Cyclomatic complexity for some_method is too high - ruby

Question

I have following method in controller. When i run lint i get the error
Cyclomatic complexity for some_method is too high
I checked online about it and seems like it is the way i wrote the method. How could i rewrite this method so i dont get the lint error?
def customer_order
if params[:customer_id].present? && !params[:order_id].present?
render_error :not_found, 'No info found for given customer id' \
unless #info.customer_id == params[:customer_id]
elsif params[:order_id].present? && !params[:customer_id].present?
render_error :not_found, 'No info found for given order id' \
unless #info.order_id == params[:order_id]
elsif params[:customer_id].present? && params[:order_id].present?
render_error :not_found, 'No info found for given customer id and order id’ \
unless #info.customer_id == params[:customer_id] &&
#info.order_id == params[:order_id]
end
end

Answer 1

Yikes! It is too high!
This linting message essentially means you have so many if statements that it's hard for a developer to keep straight.
I would suggest refactoring the contents of each if statement into it's own method.
def customer_order
if params[:customer_id].present? && !params[:order_id].present?
no_order_error
elsif params[:order_id].present? && !params[:customer_id].present?
no_info_error
...
end
def no_order_error
return if #info.customer_id == params[:customer_id]
render_error :not_found, 'No info found for given customer id'
end
def no_info_error
...
end

Answer 2

One approach would be to make each of the conditionals their own method. As an example:
def customer_without_order(params)
params[:customer_id].present? && !params[:order_id].present?
end
You may find that the conditionals that determine when you render an error warrant this treatment as well.

Answer 3

You could reduce some of the redundancy like so.
def customer_order
msg = case [params[:customer_id].present?, params[:order_id].present?]
when [true, false]
#info.customer_id == params[:customer_id] ?
nil : 'No info found for given customer id'
when [false, true]
#info.order_id == params[:order_id] ?
nil : 'No info found for given order id'
when [true, true]
#info.customer_id == params[:customer_id] && #info.order_id == params[:order_id] ?
nil : 'No info found for given customer id and order id’
else
nil
end
render_error(:not_found, msg) if msg
end