sproutcore

Say you have two models: Page, and Item. A Page has many Items. If you try to reconfigure the relationships by setting the 'page' on an Item, the collection of Items on the new owner Page gets notified to update itself, but when it does, it collects the items of the last Page object to be instantiated, whichever that happens to be.

The problem is in record.js#hasMany. Keep in mind that #hasMany gets called just once, when the model (as opposed to individual record objects) is created. #hasMany builds an options/conditions object for the collections, and then returns a function which does the actual creation/lookup of the collection.

The problem is that the scope of the options object is #hasMany, and not the returned function. That means that the same options and conditions objects are used for every single record of that type, the conditions object gets changed as each record is instantiated, and thus every record's collection 'thinks' that it's the very last record of its type to be instantiated, ergo major foulups when it comes time to reload the association. The associations load correctly initially, because they get refreshed right after that particular record has overwritten the conditions object for everyone else.

The solution is to ensure that the scope of the object getting passed to the collection is the function that gets returned by #hasMany, and that's accomplished simply by moving a few lines of code from outside the function into the function.