When running db:migrate on a fresh database, load the database schema before running migrations.

If we have an existing schema file and we run db:migrate before setting up the database, we will not load the schema before running migrations, so when we dump the schema will overwrite the existing schema file and lose the tables define there. Instead, we should check if the db is setup and if it is not lload the schema, before running migrations.

Author: andrewn617

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"]