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Add `create_join_table` migration helper to create HABTM join tables

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1 parent 578c94a commit 080bd83df9ee96845370a73d6152bbe5f231f618 @rafaelfranca rafaelfranca committed Jan 27, 2012
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15 activerecord/CHANGELOG.md
@@ -1,7 +1,18 @@
## Rails 4.0.0 (unreleased) ##
-* The primary key is always initialized in the @attributes hash to nil (unless
- another value has been specified).
+* Added `create_join_table` migration helper to create HABTM join tables
+
+ create_join_table :products, :categories
+ # =>
+ # create_table :categories_products, :id => false do |td|
+ # td.integer :product_id, :null => false
+ # td.integer :category_id, :null => false
+ # end
+
+ *Rafael Mendonça França*
+
+* The primary key is always initialized in the @attributes hash to nil (unless
+ another value has been specified).
* In previous releases, the following would generate a single query with
an `OUTER JOIN comments`, rather than two separate queries:
View
42 activerecord/lib/active_record/connection_adapters/abstract/schema_statements.rb
@@ -1,9 +1,12 @@
require 'active_support/deprecation/reporting'
require 'active_record/schema_migration'
+require 'active_record/migration/join_table'
module ActiveRecord
module ConnectionAdapters # :nodoc:
module SchemaStatements
+ include ActiveRecord::Migration::JoinTable
+
# Returns a Hash of mappings from the abstract data types to the native
# database types. See TableDefinition#column for details on the recognized
# abstract data types.
@@ -170,6 +173,45 @@ def create_table(table_name, options = {})
execute create_sql
end
+ # Creates a new join table with the name created using the lexical order of the first two
+ # arguments. These arguments can be be a String or a Symbol.
+ #
+ # # Creates a table called 'assemblies_parts' with no id.
+ # create_join_table(:assemblies, :parts)
+ #
+ # You can pass a +options+ hash can include the following keys:
+ # [<tt>:table_name</tt>]
+ # Sets the table name overriding the default
+ # [<tt>:column_options</tt>]
+ # Any extra options you want appended to the columns definition.
+ # [<tt>:options</tt>]
+ # Any extra options you want appended to the table definition.
+ # [<tt>:temporary</tt>]
+ # Make a temporary table.
+ # [<tt>:force</tt>]
+ # Set to true to drop the table before creating it.
+ # Defaults to false.
+ #
+ # ===== Examples
+ # ====== Add a backend specific option to the generated SQL (MySQL)
+ # create_join_table(:assemblies, :parts, :options => 'ENGINE=InnoDB DEFAULT CHARSET=utf8')
+ # generates:
+ # CREATE TABLE assemblies_parts (
+ # assembly_id int NOT NULL,
+ # part_id int NOT NULL,
+ # ) ENGINE=InnoDB DEFAULT CHARSET=utf8
+ def create_join_table(table_1, table_2, options = {})
+ join_table_name = find_join_table_name(table_1, table_2, options)
+
+ column_options = options.delete(:column_options) || {}
+ column_options.reverse_merge!({:null => false})
+
+ create_table(join_table_name, options.merge!(:id => false)) do |td|
+ td.integer :"#{table_1.to_s.singularize}_id", column_options
@rohit
rohit added a note Jan 30, 2012

Sorry for nitpicking but isn't there any helper to give the output of this:

"#{table_1.to_s.singularize}_id"
@rafaelfranca
Ruby on Rails member

In this context no. We can refactor the code to include it in this context, but the logic is too simple to require this. But if you want you can try to refactor this to use this helper and send us a pull request ;)

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+ td.integer :"#{table_2.to_s.singularize}_id", column_options
+ end
+ end
+
# A block for changing columns in +table+.
#
# === Example
View
12 activerecord/lib/active_record/migration/command_recorder.rb
@@ -8,11 +8,14 @@ class Migration
# * add_index
# * add_timestamps
# * create_table
+ # * create_join_table
# * remove_timestamps
# * rename_column
# * rename_index
# * rename_table
class CommandRecorder
+ include JoinTable
+
attr_accessor :commands, :delegate
def initialize(delegate = nil)
@@ -48,7 +51,7 @@ def respond_to?(*args) # :nodoc:
super || delegate.respond_to?(*args)
end
- [:create_table, :change_table, :rename_table, :add_column, :remove_column, :rename_index, :rename_column, :add_index, :remove_index, :add_timestamps, :remove_timestamps, :change_column, :change_column_default].each do |method|
+ [:create_table, :create_join_table, :change_table, :rename_table, :add_column, :remove_column, :rename_index, :rename_column, :add_index, :remove_index, :add_timestamps, :remove_timestamps, :change_column, :change_column_default].each do |method|
class_eval <<-EOV, __FILE__, __LINE__ + 1
def #{method}(*args) # def create_table(*args)
record(:"#{method}", args) # record(:create_table, args)
@@ -62,6 +65,12 @@ def invert_create_table(args)
[:drop_table, [args.first]]
end
+ def invert_create_join_table(args)
+ table_name = find_join_table_name(*args)
+
+ [:drop_table, [table_name]]
+ end
+
def invert_rename_table(args)
[:rename_table, args.reverse]
end
@@ -99,7 +108,6 @@ def method_missing(method, *args, &block)
rescue NoMethodError => e
raise e, e.message.sub(/ for #<.*$/, " via proxy for #{@delegate}")
end
-
end
end
end
View
17 activerecord/lib/active_record/migration/join_table.rb
@@ -0,0 +1,17 @@
+module ActiveRecord
+ class Migration
+ module JoinTable #:nodoc:
+ private
+
+ def find_join_table_name(table_1, table_2, options = {})
+ options.delete(:table_name) { join_table_name(table_1, table_2) }
+ end
+
+ def join_table_name(table_1, table_2)
+ tables_names = [table_1, table_2].map(&:to_s).sort
+
+ tables_names.join("_").to_sym
+ end
+ end
+ end
+end
View
1 activerecord/test/cases/migration/change_schema_test.rb
@@ -173,7 +173,6 @@ def test_add_column_not_null_without_default
skip "not supported on #{connection.class}"
end
-
connection.create_table :testings do |t|
t.column :foo, :string
end
View
12 activerecord/test/cases/migration/command_recorder_test.rb
@@ -73,6 +73,18 @@ def test_invert_create_table_with_options
assert_equal [:drop_table, [:people_reminders]], drop_table
end
+ def test_invert_create_join_table
+ @recorder.record :create_join_table, [:musics, :artists]
+ drop_table = @recorder.inverse.first
+ assert_equal [:drop_table, [:artists_musics]], drop_table
+ end
+
+ def test_invert_create_join_table_with_table_name
+ @recorder.record :create_join_table, [:musics, :artists, {:table_name => :catalog}]
+ drop_table = @recorder.inverse.first
+ assert_equal [:drop_table, [:catalog]], drop_table
+ end
+
def test_invert_rename_table
@recorder.record :rename_table, [:old, :new]
rename = @recorder.inverse.first
View
70 activerecord/test/cases/migration/create_join_table_test.rb
@@ -0,0 +1,70 @@
+require 'cases/helper'
+
+module ActiveRecord
+ class Migration
+ class CreateJoinTableTest < ActiveRecord::TestCase
+ attr_reader :connection
+
+ def setup
+ super
+ @connection = ActiveRecord::Base.connection
+ end
+
+ def test_create_join_table
+ connection.create_join_table :artists, :musics
+
+ assert_equal %w(artist_id music_id), connection.columns(:artists_musics).map(&:name).sort
+ ensure
+ connection.drop_table :artists_musics
+ end
+
+ def test_create_join_table_set_not_null_by_default
+ connection.create_join_table :artists, :musics
+
+ assert_equal [false, false], connection.columns(:artists_musics).map(&:null)
+ ensure
+ connection.drop_table :artists_musics
+ end
+
+ def test_create_join_table_with_strings
+ connection.create_join_table 'artists', 'musics'
+
+ assert_equal %w(artist_id music_id), connection.columns(:artists_musics).map(&:name).sort
+ ensure
+ connection.drop_table :artists_musics
+ end
+
+ def test_create_join_table_with_the_proper_order
+ connection.create_join_table :videos, :musics
+
+ assert_equal %w(music_id video_id), connection.columns(:musics_videos).map(&:name).sort
+ ensure
+ connection.drop_table :musics_videos
+ end
+
+ def test_create_join_table_with_the_table_name
+ connection.create_join_table :artists, :musics, :table_name => :catalog
+
+ assert_equal %w(artist_id music_id), connection.columns(:catalog).map(&:name).sort
+ ensure
+ connection.drop_table :catalog
+ end
+
+ def test_create_join_table_with_the_table_name_as_string
+ connection.create_join_table :artists, :musics, :table_name => 'catalog'
+
+ assert_equal %w(artist_id music_id), connection.columns(:catalog).map(&:name).sort
+ ensure
+ connection.drop_table :catalog
+ end
+
+ def test_create_join_table_with_column_options
+ connection.create_join_table :artists, :musics, :column_options => {:null => true}
+
+ assert_equal [true, true], connection.columns(:artists_musics).map(&:null)
+ ensure
+ connection.drop_table :artists_musics
+ end
+ end
+ end
+end
View
30 railties/guides/source/migrations.textile
@@ -114,6 +114,7 @@ database independent way (you'll read about them in detail later):
* +change_column+
* +change_table+
* +create_table+
+* +create_join_table+
* +drop_table+
* +remove_column+
* +remove_index+
@@ -384,6 +385,35 @@ end
will append +ENGINE=BLACKHOLE+ to the SQL statement used to create the table
(when using MySQL, the default is +ENGINE=InnoDB+).
+h4. Creating a Join Table
+
+Migration method +create_join_table+ creates a HABTM join table. A typical use
+would be
+
+<ruby>
+create_join_table :products, :categories
+</ruby>
+
+which creates a +categories_products+ table with two columns called +category_id+ and +product_id+.
+These columns have the option +:null+ set to +false+ by default.
+
+You can pass the option +:table_name+ with you want to customize the table name. For example,
+
+<ruby>
+create_join_table :products, :categories, :table_name => :categorization
+</ruby>
+
+will create a +categorization+ table.
+
+By default, +create_join_table+ will create two columns with no options, but you can specify these
+options using the +:column_options+ option. For example,
+
+<ruby>
+create_join_table :products, :categories, :column_options => {:null => true}
+</ruby>
+
+will create the +product_id+ and +category_id+ with the +:null+ option as +true+.
+
h4. Changing Tables
A close cousin of +create_table+ is +change_table+, used for changing existing

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