Switched to UTC-timebased version numbers for migrations and the schema. This will as good as eliminate the problem of multiple migrations getting the same version assigned in different branches. Also added rake db:migrate:up/down to apply individual migrations that may need to be run when you merge branches (closes #11458) [jbarnette]

git-svn-id: http://svn-commit.rubyonrails.org/rails/trunk@9122 5ecf4fe2-1ee6-0310-87b1-e25e094e27de

1 files changed, 87 insertions, 61 deletions

diff --git a/activerecord/lib/active_record/migration.rb b/activerecord/lib/active_record/migration.rb
index 9945f9cd75..58374a01ad 100644
--- a/activerecord/lib/active_record/migration.rb
+++ b/activerecord/lib/active_record/migration.rb
@@ -8,6 +8,12 @@ module ActiveRecord
     end
   end
 
+  class UnknownMigrationVersionError < ActiveRecordError #:nodoc:
+    def initialize(version)
+      super("No migration with version number #{version}")
+    end
+  end
+
   class IllegalMigrationNameError < ActiveRecordError#:nodoc:
     def initialize(name)
       super("Illegal name for migration file: #{name}\n\t(only lower case letters, numbers, and '_' allowed)")
@@ -308,8 +314,6 @@ module ActiveRecord
   class Migrator#:nodoc:
     class << self
       def migrate(migrations_path, target_version = nil)
-        Base.connection.initialize_schema_information
-
         case
           when target_version.nil?, current_version < target_version
             up(migrations_path, target_version)
@@ -319,6 +323,16 @@ module ActiveRecord
             return # You're on the right version
         end
       end
+      
+      def rollback(migrations_path, steps=1)
+        migrator = self.new(:down, migrations_path)
+        start_index = migrator.migrations.index(migrator.current_migration)
+        
+        return unless start_index
+        
+        finish = migrator.migrations[start_index + steps]
+        down(migrations_path, finish ? finish.version : 0)
+      end
 
       def up(migrations_path, target_version = nil)
         self.new(:up, migrations_path, target_version).migrate
@@ -327,6 +341,10 @@ module ActiveRecord
       def down(migrations_path, target_version = nil)
         self.new(:down, migrations_path, target_version).migrate
       end
+      
+      def run(direction, migrations_path, target_version)
+        self.new(direction, migrations_path, target_version)
+      end
 
       def schema_info_table_name
         Base.table_name_prefix + "schema_info" + Base.table_name_suffix
@@ -344,73 +362,90 @@ module ActiveRecord
 
     def initialize(direction, migrations_path, target_version = nil)
       raise StandardError.new("This database does not yet support migrations") unless Base.connection.supports_migrations?
-      @direction, @migrations_path, @target_version = direction, migrations_path, target_version
       Base.connection.initialize_schema_information
+      @direction, @migrations_path, @target_version = direction, migrations_path, target_version      
     end
 
     def current_version
       self.class.current_version
     end
+    
+    def current_migration
+      migrations.detect { |m| m.version == current_version }
+    end
+    
+    def run
+      target = migrations.detect { |m| m.version == @target_version }
+      raise UnknownMigrationVersionError.new(@target_version) if target.nil?
+      target.migrate(@direction)
+    end
 
     def migrate
-      migration_classes.each do |migration_class|
-        if reached_target_version?(migration_class.version)
-          Base.logger.info("Reached target version: #{@target_version}")
-          break
-        end
-
-        next if irrelevant_migration?(migration_class.version)
+      current = migrations.detect { |m| m.version == current_version }
+      target = migrations.detect { |m| m.version == @target_version }
+            
+      if target.nil? && !@target_version.nil? && @target_version > 0
+        raise UnknownMigrationVersionError.new(@target_version)
+      end
+      
+      start = migrations.index(current) || 0
+      finish = migrations.index(target) || migrations.size - 1      
+      runnable = migrations[start..finish]
+      
+      # skip the current migration if we're heading upwards
+      runnable.shift if up? && runnable.first == current
+      
+      # skip the last migration if we're headed down, but not ALL the way down
+      runnable.pop if down? && !target.nil?
+      
+      runnable.each do |migration|
+        Base.logger.info "Migrating to #{migration} (#{migration.version})"
+        migration.migrate(@direction)
+        set_schema_version_after_migrating(migration)
+      end
+    end
 
-        Base.logger.info "Migrating to #{migration_class} (#{migration_class.version})"
-        migration_class.migrate(@direction)
-        set_schema_version(migration_class.version)
+    def migrations
+      @migrations ||= begin
+        files = Dir["#{@migrations_path}/[0-9]*_*.rb"]
+        
+        migrations = files.inject([]) do |klasses, file|
+          version, name = file.scan(/([0-9]+)_([_a-z0-9]*).rb/).first
+          
+          raise IllegalMigrationNameError.new(f) unless version
+          version = version.to_i
+          
+          if klasses.detect { |m| m.version == version }
+            raise DuplicateMigrationVersionError.new(version) 
+          end
+          
+          load(file)
+          
+          klasses << returning(name.camelize.constantize) do |klass|
+            class << klass; attr_accessor :version end
+            klass.version = version
+          end
+        end
+        
+        migrations = migrations.sort_by(&:version)
+        down? ? migrations.reverse : migrations
       end
     end
 
     def pending_migrations
-      migration_classes.select { |m| m.version > current_version }
+      migrations.select { |m| m.version > current_version }
     end
 
     private
-      def migration_classes
-        classes = migration_files.inject([]) do |migrations, migration_file|
-          load(migration_file)
-          version, name = migration_version_and_name(migration_file)
-          assert_unique_migration_version(migrations, version.to_i)
-          migrations << migration_class(name, version.to_i)
-        end.sort_by(&:version)
-
-        down? ? classes.reverse : classes
-      end
-
-      def assert_unique_migration_version(migrations, version)
-        if !migrations.empty? && migrations.find { |m| m.version == version }
-          raise DuplicateMigrationVersionError.new(version)
-        end
-      end
-
-      def migration_files
-        files = Dir["#{@migrations_path}/[0-9]*_*.rb"].sort_by do |f|
-          m = migration_version_and_name(f)
-          raise IllegalMigrationNameError.new(f) unless m
-          m.first.to_i
+      def set_schema_version_after_migrating(migration)
+        version = migration.version
+            
+        if down?
+          after = migrations[migrations.index(migration) + 1]
+          version = after ? after.version : 0
         end
-        down? ? files.reverse : files
-      end
-
-      def migration_class(migration_name, version)
-        klass = migration_name.camelize.constantize
-        class << klass; attr_accessor :version end
-        klass.version = version
-        klass
-      end
-
-      def migration_version_and_name(migration_file)
-        return *migration_file.scan(/([0-9]+)_([_a-z0-9]*).rb/).first
-      end
-
-      def set_schema_version(version)
-        Base.connection.update("UPDATE #{self.class.schema_info_table_name} SET version = #{down? ? version.to_i - 1 : version.to_i}")
+            
+        Base.connection.update("UPDATE #{self.class.schema_info_table_name} SET version = #{version}")
       end
 
       def up?
@@ -420,14 +455,5 @@ module ActiveRecord
       def down?
         @direction == :down
       end
-
-      def reached_target_version?(version)
-        return false if @target_version == nil
-        (up? && version.to_i - 1 >= @target_version) || (down? && version.to_i <= @target_version)
-      end
-
-      def irrelevant_migration?(version)
-        (up? && version.to_i <= current_version) || (down? && version.to_i > current_version)
-      end
   end
 end