SQL92 compatible LIKE escaping

arel_sql92_like_escape.rb

# SQL92 style "LIKE" escaped expression support
#
# load via initializer in Rails
# 
# Arel supports the following expression
#    where(Item.arel_table[:name].matches("%#{str}%") 
# and str have to be escaped.
# The following code specify '!' as an ESCAPE character.
# The target characters to escape are /[%_!]/
# When these characters are escaped with proceeding "!", the following code escapes these character correctly.
# e.g. ...matches("%aa!%bb") matches "XXaa!%bb" but not fot "XXaa!YYbb"
# This code works with MySQL, PostgreSQL and SQLite3 at least.
#
module ArelExt
  module Visitors
    module ToSql
      module InstanceMethods
        def self.included(base)
          base.class_eval do
            alias_method_chain :visit_Arel_Nodes_Matches, :format_sql92
            alias_method_chain :visit_Arel_Nodes_DoesNotMatch, :format_sql92
          end
        end
        def visit_Arel_Nodes_Matches_with_format_sql92 o
          visit_Arel_Nodes_Matches_without_format_sql92(o) + " ESCAPE '!'"
        end

        def visit_Arel_Nodes_DoesNotMatch_with_format_sql92 o
          visit_Arel_Nodes_DoesNotMatch_without_format_sql92(o) + " ESCAPE '!'"
        end
      end
    end
  end
end

ActiveSupport.on_load(:active_record) do
  Arel::Visitors::ToSql.send(:include, ArelExt::Visitors::ToSql::InstanceMethods)
  Arel::Visitors::PostgreSQL.send(:include, ArelExt::Visitors::ToSql::InstanceMethods)
end

Do you have a pull request for this? I'd love to give this a 👍 for what it's worth.

Also: labocho/arel@f436761