
+
+const MainSchema = new mongoose.Schema({
+  a: {
+    b: {type: String, default: 'some default'},
+    c: {type: Number, default: 0},
+    d: {type: String}
+  },
+  e: {type: String}
+});
+
+MainSchema
+.pre('save', function(next) {
+  if (this.isModified()) {
+    //the expectation would be that only a.c is updated on save, not all of a
+    this.set('a.c', 100, Number);
+  }
+  next();
+});
+
+const Main = mongoose.model('Main', MainSchema);
+
+
+Main.remove({}, (err) => { //reset
+  assert.ifError(err);
+  Main.create({a: {b: 'not the default', d: 'some value'}, e: 'e'}, (err, m1) => { //create new document
+    assert.ifError(err);
+    console.log('m1', m1);
+    assert.equal(m1.a.b, 'not the default');
+    assert.equal(m1.a.d, 'some value');
+    Main.findOne({}).select('e').exec((err, m1select) => { //load with subset of fields
+      assert.ifError(err);
+      m1select.e = 'e modified';
+      m1select.save((err) => {
+        assert.ifError(err);
+        Main.findOne({}).exec((err, m1after) => { //load document again
+          assert.ifError(err);
+          console.log('m1after', m1after); //at this point a.d is missing and a.b is the default value
+          assert.equal(m1after.a.b, 'not the default');
+          assert.equal(m1after.a.d, 'some value');
+          process.exit(0);
+        });
+      });
+    });
+  });
+});