Question

My back-end has two separate pages, one for handling the model save request and the other for model fetch.

What is the best approach for calling save() and fetch() to use different URLs? Thanks.

Edit:
After studying the annotated source, I see that one can actually supply an options hash to fetch and save

//taken from backbone source:
save : function(attrs, options) {
  options || (options = {});
  if (attrs && !this.set(attrs, options)) return false;
  var model = this;
  var success = options.success;
  options.success = function(resp, status, xhr) {
    if (!model.set(model.parse(resp, xhr), options)) return false;
    if (success) success(model, resp, xhr);
  };
  options.error = wrapError(options.error, model, options);
  var method = this.isNew() ? 'create' : 'update';
  return (this.sync || Backbone.sync).call(this, method, this, options);
},

In the save, what purpose does the attrs serve? I’ve just been calling myModel.save() without passing anything in and it’s always been hashing my model’s attributes correctly. But now that I want to supply a ‘save url’ and I’m tempted to call

myModel.save(undefined, {
    url: 'myPath'
})

with the undefined required to ‘skip’ the first attrs paramter.

Answer 1

If you’re reading the source you probably already have a working solution. You essentially have two options (probably more)-

1. Pass URL in save()/fetch()

save() takes two parameters attr and options
attr – is a hash of model attributes and is used to update the model before save.
eg.

myModel.save(attrs)

is equivalent to

myModel.set(attrs)
myModel.save()

The second parameter is an options hash, which is passed down to this.sync() (and then Backbone.sync and then $.ajax) – setting the url in this hash will work as expected.
You can pass false, undefined, or {} as the first parameter to skip the update.

1. Override Backbone.sync

Rather than have url’s scattered throughout your code every time you call save() or fetch() write your own sync function to compute the url for you, the delegate to the original Backbone.sync to do the heavy lifting

eg. (This sync function adds /save to the url on CREATE, UPDATE and DELETE actions)

function mySyncFunction(method, model, options){
  if(method=='GET'){
    options.url = model.url; 
  }else{
     options.url = model.url + '/save'; 
  }
  return Backbone.sync(method, model, options);
}

To use your custom sync method just declare it as part of your model

var myModel = Backbone.Model.extend({ 
  ...

  "sync": mySyncFunction,

  ...
});