model.save only updates changed data

added deep-diff dependency

lib/model.js

@@ -2,6 +2,7 @@
 Model = function(collectionName, obj, options) {
   options = options || {};
   this.attributes = obj;
+  this.syncSavedState();
 
   this._collection = Graviton._collections[collectionName];
 
@@ -80,11 +81,29 @@ Model.prototype.persist = function() {
   return false;
 };
 
+Model.prototype.syncSavedState = function() {
+  // create a deep clone. is there a better way to do this?
+  this._savedState = JSON.stringify(this.attributes);
+};
+
+Model.prototype.savedState = function() {
+  // only parse the saved state when needed for efficiency
+  if (_.isString(this._savedState)) this._savedState = JSON.parse(this._savedState);
+  return this._savedState;
+};
+
 // insert or update
 // TODO: track the attributes that have changed and only update those
 Model.prototype.save = function() {
   if (!this.persist()) {
-    this._collection.update(this._id, {$set: _.omit(this.attributes, '_id')});
+    var diff = Graviton.mongoDiff(this.savedState(), this.attributes);
+    if (!_.isEmpty(diff.operators)) {
+      this._collection.update(this._id, diff.operators);
+      this.syncSavedState();
+      return {updated: true, warnings: diff.warnings};
+    }
+    return false;
   }
-  return this;
+  this.syncSavedState();
+  return {inserted: true};
 };

lib/mongo-diff.js

@@ -0,0 +1,39 @@
+var MongoDiff = function(lhs, rhs, prefilter) {
+  this._lhs = lhs;
+  this._rhs = rhs;
+  this._deepDiffs = DeepDiff.diff(lhs, rhs, prefilter);
+  this.operators = {};
+  this.warnings = [];
+  for (var i in this._deepDiffs) {
+    this.addDeepDiff(this._deepDiffs[i]);
+  }
+};
+
+MongoDiff.prototype.addOperator = function(operator, path, val) {
+  var obj = this.operators[operator] = this.operators[operator] || {};
+  obj[path] = val;
+};
+
+MongoDiff.prototype.addDeepDiff = function(diff) {
+  var path = diff.path.join('.');
+  switch (diff.kind) {
+  case 'A':
+    var set = this.operators.$set;
+    if (!(set && set[path])) {
+      this.addOperator("$set", path, Graviton.getProperty(this._rhs, path));
+      this.warnings.push("Will replace entire array at: '"+path+"'. Individual updates should probably be done manually instead.");
+    }
+    break;
+  case 'E':
+  case 'N':
+    this.addOperator("$set", path, diff.rhs);
+    break;
+  case 'D':
+    this.addOperator("$unset", path, "");
+    break;
+  }
+};
+
+Graviton.mongoDiff = function(lhs, rhs, prefilter) {
+  return new MongoDiff(lhs, rhs, prefilter);
+};

package.js

@@ -4,18 +4,18 @@ Package.describe({
 
 Package.on_use(function (api, where) {
   api.use(["underscore"], ["client", "server"]);
-  api.add_files(['lib/model.js', 'lib/relations.js', 'graviton.js'], ['client', 'server']);
+  api.use(['deep-diff'], ['client', 'server']);
+  api.add_files(['lib/model.js', 'lib/relations.js', 'graviton.js', 'lib/mongo-diff.js'], ['client', 'server']);
 
   if (typeof api.export !== 'undefined') {
-    // api.export("Model", ["client", "server"]);
     api.export("Graviton", ["client", "server"]);
   }
 });
 
 Package.on_test(function (api) {
   api.use(['graviton', 'tinytest', 'test-helpers']);
 
-  api.add_files('test/graviton-test.js', ['client', 'server']);
+  api.add_files(['test/graviton-test.js', 'test/mongo-diff-test.js'], ['client', 'server']);
 });
 
 

smart.json

@@ -5,5 +5,7 @@
   "author": "Jeremy Dunn",
   "version": "0.0.2",
   "git": "https://github.com/fractallian/graviton.git",
-  "packages": {}
+  "packages": {
+    "deep-diff": "0.0.1"
+  }
 }

test/mongo-diff-test.js

@@ -0,0 +1,38 @@
+var lhs = {
+  name: 'my object',
+  description: 'it\'s an object!',
+  details: {
+    it: 'has',
+    an: 'array',
+    with: ['a', 'few', 'elements'],
+    array: ['inside', {another: ['array']}]
+  }
+};
+
+var rhs = {
+  name: 'updated object',
+  description: 'it\'s an object!',
+  details: {
+    it: 'has',
+    an: 'array',
+    with: ['a', 'few', 'more', 'elements', { than: 'before' }],
+    array: ['inside', {another: ['array', 'should not be tested']}]
+  }
+};
+
+
+var expected = {
+  $set: {
+    name: 'updated object',
+    'details.with': ['a', 'few', 'more', 'elements', { than: 'before' }],
+    'details.array': ['inside', {another: ['array', 'should not be tested']}]
+  }
+};
+
+var mongoDiff = Graviton.mongoDiff(lhs, rhs);
+
+
+Tinytest.add('mongo diff', function(test) {
+  test.isTrue(_.isEqual(mongoDiff.operators, expected));
+  test.equal(mongoDiff.warnings.length, 2);
+});