Fix the array handling on ActiveRecord's prepared statements

predicate_builder_array_fix.rb

# frozen_string_literal: true

# Before (creates prepared statement for each varying size of given array):
# 
#    $ Post.where(id: [uuid1, uuid2])
#    => Post Load (0.6ms)  SELECT "posts".* FROM "posts" WHERE "posts"."id" IN ($1, $2)  [["id", "a830f21d-a27b-4bde-8c05-6e5dd088712e"], ["id","531ee026-d60d-4a59-a9a5-d44c44578a98}"]]
#
# After (the only one statement for varying size of given array):
#
#    $ Post.where(id: [uuid1, uuid2])
#    => Post Load (0.6ms)  SELECT "posts".* FROM "posts" WHERE "posts"."id" = ANY($1)  [["id", "{a830f21d-a27b-4bde-8c05-6e5dd088712e,531ee026-d60d-4a59-a9a5-d44c44578a98}"]]

module PredicateBuilderArrayFix
  module BuilderHook
    def build_bind_attribute(column_name, value)
      if value.is_a?(Array)
        column_type = table.type(column_name.to_sym).type
        array_type = Type.lookup(column_type, array: true)
        attr = Relation::QueryAttribute.new(column_name, value, array_type)
        Arel::Nodes::BindParam.new(attr)
      else
        super
      end
    end
  end
  
  module HandlerHook
    def call(attribute, value)
      return attribute.in([]) if value.empty?

      values = value.map { |x| x.is_a?(Base) ? x.id : x }
      nils, values = values.partition(&:nil?)
      ranges, values = values.partition { |v| v.is_a?(Range) }

      values_predicate =
        case values.length
        when 0 then NullPredicate
        when 1 then predicate_builder.build(attribute, values.first)
        else
          values = predicate_builder.build_bind_attribute(attribute.name, values)
          attribute.eq(Arel::Nodes::NamedFunction.new("ANY", [values]))
        end

      unless nils.empty?
        values_predicate = values_predicate.or(predicate_builder.build(attribute, nil))
      end

      array_predicates = ranges.map { |range| predicate_builder.build(attribute, range) }
      array_predicates.unshift(values_predicate)
      array_predicates.inject(&:or)
    end
  end
end

ActiveSupport.on_load(:active_record) do
  ActiveRecord::PredicateBuilder.prepend(PredicateBuilderArrayFix::BuilderHook)
  ActiveRecord::PredicateBuilder::ArrayHandler.prepend(PredicateBuilderArrayFix::HandlerHook)
end

Elegantly fixes rails/rails#33702