Convert bson to json before comparing. Fixes #6

lib/index.js

@@ -75,7 +75,7 @@ exports.default = function (schema, opts) {
   // after a document is initialized or saved, fresh snapshots of the
   // documents data are created
   var snapshot = function snapshot() {
-    this._original = this.data();
+    this._original = toJSON(this.data());
   };
   schema.post('init', snapshot);
   schema.post('save', snapshot);
@@ -105,7 +105,7 @@ exports.default = function (schema, opts) {
 
     var ref = this._id;
 
-    var ops = _fastJsonPatch2.default.compare(this.isNew ? {} : this._original, this.data());
+    var ops = _fastJsonPatch2.default.compare(this.isNew ? {} : this._original, toJSON(this.data()));
 
     // don't save a patch when there are no changes to save
     if (!ops.length) {
@@ -170,4 +170,11 @@ var defaultOptions = {
   includes: {},
   removePatches: true,
   transforms: [_humps.pascalize, _humps.decamelize]
+};
+
+// used to convert bson to json - especially ObjectID references need
+// to be converted to hex strings so that the jsonpatch `compare` method
+// works correctly
+var toJSON = function toJSON(obj) {
+  return JSON.parse(JSON.stringify(obj));
 };

src/index.js

@@ -39,6 +39,11 @@ const defaultOptions = {
   transforms: [ pascalize, decamelize ]
 }
 
+// used to convert bson to json - especially ObjectID references need
+// to be converted to hex strings so that the jsonpatch `compare` method
+// works correctly
+const toJSON = (obj) => JSON.parse(JSON.stringify(obj))
+
 export default function (schema, opts) {
   const options = merge({}, defaultOptions, opts)
 
@@ -102,7 +107,7 @@ export default function (schema, opts) {
   // after a document is initialized or saved, fresh snapshots of the
   // documents data are created
   const snapshot = function () {
-    this._original = this.data()
+    this._original = toJSON(this.data())
   }
   schema.post('init', snapshot)
   schema.post('save', snapshot)
@@ -126,7 +131,7 @@ export default function (schema, opts) {
   // added to the associated patch collection
   schema.pre('save', function (next) {
     const { _id: ref } = this
-    const ops = jsonpatch.compare(this.isNew ? {} : this._original, this.data())
+    const ops = jsonpatch.compare(this.isNew ? {} : this._original, toJSON(this.data()))
 
     // don't save a patch when there are no changes to save
     if (!ops.length) {

test/index.js

@@ -223,4 +223,45 @@ describe('mongoose-patch-history', () => {
       ).then(() => done()).catch(done)
     })
   })
+
+  describe('jsonpatch.compare', () => {
+    let Organization
+    let Person
+
+    before(() => {
+      Organization = mongoose.model('Organization', new mongoose.Schema({
+        name: String
+      }))
+
+      const PersonSchema = new mongoose.Schema({
+        name: String,
+        organization: {
+          type: mongoose.Schema.Types.ObjectId,
+          ref: 'Organization'
+        }
+      })
+
+      PersonSchema.plugin(patchHistory, { mongoose, name: 'roomPatches' })
+      Person = mongoose.model('Person', PersonSchema)
+    })
+
+    it('is able to handle ObjectId references correctly', (done) => {
+      Organization.create({ text: 'Home' })
+        .then((o1) => join(o1, Organization.create({ text: 'Work' })))
+        .then(([ o1, o2 ]) => join(o1, o2, Person.create({ name: 'Bob', organization: o1._id })))
+        .then(([ o1, o2, p ]) => join(o1, o2, p.set({ organization: o2._id }).save()))
+        .then(([ o1, o2, p ]) => join(o1, o2, p.patches.find({ ref: p.id })))
+        .then(([ o1, o2, patches ]) => {
+          const pathFilter = (path) => (elem) => elem.path === path
+          const firstOrganizationOperation = patches[0].ops.find(pathFilter('/organization'))
+          const secondOrganizationOperation = patches[1].ops.find(pathFilter('/organization'))
+          assert.equal(patches.length, 2)
+          assert(firstOrganizationOperation)
+          assert(secondOrganizationOperation)
+          assert.equal(firstOrganizationOperation.value, o1._id.toString())
+          assert.equal(secondOrganizationOperation.value, o2._id.toString())
+        })
+        .then(done).catch(done)
+    })
+  })
 })