Merge pull request rails#52830 from Shopify/load-schema-on-migrating-new-database

Load schema when running db:migrate on fresh db

Author: rafaelfranca

activerecord/CHANGELOG.md

@@ -1,3 +1,7 @@
+*   When running `db:migrate` on a fresh database, load the database schema before running migrations.
+
+    *Andrew Novoselac*
+
 *   Fix an issue where `.left_outer_joins` used with multiple associations that have
     the same child association but different parents does not join all parents.
 

activerecord/lib/active_record/tasks/database_tasks.rb

@@ -178,22 +178,9 @@ def prepare_all
         dump_db_configs = []
 
         each_current_configuration(env) do |db_config|
-          with_temporary_pool(db_config) do
-            begin
-              database_initialized = migration_connection_pool.schema_migration.table_exists?
-            rescue ActiveRecord::NoDatabaseError
-              create(db_config)
-              retry
-            end
+          database_initialized = initialize_database(db_config)
 
-            unless database_initialized
-              if File.exist?(schema_dump_path(db_config))
-                load_schema(db_config, ActiveRecord.schema_format, nil)
-              end
-
-              seed = true
-            end
-          end
+          seed = true if database_initialized
         end
 
         each_current_environment(env) do |environment|
@@ -259,6 +246,8 @@ def migrate(version = nil)
 
         check_target_version
 
+        initialize_database(migration_connection_pool.db_config)
+
         migration_connection_pool.migration_context.migrate(target_version) do |migration|
           if version.blank?
             scope.blank? || scope == migration.scope
@@ -667,6 +656,26 @@ def check_current_protected_environment!(db_config)
           rescue ActiveRecord::NoDatabaseError
           end
         end
+
+        def initialize_database(db_config)
+          with_temporary_pool(db_config) do
+            begin
+              database_already_initialized = migration_connection_pool.schema_migration.table_exists?
+            rescue ActiveRecord::NoDatabaseError
+              create(db_config)
+              retry
+            end
+
+            unless database_already_initialized
+              schema_dump_path = schema_dump_path(db_config)
+              if schema_dump_path && File.exist?(schema_dump_path)
+                load_schema(db_config, ActiveRecord.schema_format, nil)
+              end
+            end
+
+            !database_already_initialized
+          end
+        end
     end
   end
 end

railties/test/application/rake/dbs_test.rb

@@ -350,6 +350,19 @@ def db_migrate_and_status(expected_database)
         db_migrate_and_status database_url_db_name
       end
 
+      test "db:migrate on new db loads schema" do
+        app_file "db/schema.rb", <<-RUBY
+          ActiveRecord::Schema.define(version: 20140423102712) do
+            create_table(:comments) {}
+          end
+        RUBY
+
+        rails "db:migrate"
+        list_tables = lambda { rails("runner", "p ActiveRecord::Base.lease_connection.tables.sort").strip }
+
+        assert_equal "[\"ar_internal_metadata\", \"comments\", \"schema_migrations\"]", list_tables[]
+      end
+
       def db_schema_dump
         Dir.chdir(app_path) do
           args = ["generate", "model", "book", "title:string"]