How should server respond to backbone sync

Question

Some newbie questions about backbone.js' save and sync.

1. After calling save/sync functions, what type of response does backbone expect from the server? Is any specific post-processing required after the response is received?

2. How does backbone know whether the model already exists on the server? From the documentation I see that each model has an isNew that checks for whether there is an "id". So "id" is the id from the server, whereas "cid" is what backbone creates for each model. Correct? If so, what are the general steps for the server to inform backbone what the id of a model is, when:

   a) the model is first created and synced,

   b) subsequently when the model is fetched,

   c) or when the model is populated on page load?

Thanks for help.

Answer 1

Answers to your questions:

1. When you get a response back from the server, the response data goes through the parse method. For models, the parse method must respond with an attributes hash which will be used in a 'set' call to the model. For collections, the parse method must respond with an array of attributes hashes representative of the models to be maintained by the collection. In each case, there are default implementations which use the raw response object. If your response does not return usable hashes, then you need to provide your own parse method which does what you want.

2. You are correct on your statement about how isNew works. Your server response must provide some sort of id that you either use or transform into an id attribute on the model in the parse method. The transform would be required if your server response does not call the object id as an attribute called 'id'. I think your entire second question hinges on your proper understanding of the parse method. This method must return an attributes hash which includes also the 'id' attribute.