CODEWITHSUNDEEP
restbackbone.js
Matt
Matt

Reputation: 2644

Backbone sync request sequence

I've got a Backbone web application that talks to a RESTful PHP server. For PUT and POST it matters in which order the requests arrive at the server and for GET it matters in which order the responses arrive at the client.

The web application does not need to be used concurrently by multiple users, but what might happen is that the user changes its name twice really fast. Then the order in which the server processes PUT /name/Ann and PUT /name/Bea determines whether the name is set to Ann or Bea.

Backbone.Safesync and Backbone.Sync.AjaxQueue are two libraries that try to solve this problem. Doesn't Safesync only solve the problem with GET? Sync.AjaxQueue is outdated, but might serve as inspiration to implement a custom queued sync function. Making sync synchronous would solve the problem. If a request is only sent after the previous response is received, then only one request is processed at a time.

Any advice on how to proceed?

BTW: I don't think using PATCH requests would solve anything, because in my example the same attribute is changed twice.

Upvotes: 0

Views: 220

Answers (2)

Stephen Thomas
Stephen Thomas

Reputation: 14053

If you can afford the delay, an easy approach is to set the async option to false when you call whatever method you're calling that results in the Backbone.sync. For example, in the appropriate model(s) simply override the default sync method to include the additional option.

Upvotes: 1

Creynders
Creynders

Reputation: 4583

There's a few ways to solve this, here's two:

  1. add a timestamp to all requests, store it in the DB as "modified" and let the server check whether the timestamp of the new request is later than the one in the DB in order to be valid

  2. use Promises to delay the second request from being made before the first one is responded on, there's a promise/deferred mechanism built into jquery, but you can also use a 3rd party one, for instance Q or when

Upvotes: 1

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