Using acts_as_api with Rails 5 API only version

When using Rails 5 in the API-only version, your application controller will inherit from ActionController::API instead of the usual ActionController::Base.

When you try to use the render helpers of acts_as_api within the controller, like render_for_api, you might face an error like this:

NoMethodError (undefined method `render_for_api' for #<UsersController:0x007fecd4286fe0>

This is because the helper methods for rendering API responses rely on the ActionController::Base class being loaded. One solution is to include the helper methods in the controller manually. Just add this line to the top of your ApplicationController:

include ActsAsApi::Rendering

And you should be able to use the helper methods again.

More information can be found in this ticket