Add migration history to schema.rb dump

activerecord/CHANGELOG.md

 ## Rails 4.0.0 (unreleased) ##
 
+*   Add migration history to schema.rb dump.
+    Loading schema.rb with full migration history
+    restores the exact list of migrations that created
+    that schema (including names and fingerprints). This
+    avoids possible mistakes caused by assuming all
+    migrations with a lower version have been run when
+    loading schema.rb. Old schema.rb files without migration
+    history but with the :version setting still work as before.
+
+    *Josh Susser*
+
 *   Add metadata columns to schema_migrations table.
     New columns are: migrated_at (timestamp),
     fingerprint (md5 hash of migration source), and

activerecord/lib/active_record/connection_adapters/abstract/schema_statements.rb

@@ -490,8 +490,8 @@ def dump_schema_information #:nodoc:
         sm_table = ActiveRecord::Migrator.schema_migrations_table_name
 
         ActiveRecord::SchemaMigration.order('version').map { |sm|
-          "INSERT INTO #{sm_table} (version, migrated_at, name) VALUES ('#{sm.version}',LOCALTIMESTAMP,'#{sm.name}');"
-        }.join "\n\n"
+          "INSERT INTO #{sm_table} (version, migrated_at, fingerprint, name) VALUES ('#{sm.version}',LOCALTIMESTAMP,'#{sm.fingerprint}','#{sm.name}');"
+        }.join("\n\n")
       end
 
       # Should not be called normally, but this operation is non-destructive.

activerecord/lib/active_record/schema.rb

@@ -34,27 +34,45 @@ def migrations_paths
     end
 
     def define(info, &block)
+      @using_deprecated_version_setting = info[:version].present?
+      SchemaMigration.drop_table
+      initialize_schema_migrations_table
+
       instance_eval(&block)
 
-      unless info[:version].blank?
-        initialize_schema_migrations_table
-        assume_migrated_upto_version(info[:version], migrations_paths)
-      end
+      # handle files from pre-4.0 that used :version option instead of dumping migration table
+      assume_migrated_upto_version(info[:version], migrations_paths) if @using_deprecated_version_setting
     end
 
     # Eval the given block. All methods available to the current connection
     # adapter are available within the block, so you can easily use the
     # database definition DSL to build up your schema (+create_table+,
     # +add_index+, etc.).
-    #
-    # The +info+ hash is optional, and if given is used to define metadata
-    # about the current schema (currently, only the schema's version):
-    #
-    #   ActiveRecord::Schema.define(version: 20380119000001) do
-    #     ...
-    #   end
     def self.define(info={}, &block)
       new.define(info, &block)
     end
+
+    # Create schema migration history. Include migration statements in a block to this method.
+    #
+    #   migrations do
+    #     migration 20121128235959, "44f1397e3b92442ca7488a029068a5ad", "add_horn_color_to_unicorns"
+    #     migration 20121129235959, "4a1eb3965d94406b00002b370854eae8", "add_magic_power_to_unicorns"
+    #   end
+    def migrations
+      raise(ArgumentError, "Can't set migrations while using :version option") if @using_deprecated_version_setting
+      yield
+    end
+
+    # Add a migration to the ActiveRecord::SchemaMigration table.
+    #
+    # The +version+ argument is an integer.
+    # The +fingerprint+ and +name+ arguments are required but may be empty strings.
+    # The migration's +migrated_at+ attribute is set to the current time,
+    # instead of being set explicitly as an argument to the method.
+    #
+    #   migration 20121129235959, "4a1eb3965d94406b00002b370854eae8", "add_magic_power_to_unicorns"
+    def migration(version, fingerprint, name)
+      SchemaMigration.create!(version: version, migrated_at: Time.now, fingerprint: fingerprint, name: name)
+    end
   end
 end

activerecord/lib/active_record/schema_dumper.rb

@@ -24,6 +24,7 @@ def self.dump(connection=ActiveRecord::Base.connection, stream=STDOUT)
 
     def dump(stream)
       header(stream)
+      migrations(stream)
       tables(stream)
       trailer(stream)
       stream
@@ -44,7 +45,7 @@ def header(stream)
           stream.puts "# encoding: #{stream.external_encoding.name}"
         end
 
-        stream.puts <<HEADER
+        header_text = <<HEADER_RUBY
 # This file is auto-generated from the current state of the database. Instead
 # of editing this file, please use the migrations feature of Active Record to
 # incrementally modify your database, and then regenerate this schema definition.
@@ -59,13 +60,25 @@ def header(stream)
 
 ActiveRecord::Schema.define(#{define_params}) do
 
-HEADER
+HEADER_RUBY
+        stream.puts header_text
       end
 
       def trailer(stream)
         stream.puts "end"
       end
 
+      def migrations(stream)
+        all_migrations = ActiveRecord::SchemaMigration.all.to_a
+        if all_migrations.any?
+          stream.puts("  migrations do")
+          all_migrations.each do |migration|
+            stream.puts(migration.schema_line("    "))
+          end
+          stream.puts("  end")
+        end
+      end
+
       def tables(stream)
         @connection.tables.sort.each do |tbl|
           next if ['schema_migrations', ignore_tables].flatten.any? do |ignored|

activerecord/lib/active_record/schema_migration.rb

@@ -53,5 +53,17 @@ def self.drop_table
     def version
       super.to_i
     end
+
+    # Construct ruby source to include in schema.rb dump for this migration.
+    # Pass a string of spaces as +indent+ to allow calling code to control how deeply indented the line is.
+    # The generated line includes the migration version, fingerprint, and name. Either fingerprint or name
+    # can be an empty string.
+    #
+    # Example output:
+    #
+    #   migration 20121129235959, "ee4be703f9e6e2fc0f4baddebe6eb8f7", "add_magic_power_to_unicorns"
+    def schema_line(indent)
+      %Q(#{indent}migration %s, "%s", "%s") % [version, fingerprint, name]
+    end
   end
 end

activerecord/test/cases/ar_schema_test.rb

@@ -46,4 +46,55 @@ def test_schema_subclass
     end
   end
 
+  class ActiveRecordSchemaMigrationsTest < ActiveRecordSchemaTest
+    def setup
+      super
+      ActiveRecord::SchemaMigration.delete_all
+    end
+
+    def test_migration_adds_row_to_migrations_table
+      schema = ActiveRecord::Schema.new
+      schema.migration(1001, "", "")
+      schema.migration(1002, "123456789012345678901234567890ab", "add_magic_power_to_unicorns")
+
+      migrations = ActiveRecord::SchemaMigration.all.to_a
+      assert_equal 2, migrations.length
+
+      assert_equal 1001, migrations[0].version
+      assert_match %r{^2\d\d\d-}, migrations[0].migrated_at.to_s(:db)
+      assert_equal "", migrations[0].fingerprint
+      assert_equal "", migrations[0].name
+
+      assert_equal 1002, migrations[1].version
+      assert_match %r{^2\d\d\d-}, migrations[1].migrated_at.to_s(:db)
+      assert_equal "123456789012345678901234567890ab", migrations[1].fingerprint
+      assert_equal "add_magic_power_to_unicorns", migrations[1].name
+    end
+
+    def test_define_clears_schema_migrations
+      assert_nothing_raised do
+        ActiveRecord::Schema.define do
+          migrations do
+            migration(123001, "", "")
+          end
+        end
+        ActiveRecord::Schema.define do
+          migrations do
+            migration(123001, "", "")
+          end
+        end
+      end
+    end
+
+    def test_define_raises_if_both_version_and_explicit_migrations
+      assert_raise(ArgumentError) do
+        ActiveRecord::Schema.define(version: 123001) do
+          migrations do
+            migration(123001, "", "")
+          end
+        end
+      end
+    end
+  end
+
 end

activerecord/test/cases/schema_dumper_test.rb

 require "cases/helper"
-
+# require "cases/migration/helper"
 
 class SchemaDumperTest < ActiveRecord::TestCase
   def setup
@@ -18,11 +18,15 @@ def standard_dump
   def test_dump_schema_information_outputs_lexically_ordered_versions
     versions = %w{ 20100101010101 20100201010101 20100301010101 }
     versions.reverse.each do |v|
-      ActiveRecord::SchemaMigration.create!(:version => v, :name => "anon", :migrated_at => Time.now)
+      ActiveRecord::SchemaMigration.create!(
+        :version => v, :migrated_at => Time.now,
+        :fingerprint => "123456789012345678901234567890ab", :name => "anon")
     end
 
     schema_info = ActiveRecord::Base.connection.dump_schema_information
     assert_match(/20100201010101.*20100301010101/m, schema_info)
+    target_line = %q{INSERT INTO schema_migrations (version, migrated_at, fingerprint, name) VALUES ('20100101010101',LOCALTIMESTAMP,'123456789012345678901234567890ab','anon');}
+    assert_match target_line, schema_info
   end
 
   def test_magic_comment
@@ -36,6 +40,16 @@ def test_schema_dump
     assert_no_match %r{create_table "schema_migrations"}, output
   end
 
+  def test_schema_dump_includes_migrations
+    ActiveRecord::SchemaMigration.delete_all
+    ActiveRecord::Migrator.migrate(MIGRATIONS_ROOT + "/always_safe")
+
+    output = standard_dump
+    assert_match %r{migrations do}, output, "Missing migrations block"
+    assert_match %r{migration 1001, "[0-9a-f]{32}", "always_safe"}, output, "Missing migration line"
+    assert_match %r{migration 1002, "[0-9a-f]{32}", "still_safe"},  output, "Missing migration line"
+  end
+
   def test_schema_dump_excludes_sqlite_sequence
     output = standard_dump
     assert_no_match %r{create_table "sqlite_sequence"}, output

activerecord/test/migrations/always_safe/1001_always_safe.rb

+class AlwaysSafe < ActiveRecord::Migration
+  def change
+    # do nothing to avoid side-effect conflicts from running multiple times
+  end
+end

activerecord/test/migrations/always_safe/1002_still_safe.rb

+class StillSafe < ActiveRecord::Migration
+  def change
+    # do nothing to avoid side-effect conflicts from running multiple times
+  end
+end