From 5730f321d4d5bbd082278fa3e05ad259534780e7 Mon Sep 17 00:00:00 2001
From: James Adam <james@lazyatom.com>
Date: Sat, 21 Feb 2009 15:04:25 +0000
Subject: [PATCH] I believe this is the simplest, consistent mechanism for working with
 migrations from Plugins.

By ensuring the application has a single timeline, migrations can be
applied and reverted in the order they were applied during the
development of the application.

By appending the plugin name to the latter half of the filename, we
can easily detect which migrations from a particular plugin have
already been copied.

I have had to slightly tweak ActiveRecord::Migration so that it will
accept migration names of the form

  <timestamp>_<migration_name>.<plugin_name>.rb

but this change is utterly benign.
---
 activerecord/lib/active_record/migration.rb |    2 +-
 railties/lib/tasks/databases.rake           |   60 +++++++++++++++++++++++++++
 2 files changed, 61 insertions(+), 1 deletions(-)

diff --git a/activerecord/lib/active_record/migration.rb b/activerecord/lib/active_record/migration.rb
index 657acd6..cd671f6 100644
--- a/activerecord/lib/active_record/migration.rb
+++ b/activerecord/lib/active_record/migration.rb
@@ -498,7 +498,7 @@ module ActiveRecord
         files = Dir["#{@migrations_path}/[0-9]*_*.rb"]
         
         migrations = files.inject([]) do |klasses, file|
-          version, name = file.scan(/([0-9]+)_([_a-z0-9]*).rb/).first
+          version, name = file.scan(/([0-9]+)_([_a-z0-9]*)(\..*)?.rb/).first
           
           raise IllegalMigrationNameError.new(file) unless version
           version = version.to_i
diff --git a/railties/lib/tasks/databases.rake b/railties/lib/tasks/databases.rake
index 9588fab..c5c17de 100644
--- a/railties/lib/tasks/databases.rake
+++ b/railties/lib/tasks/databases.rake
@@ -147,6 +147,66 @@ namespace :db do
       ActiveRecord::Migrator.run(:down, "db/migrate/", version)
       Rake::Task["db:schema:dump"].invoke if ActiveRecord::Base.schema_format == :ruby
     end
+    
+    class PluginMigrationHelper
+      def self.with_plugin_migrations
+        plugins_to_migrate = ENV['PLUGINS'] || "*"
+        Dir["vendor/plugins/**/#{plugins_to_migrate}/db/migrate/*.rb"].each do |migration_file|
+          path_parts = migration_file.split("/")
+          plugin_name = path_parts[path_parts.index("migrate")-2]
+          migration_name = File.basename(migration_file, ".rb").split("_")[1..-1].join("_") # without the timestamp
+          yield plugin_name, migration_name, migration_file
+        end
+      end
+    
+      # These are taken from Rails::Generator::Base, it's a shame they can't be easily reused.
+      def self.current_migration_number
+        Dir.glob("#{RAILS_ROOT}/db/migrate/[0-9]*_*.rb").inject(0) do |max, file_path|
+          n = File.basename(file_path).split('_', 2).first.to_i
+          if n > max then n else max end
+        end
+      end
+       
+      def self.next_migration_number
+        current_migration_number + 1
+      end
+
+      def self.next_migration_string(padding = 3)
+        if ActiveRecord::Base.timestamped_migrations
+          Time.now.utc.strftime("%Y%m%d%H%M%S")
+        else
+          "%.#{padding}d" % next_migration_number
+        end
+      end
+    end
+
+    desc 'Copies any missing migrations from plugins into main migration directory. Specify specific plugins via PLUGINS=plugin_a,plugin_b,...'
+    task :plugins do
+      require 'active_record'
+      new_migrations = Hash.new
+      PluginMigrationHelper.with_plugin_migrations do |plugin, migration_name, migration_file|
+        migration_name_with_plugin = "#{migration_name}.#{plugin}.rb"
+        unless Dir.glob("#{RAILS_ROOT}/db/migrate/[0-9]*_#{migration_name_with_plugin}").any?
+          retimestamped_migration = "#{PluginMigrationHelper.next_migration_string}_#{migration_name_with_plugin}"
+          FileUtils.cp(migration_file, "db/migrate/#{retimestamped_migration}")
+          new_migrations[plugin] ||= []
+          new_migrations[plugin] << retimestamped_migration
+        end
+      end
+      if new_migrations.empty?
+        puts "No new migrations found in plugins"
+      else
+        puts "The following new plugin migrations have been copied into your db/migrate directory:\n\n"
+        new_migrations.each do |plugin_name, migrations|
+          puts "from '#{plugin_name}':"
+          migrations.each do |migration_name|
+            puts "\t#{migration_name}"
+          end
+        end
+        puts "\nPlease inspect these files to be SURE you're happy with what they'll do."
+        puts "The migrations will be incorporated the next time you run 'rake db:migrate'."
+      end
+    end
   end
 
   desc 'Rolls the schema back to the previous version. Specify the number of steps with STEP=n'
-- 
1.6.0.1