Ruby on Rails - passing a returned value of a method to has_attached_file. Do I get Ruby syntax wrong?

Ruby on Rails - passing a returned value of a method to has_attached_file. Do I get Ruby syntax wrong?: I'm writ...

The problem is that you're trying to use an instance method picture_sizes_as_strings in a declaration (has_attached_image ) that's run on the class level. It's the difference between calling MyModel.picture_sizes_as_strings and MyModel.first.picture_sizes_as_strings In the first case we are referring to a class method (a method on the class MyModel itself) and in the second case we are referring to an instance method (a method on the individual my_model object.) So first of all you have to change the methods to class methods by prefixing their names with self. , so: def self.picture_sizes { large: {width: 120, height: 150}, small: {width: 60, height: 75} } end Now that doesn't completely fix your problem yet, because has_attached_image is processed when the model is first parsed by ruby. That means it will try to run has_attached_image before you define self.picture_sizes ...

Full article: http://stackoverflow.com/questions/12132991/ruby-on-rails...