Save with wait:true, patch: true and custom serialize() method

ampersand-model.js

@@ -5,6 +5,10 @@ var assign = require('lodash.assign');
 var isObject = require('lodash.isobject');
 var clone = require('lodash.clone');
 var result = require('lodash.result');
+var transform = require('lodash.transform');
+var keys = require('lodash.keys');
+var intersection = require('lodash.intersection');
+var reduce = require('lodash.reduce');
 
 // Throw an error when a URL is needed, and none is supplied.
 var urlError = function () {
@@ -20,6 +24,31 @@ var wrapError = function (model, options) {
     };
 };
 
+// recursive function to find the attrs in the serialized object
+var transformForPatch = function transformForPatch(obj, attrs) {
+
+    var attrKeys = keys(attrs);
+
+    if (!isObject(obj)) {
+        return obj;
+    }
+
+    // If all attributes are within the object
+    if (intersection(keys(obj), attrKeys).length === attrKeys.length) {
+        // return the subset of passed-in attrs
+        return reduce(attrKeys, function(redux, attrKey) {
+            redux[attrKey] = attrs[attrKey];
+            return redux;
+        }, {});
+    }
+
+    return transform(obj, function(result, val, key) {
+        // run transformForPatch on the next level
+        result[key] = transformForPatch(val, attrs);
+    });
+};
+
+
 var Model = State.extend({
     save: function (key, val, options) {
         var attrs, method;
@@ -60,10 +89,18 @@ var Model = State.extend({
         wrapError(this, options);
 
         method = this.isNew() ? 'create' : (options.patch ? 'patch' : 'update');
-        if (method === 'patch') options.attrs = attrs;
+
+        if (method === 'patch') {
+            options.attrs = transformForPatch(this.serialize(), attrs);
+        }
         // if we're waiting we haven't actually set our attributes yet so
         // we need to do make sure we send right data
-        if (options.wait && method !== 'patch') options.attrs = assign(model.serialize(), attrs);
+        if (options.wait && method !== 'patch') {
+            var clonedModel = new this.constructor(this.getAttributes({props: true}));
+            clonedModel.set(attrs);
+
+            options.attrs = clonedModel.serialize();
+        }
         var sync = this.sync(method, this, options);
 
         // Make the request available on the options object so it can be accessed

package.json

@@ -15,8 +15,12 @@
     "ampersand-version": "^1.0.2",
     "lodash.assign": "^3.2.0",
     "lodash.clone": "^3.0.3",
+    "lodash.intersection": "^3.2.0",
     "lodash.isobject": "^3.0.2",
-    "lodash.result": "^3.1.2"
+    "lodash.keys": "^3.1.2",
+    "lodash.reduce": "^3.1.2",
+    "lodash.result": "^3.1.2",
+    "lodash.transform": "^3.0.4"
   },
   "devDependencies": {
     "browserify": "^8.1.0",

test/backbone.js

@@ -870,6 +870,21 @@ var Backbone = {
         t.equal(env.syncArgs.options.attrs.a, undefined);
     });
 
+    test("save with PATCH and `wait` with a custom serialize method only sends specified attributes in custom format", function (t) {
+        t.plan(4);
+        var Model = Backbone.Model.extend({
+            id: 1,
+            serialize: function() {return {data: {attributes: this.getAttributes({props: true}, true)}};}
+        });
+        var model = new Model({parent_id: 1});
+        model.set({a: 1, b: 2, d: 4, e: 5});
+        model.save({b: 2, d: 4}, {patch: true, wait: true });
+        t.equal(env.syncArgs.method, 'patch');
+        t.equal(_.size(env.syncArgs.options.attrs.data.attributes), 2);
+        t.equal(env.syncArgs.options.attrs.data.attributes.d, 4);
+        t.equal(env.syncArgs.options.attrs.data.attributes.a, undefined);
+    });
+
     test.skip("save doesn't validate twice", function (t) {
         t.plan(1);
         var model = new Backbone.Model();