undefined local variable or method `per' for []:ActiveRecord::Relation

bug:

undefined local variable or method `per' for []:ActiveRecord::Relation

查看gemfile发现下面两行代码
gem "exception_logger", :github => "ryancheung/exception_logger"
gem 'kaminari'

因为gem 'exception_logger' 会依赖will_paginate这个gem，这会与gem 'kaminari'产生冲突，导致方法错乱，以导致代码报错
解决的方法：
创建文件 config/initializers/kaminari.rb

if defined?(WillPaginate)
  module WillPaginate
    module ActiveRecord
      module RelationMethods
        alias_method :per, :per_page
        alias_method :num_pages, :total_pages
        alias_method :prev_page, :previous_page
      end
    end
  end
end