Select Model based on year variable - ruby-on-rails

Question

I am building a new app in Rails for an internal project that changes slightly each year based on the requirements of our clients. Any changes between years will occur within the models (add/remove columns, formatting, reports, etc). My plan is to build it to the requirements for this year and going forward each year I will create a new model and migration (e.g. Sample2019Record, Sample2020Record) that will encapsulate the requirements for that year. The app also needs to render previous year data and all the data is scoped based on the year meaning there is no need to render or query multiple years data. I would prefer not to create a new app each year since that is more apps that need to be maintained.
So my idea is to include the year into the URL (/2018/sample/new or /sample/new?year=2018) and parse the model based on the year ("Sample#{year}Record"). Can rails handle this safely and is there a Gem that can help assist with this approach?
Here is what I came up with, thanks for the advice.
routes.rb
get '/:year/samples', to: 'samples#index', as: :samples, defaults: { year: Time.current.year }
Routes will always default to the current year
application_controller.rb
before_action :check_year
def check_year
if params.has_key?(:year)
if "Sample#{params[:year]}Record".safe_constantize.nil?
redirect_to root_path(year: Time.current.year), notice: "Invalid Year"
end
else
redirect_to root_path(year: Time.current.year), notice: "Invalid Year"
end
end
def get_sample_record(year=Time.current.year)
"Sample#{year}Record".safe_constantize
end
Added a before_action to check the year parameter and added the get_sample_record method to safely constantize the record that can be called from any controller with an optional year like so:
sample_controller.rb
sample_2018_record = get_sample_record
sample_2018_record.count
#> 304
sample_2017_record = get_sample_record 2017
sample_2017_record.count
#> 575683
The result will be nil if an invalid year is passed so I will handle the check in the controller.

Answer 1

As #DaveNewton said, this seems like it should work fine so long as you keep data corresponding to different years' requirements in different tables. A few other observations:
Rails has a helper method constantize for parsing a model from a string:
klass_name = "Sample#{year}Record"
record = klass_name.constantize.new()
will make the variable record an instance of your class corresponding to the year variable. You may find it helpful to use a Factory pattern to encapsulate the process.
Also. be careful how you name and organise your files. You may find this thread helpful when working with the Rails infectors for classes with numbers in their names. A big part of working with Rails is allowing its magic to work for you rather than unwittingly trying to work against it.
As a general rather than Rails-specific piece of advice, I'd also give a considerable amount of thought to how you could define a common public interface for records that will persist across years. A codebase featuring things like
if record.instance_of? Sample2018Record
record.my_2018_method
elsif record.instance_of? Sample2019Record
record.my_method_only_relevant_to_2019
...
will become very difficult to reason about, especially for developers who join after a couple of years. Ruby has extremely powerful tools to help you duck type very effectively.