Ruby on Rails ActiveRecord How to get a where clause to always evaluate to be true

Question

I am making a simple resource app. The app has filters in three major categories (courses, years, resource type) that may or may not be present. These filters are passed through parameters in an URL. I store these parameters in an 3 arrays called courses, years, resource type. However sometimes the array may be empty. When I try to run a search with an empty array (ex. maybe resourceType is empty so I want a particular resource from a particular year but it can be of any type), it returns a empty set. Is there a way to use a wild card in this function? If not can someone propose a suitable solution?

Here is the function I am trying to run.

     @resources= Resource.where(class_name: courses, 
                          year: years, 
                          resource_type: resourceTypes)
                          .paginate(page: params[:page], per_page: 10)
                          .order(:cached_votes_total => :desc)

Answer 1

You could always do something like:

@resources = Resource.all
@resources = @resources.where(class_name: courses) if courses.any? 
@resources = @resources.where(resource_type: resourceTypes) if resourceTypes.any? 
@resources = @resources.where(year: years) if years.any? 
@resources = @resources.paginate(page: params[:page], per_page: 10).order(:cached_votes_total => :desc)

Answer 2

Try:

query = { }

query[:class_name] = courses if courses.present?
query[:year] = years if years.present?
query[:resource_type] = coursresourceTypeses if coursresourceTypeses.present?

@resources = Resource.where(query).paginate(page: params[:page], per_page: 10).order(cached_votes_total: :desc)