Sorting

Use sort_by to define how the resource list will be sorted on the index action.

module Projects
  class Resource < ApplicationResource
    sort_by created_at: :desc
  end
end

There are two ways of using sort_by:

1. If it is an attribute, the list will be sorted by it. Internally, it uses order(sort_by). You can pass one or more attributes:

sort_by foo: :asc, bar: desc

2. If it is the name of a method, it can accept zero, one or two arguments. Declare that method inside the model. The method should return an ActiveRecord::Relation. It will be chained with other methods of the collection (pagination, etc.)

The index action accepts the query parameters order_by and order. It will call the sorting method with the parameters that it receives, so take care to make your method respond to the correct number of parameters.

if order_by && order
  # call sorting method with order_by, order
elsif order_by
  # call sorting method with order_by
elsif order
  # call sorting method with order
else
  # call sorting method without arguments
end

Example of a sorting method without parameters:

# app/resources/lists/resource
module Lists
  class Resource < ApplicationResource
    filter_by :project, optional: true

    sort_by :sorting

    extend_model do
      def self.sorting # without arguments
        joins(:project).order('projects.name asc')
      end
    end
  end
end

Example of a sorting method with parameters:

# app/resources/lists/resource
module Lists
  class Resource < ApplicationResource
    filter_by :project, optional: true

    sort_by :sorting

    extend_model do
      def self.sorting(order_by, order) # with arguments
        # if order_by isn't present and order is, the method will receive the latter as the first argument, so be careful with the usage
        sort = parse_sorting_names(order_by) || 'created_at'
        joins(:project).order(sort => order || 'asc')
      end

      def self.parse_sorting_names(order_by)
        return 'projects.name' if order_by == 'project_name'

        order_by
      end
    end
  end
end

The method could also receive only one of the parameters. Just be careful because if you accept order_by and the request happens to pass only the parameter order, it will be passed as the first and only argument.