fix($resource): return result from prototype methods

[gorkunov]

1. Resource[name] returns value that contains $then and other useful things. #L476
2. Resource.prototype['$' + name] invokes Resource[name] at the end but returns nothing. #L502

Possible fix: add return state to the end of the Resource.prototype['$' + name] definition.

[petebacondarwin]

@gorkunov - Thanks for this PR. Did you realise that in the case of the $... methods you are actually calling them on an instance so the return value that you want is actually the object on which you called the method. After your commit then you would have this situation...

var returnObj = myObj.$save(..);
assert(returnObj === myObj);

In other words, you do have access to this object, it is the original object you called the method on. That being said, it seems like a good idea to be able to chain $then calls easily...

myObject.$get().$then(function() {
  // do stuff to my object, then save
  return myObjec.$save();
}).$then(function() {
  // do stuff once it has saved
});

[petebacondarwin]

In order to merge this feature, can you ensure the following are completed:

• Contributor signed CLA now or in the past (if you just signed, leave a comment here with your real name for cross reference)
• Feature improves existing core functionality
• API is compatible with existing Angular apis and relevant standards (if applicable)
• PR doesn't contain a breaking change
• PR contains unit tests
• PR contains e2e tests (if suitable)
• PR contains documentation update
• PR passes all tests on Travis (sanity)
• PR passes all tests on ci.angularjs.org (cross-browser compatibility)
• PR is rebased against recent master
• PR is squashed into one commit per logical change
• PR's commit messages are descriptive and allows us to autogenerate release notes (required commit message format)
• All changes requested in review have been implemented

[gorkunov]

You mean that it shouldn't provide access for an object and only provide access for a promises?

I also found that $resource uses special shim for then and and returns it as $then like a system/special property of the model. So the second call of then should be without $ and looks strange.

[petebacondarwin]

My second example is what you would get if all the $... instance methods effectively returned this each time, which is what your patch would do.
I quite like the idea of getting the instance methods to return the promise...

[gorkunov]

So maybe change the end of the Resource.prototype['$' + name] definition from:

 var data = hasBody ? this : undefined;
 Resource[name].call(this, params, data, success, error);

to:

  var data = hasBody ? this : undefined,
      value = Resource[name].call(this, params, data, success, error);
  return { then: value.$then };

So we return only promise and can do chaining.

[petebacondarwin]

I guess something like that but it would be nice if we could simply get access to the original promise.

[jonbcard]

Just a heads up that this same change is also already in #2060

[petebacondarwin]

@jonbcard - only just looked at that PR. Yes, let's close this one in favour of the solution being developed in #2060.