Move seed.interesting to a scope

app/models/seed.rb

@@ -31,7 +31,8 @@ class Seed < ActiveRecord::Base
     allow_nil: true
 
   scope :tradable, -> { where("tradable_to != 'nowhere'") }
-
+  scope :interesting, -> { tradable.has_location }
+  scope :has_location, -> { joins(:owner).where.not("members.location": nil) }
   TRADABLE_TO_VALUES = %w(nowhere locally nationally internationally).freeze
   validates :tradable_to, inclusion: { in: TRADABLE_TO_VALUES,
                                        message: "You may only trade seed nowhere, "\
@@ -77,27 +78,6 @@ class Seed < ActiveRecord::Base
     end
   end
 
-  def interesting?
-    # assuming we're passed something that's already known to be tradable
-    # eg. from Seed.tradable scope
-    return false if owner.location.blank? # don't want unspecified locations
-    true
-  end
-
-  # Seed.interesting
-  # returns a list of interesting seeds, for use on the homepage etc
-  def self.interesting
-    howmany = 12 # max number to find
-    interesting_seeds = []
-
-    Seed.tradable.each do |s|
-      break if interesting_seeds.size == howmany
-      interesting_seeds.push(s) if s.interesting?
-    end
-
-    interesting_seeds
-  end
-
   def seed_slug
     "#{owner.login_name}-#{crop}".downcase.tr(' ', '-')
   end