Avoid exceptions when encountering unsaved objects in dirty mutable containers

Author: andrewimm

src/ParseObject.js

@@ -225,9 +225,15 @@ export default class ParseObject {
       ) {
         // Due to the way browsers construct maps, the key order will not change
         // unless the object is changed
-        var json = encode(val, false, true);
-        var stringified = JSON.stringify(json);
-        if (objectCache[attr] !== stringified) {
+        try {
+          var json = encode(val, false, true);
+          var stringified = JSON.stringify(json);
+          if (objectCache[attr] !== stringified) {
+            dirty[attr] = val;
+          }
+        } catch (e) {
+          // Error occurred, possibly by a nested unsaved pointer in a mutable container
+          // No matter how it happened, it indicates a change in the attribute
           dirty[attr] = val;
         }
       }

src/__tests__/ParseObject-test.js

@@ -1565,6 +1565,36 @@ describe('ObjectController', () => {
     ]);
     xhrs[0].onreadystatechange();
   }));
+
+  it('does not fail when checking if arrays of pointers are dirty', () => {
+    var objectController = CoreManager.getObjectController();
+    var xhrs = [];
+    for (var i = 0; i < 2; i++) {
+      xhrs[i] = {
+        setRequestHeader: jest.genMockFn(),
+        open: jest.genMockFn(),
+        send: jest.genMockFn(),
+        status: 200,
+        readyState: 4
+      };
+    }
+    var current = 0;
+    RESTController._setXHR(function() { return xhrs[current++]; });
+    xhrs[0].responseText = JSON.stringify([{ success: { objectId: 'i333' } }]);
+    xhrs[1].responseText = JSON.stringify({});
+    var brand = ParseObject.fromJSON({
+      className: 'Brand',
+      objectId: 'b123',
+      items: [{ __type: 'Pointer', objectId: 'i222', className: 'Item' }]
+    });
+    expect(brand._getSaveJSON()).toEqual({});
+    var items = brand.get('items');
+    items.push(new ParseObject('Item'));
+    brand.set('items', items);
+    expect(function() { brand.save(); }).not.toThrow();
+
+    xhrs[0].onreadystatechange();
+  });
 });
 
 class MyObject extends ParseObject {