dm_can_haz_text_for_json.rb

#This Ugly hack adds Json as one of the types hardcoded to use TEXT.
#
# The problem this solves is this
#
# class A
#   include DataMapper::Resource
#   property :id, Serial
#   property :stuff, DataMapper::Types::Json
#  end
# DataMapper.auto_migrate!
# #=>sql statement:
# CREATE TABLE `as` (`id` INT(10) UNSIGNED NOT NULL AUTO_INCREMENT, `stuff` VARCHAR(65535), PRIMARY KEY(`id`))...
# VARCHAR cannot be that big, so it fails.
#
# It would be better if the mapping was less reliant on class.
# text_column_statement[1] already chooses the primitive type depending
# on the length, so why not use the type's length to determine what
# it is in the db?
#
# The logic for doing this probably would go somewhere like property_schema_hash[2]
#
# [1] http://github.com/datamapper/dm-core/blob/master/lib/dm-core/migrations.rb#L432
# [2] http://github.com/datamapper/dm-core/blob/master/lib/dm-core/migrations.rb#L243

   module DataMapper
      module Adapters
        class DataObjectsAdapter < AbstractAdapter
          class <<self
            # Default types for all data object based adapters.
            #
            # @return [Hash] default types for data objects adapters.
            #
            # @api private
            def type_map
              length = Property::DEFAULT_LENGTH
              precision = Property::DEFAULT_PRECISION
              scale = Property::DEFAULT_SCALE_BIGDECIMAL
     
              @type_map ||= {
                Integer => { :primitive => 'INTEGER' },
                String => { :primitive => 'VARCHAR', :length => length },
                Class => { :primitive => 'VARCHAR', :length => length },
                BigDecimal => { :primitive => 'DECIMAL', :precision => precision, :scale => scale },
                Float => { :primitive => 'FLOAT', :precision => precision },
                DateTime => { :primitive => 'TIMESTAMP' },
                Date => { :primitive => 'DATE' },
                Time => { :primitive => 'TIMESTAMP' },
                TrueClass => { :primitive => 'BOOLEAN' },
                Types::Object => { :primitive => 'TEXT' },
                Types::Text => { :primitive => 'MEDIUMTEXT' },
                Types::Json=> { :primitive => 'MEDIUMTEXT' }, #<-- support for types from dm-types
                #...
              }.freeze
            end
          end
        end
      end
    end