Created: 2008-07-27 15:13
Updated: 2018-03-27 09:22
License: apache-2.0

dm-is-reflective Build Status

by Lin Jen-Shin (godfat)



DataMapper plugin that helps you manipulate an existing database. It creates mappings between existing columns and model's properties.


  • dm-core
  • choose one: dm-sqlite-adapter, dm-postgres-adapter, dm-mysql-adapter


gem install dm-is-reflective
gem 'dm-is-reflective',
  :git => 'git://',
  :submodules => true


Generating sources from a DATABASE_URI

We also have an executable to generate sources for you.

Usage: dm-is-reflective DATABASE_URI
  -s, --scope SCOPE       SCOPE where the models should go (default: Object)
  -o, --output DIRECTORY  DIRECTORY where the output goes (default: dm-is-reflective)
  -h, --help              Print this message
  -v, --version           Print the version


require 'dm-is-reflective' # this would require 'dm-core'
dm = DataMapper.setup :default, 'sqlite::memory:'

class User
  include DataMapper::Resource
  is :reflective

  # map all, returning an array of properties indicating fields it mapped
  reflect /.*/  # e.g. => [#<Property:#<Class:0x18f89b8>:id>,
                #          #<Property:#<Class:0x18f89b8>:title>,
                #          #<Property:#<Class:0x18f89b8>:body>,
                #          #<Property:#<Class:0x18f89b8>:user_id>]

  # map all (with no argument at all)

  # mapping for field name ended with _at, and started with salt_
  reflect /_at$/, /^salt_/

  # mapping id and email
  reflect :id, :email

  # mapping all fields with type String, and id
  reflect String, :id

  # mapping login, and all fields with type Integer
  reflect :login, Integer

# there's no guarantee of the order in storages array
# => ['users']

# show all indices
dm.indices('users') # [:id, {:unique_index => :users_pkey}]

# there's no guarantee of the order in fields array
# => [[:created_at,  DateTime, {:required => false}],
      [:email,       String,   {:required => false, :length => 255,
                                :default  => ''}],
      [:id,          Serial,   {:required => true, :serial => true,
                                :key      => true}],
      [:salt_first,  String,   {:required => false, :length => 50}],
      [:salt_second, String,   {:required => false, :length => 50}]]

dm.fields('users').sort_by{ |field| field.first.to_s } ==
       User.fields.sort_by{ |field| field.first.to_s }
# => true

# => {'users' => [[:id,          Serial,   {:required => true,
                                            :serial   => true,
                                            :key      => true}],
                  [:email,       String,   {:required => false,
                                            :default  =>
                  [:created_at,  DateTime, {:required => false}],
                  [:salt_first,  String,   {:required => false,
                                            :length   => 50}],
                  [:salt_second, String,   {:required => false,
                                            :length   => 50}]]}

# there's no guarantee of the order in returned array
# => [DataMapper::Is::Reflective::User,

# you can change the scope of generated models:
dm.auto_genclass! :scope => Object
# => [User, SchemaInfo, Session]

# you can generate classes for tables you specified only:
dm.auto_genclass! :scope => Object, :storages => /^phpbb_/
# => [PhpbbUser, PhpbbPost, PhpbbConfig]

# you can generate classes with String too:
dm.auto_genclass! :storages => ['users', 'config'], :scope => Object
# => [User, Config]

# you can generate a class only:
dm.auto_genclass! :storages => 'users'
# => [DataMapper::Is::Reflective::User]

# you can also generate the source from models:
puts User.to_source


  • Andrew Kreps (@onewheelskyward)
  • Lin Jen-Shin (@godfat)
  • Mischa Molhoek (@mmolhoek)
  • @philfine
  • Sebastian Marr (@sebastianmarr)


Apache License 2.0 (Apache-2.0)

Copyright (c) 2008-2017, Lin Jen-Shin (godfat)

Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except in compliance with the License. You may obtain a copy of the License at

Unless required by applicable law or agreed to in writing, software distributed under the License is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the License for the specific language governing permissions and limitations under the License.

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