models: refactor class methods into scopes.

app/models/post_appeal.rb

@@ -10,19 +10,11 @@ class PostAppeal < ApplicationRecord
   validate :validate_creator_is_not_limited
   validates_uniqueness_of :creator_id, :scope => :post_id, :message => "have already appealed this post"
 
+  scope :resolved, -> { where(post: Post.undeleted.unflagged) }
+  scope :unresolved, -> { where(post: Post.deleted.or(Post.flagged)) }
+  scope :recent, -> { where("post_appeals.created_at >= ?", 1.day.ago) }
+
   module SearchMethods
-    def resolved
-      joins(:post).where("posts.is_deleted = false and posts.is_flagged = false")
-    end
-
-    def unresolved
-      joins(:post).where("posts.is_deleted = true or posts.is_flagged = true")
-    end
-
-    def recent
-      where("created_at >= ?", 1.day.ago)
-    end
-
     def search(params)
       q = super
       q = q.search_attributes(params, :creator, :post, :reason)