I just need to use the res.render function at some places but it is not passed to the callback I am using. Isn't there somewhere a global version of the render function or is there another way to access this?
In Sails v0.10.4 there is
sails.renderView(viewPath, options, callback);
Also, when rendering emails, you probably don't need to use a layout. So before calling
options.layout = false;
You don't need it at all places, really.
res is a response object and it makes sense only in controllers, because only controllers deal with request handling and response rendering.
Do you want to use
res.render from models, services? Maybe it's because you think that all your code is always in we_have_request_and_user_is_waiting_for_response state.
Well, It's not true: model methods and services can be called from sails console, or from background workers, or from code, than runs by schedule. In these cases we don't have
res object at all.
Controllers are place specially designed to contain user actions responding logic. So, you should place that logic in controllers. MVC