Support hash config for `structure_dump_flags` and `structure_load_flags` flags

Now that Active Record supports multiple databases configuration
    we need a way to pass specific flags for dump/load databases since
    the options are not the same for different adapters.
    We can use in the original way:
    ```ruby
    ActiveRecord::Tasks::DatabaseTasks.structure_dump_flags = ['--no-defaults', '--skip-add-drop-table']
    #or
    ActiveRecord::Tasks::DatabaseTasks.structure_dump_flags = '--no-defaults --skip-add-drop-table'
    ```
    And also use it passing a hash, with one or more keys, where the key
    is the adapter
    ```ruby
    ActiveRecord::Tasks::DatabaseTasks.structure_dump_flags = {
      mysql2: ['--no-defaults', '--skip-add-drop-table'],
      postgres: '--no-tablespaces'
    }
    ```

activerecord/CHANGELOG.md

@@ -1,3 +1,27 @@
+*   Support hash config for `structure_dump_flags` and `structure_load_flags` flags
+    Now that Active Record supports multiple databases configuration
+    we need a way to pass specific flags for dump/load databases since
+    the options are not the same for different adapters.
+    We can use in the original way:
+
+    ```ruby
+    ActiveRecord::Tasks::DatabaseTasks.structure_dump_flags = ['--no-defaults', '--skip-add-drop-table']
+    #or
+    ActiveRecord::Tasks::DatabaseTasks.structure_dump_flags = '--no-defaults --skip-add-drop-table'
+    ```
+     
+    And also use it passing a hash, with one or more keys, where the key
+    is the adapter
+
+    ```ruby
+    ActiveRecord::Tasks::DatabaseTasks.structure_dump_flags = {
+      mysql2: ['--no-defaults', '--skip-add-drop-table'],
+      postgres: '--no-tablespaces'
+    }    
+    ```
+
+    *Gustavo Gonzalez*
+
 *   Connection specification now passes the "url" key as a configuration for the
     adapter if the "url" protocol is "jdbc", "http", or "https". Previously only
     urls with the "jdbc" prefix were passed to the Active Record Adapter, others

activerecord/lib/active_record/tasks/database_tasks.rb

@@ -39,11 +39,18 @@ module ActiveRecord
       ##
       # :singleton-method:
       # Extra flags passed to database CLI tool (mysqldump/pg_dump) when calling db:schema:dump
+      # It can be used as a string/array (the typical case) or a hash (when you use multiple adapters)
+      # Example:
+      #   ActiveRecord::Tasks::DatabaseTasks.structure_dump_flags = {
+      #     mysql2: ['--no-defaults', '--skip-add-drop-table'],
+      #     postgres: '--no-tablespaces'
+      #   }
       mattr_accessor :structure_dump_flags, instance_accessor: false
 
       ##
       # :singleton-method:
       # Extra flags passed to database CLI tool when calling db:schema:load
+      # It can be used as a string/array (the typical case) or a hash (when you use multiple adapters)
       mattr_accessor :structure_load_flags, instance_accessor: false
 
       extend self
@@ -338,13 +345,15 @@ module ActiveRecord
       def structure_dump(configuration, *arguments)
         db_config = resolve_configuration(configuration)
         filename = arguments.delete_at(0)
-        database_adapter_for(db_config, *arguments).structure_dump(filename, structure_dump_flags)
+        flags = structure_dump_flags_for(db_config.adapter)
+        database_adapter_for(db_config, *arguments).structure_dump(filename, flags)
       end
 
       def structure_load(configuration, *arguments)
         db_config = resolve_configuration(configuration)
         filename = arguments.delete_at(0)
-        database_adapter_for(db_config, *arguments).structure_load(filename, structure_load_flags)
+        flags = structure_load_flags_for(db_config.adapter)
+        database_adapter_for(db_config, *arguments).structure_load(filename, flags)
       end
 
       def load_schema(db_config, format = ActiveRecord::Base.schema_format, file = nil) # :nodoc:
@@ -566,6 +575,22 @@ module ActiveRecord
         def schema_sha1(file)
           Digest::SHA1.hexdigest(File.read(file))
         end
+
+        def structure_dump_flags_for(adapter)
+          if structure_dump_flags.is_a?(Hash)
+            structure_dump_flags[adapter.to_sym]
+          else
+            structure_dump_flags
+          end
+        end
+
+        def structure_load_flags_for(adapter)
+          if structure_load_flags.is_a?(Hash)
+            structure_load_flags[adapter.to_sym]
+          else
+            structure_load_flags
+          end
+        end
     end
   end
 end

activerecord/test/cases/tasks/mysql_rake_test.rb

@@ -318,6 +318,28 @@ if current_adapter?(:Mysql2Adapter)
         end
       end
 
+      def test_structure_dump_with_hash_extra_flags_for_a_different_driver
+        filename = "awesome-file.sql"
+        expected_command = ["mysqldump", "--result-file", filename, "--no-data", "--routines", "--skip-comments", "test-db"]
+
+        assert_called_with(Kernel, :system, expected_command, returns: true) do
+          with_structure_dump_flags({ postgresql: ["--noop"] }) do
+            ActiveRecord::Tasks::DatabaseTasks.structure_dump(@configuration, filename)
+          end
+        end
+      end
+
+      def test_structure_dump_with_hash_extra_flags_for_the_correct_driver
+        filename = "awesome-file.sql"
+        expected_command = ["mysqldump", "--noop", "--result-file", filename, "--no-data", "--routines", "--skip-comments", "test-db"]
+
+        assert_called_with(Kernel, :system, expected_command, returns: true) do
+          with_structure_dump_flags({ mysql2: ["--noop"] }) do
+            ActiveRecord::Tasks::DatabaseTasks.structure_dump(@configuration, filename)
+          end
+        end
+      end
+
       def test_structure_dump_with_ignore_tables
         filename = "awesome-file.sql"
         ActiveRecord::SchemaDumper.stub(:ignore_tables, ["foo", "bar"]) do
@@ -404,6 +426,28 @@ if current_adapter?(:Mysql2Adapter)
         end
       end
 
+      def test_structure_load_with_hash_extra_flags_for_a_different_driver
+        filename = "awesome-file.sql"
+        expected_command = ["mysql", "--execute", %{SET FOREIGN_KEY_CHECKS = 0; SOURCE #{filename}; SET FOREIGN_KEY_CHECKS = 1}, "--database", "test-db"]
+
+        assert_called_with(Kernel, :system, expected_command, returns: true) do
+          with_structure_load_flags({ postgresql: ["--noop"] }) do
+            ActiveRecord::Tasks::DatabaseTasks.structure_load(@configuration, filename)
+          end
+        end
+      end
+
+      def test_structure_load_with_hash_extra_flags_for_the_correct_driver
+        filename = "awesome-file.sql"
+        expected_command = ["mysql", "--noop", "--execute", %{SET FOREIGN_KEY_CHECKS = 0; SOURCE #{filename}; SET FOREIGN_KEY_CHECKS = 1}, "--database", "test-db"]
+
+        assert_called_with(Kernel, :system, expected_command, returns: true) do
+          with_structure_load_flags({ mysql2: ["--noop"] }) do
+            ActiveRecord::Tasks::DatabaseTasks.structure_load(@configuration, filename)
+          end
+        end
+      end
+
       private
         def with_structure_load_flags(flags)
           old = ActiveRecord::Tasks::DatabaseTasks.structure_load_flags

activerecord/test/cases/tasks/postgresql_rake_test.rb

@@ -387,6 +387,26 @@ if current_adapter?(:PostgreSQLAdapter)
         end
       end
 
+      def test_structure_dump_with_hash_extra_flags_for_a_different_driver
+        expected_command = ["pg_dump", "--schema-only", "--no-privileges", "--no-owner", "--file", @filename, "my-app-db"]
+
+        assert_called_with(Kernel, :system, expected_command, returns: true) do
+          with_structure_dump_flags({ mysql2: ["--noop"] }) do
+            ActiveRecord::Tasks::DatabaseTasks.structure_dump(@configuration, @filename)
+          end
+        end
+      end
+
+      def test_structure_dump_with_hash_extra_flags_for_the_correct_driver
+        expected_command = ["pg_dump", "--schema-only", "--no-privileges", "--no-owner", "--file", @filename, "--noop", "my-app-db"]
+
+        assert_called_with(Kernel, :system, expected_command, returns: true) do
+          with_structure_dump_flags({ postgresql: ["--noop"] }) do
+            ActiveRecord::Tasks::DatabaseTasks.structure_dump(@configuration, @filename)
+          end
+        end
+      end
+
       def test_structure_dump_with_ignore_tables
         assert_called(
           ActiveRecord::SchemaDumper,
@@ -509,6 +529,28 @@ if current_adapter?(:PostgreSQLAdapter)
         end
       end
 
+      def test_structure_load_with_hash_extra_flags_for_a_different_driver
+        filename = "awesome-file.sql"
+        expected_command = ["psql", "--set", "ON_ERROR_STOP=1", "--quiet", "--no-psqlrc", "--file", filename, @configuration["database"]]
+
+        assert_called_with(Kernel, :system, expected_command, returns: true) do
+          with_structure_load_flags({ mysql2: ["--noop"] }) do
+            ActiveRecord::Tasks::DatabaseTasks.structure_load(@configuration, filename)
+          end
+        end
+      end
+
+      def test_structure_load_with_hash_extra_flags_for_the_correct_driver
+        filename = "awesome-file.sql"
+        expected_command = ["psql", "--set", "ON_ERROR_STOP=1", "--quiet", "--no-psqlrc", "--file", filename, "--noop", @configuration["database"]]
+
+        assert_called_with(Kernel, :system, expected_command, returns: true) do
+          with_structure_load_flags({ postgresql: ["--noop"] }) do
+            ActiveRecord::Tasks::DatabaseTasks.structure_load(@configuration, filename)
+          end
+        end
+      end
+
       def test_structure_load_accepts_path_with_spaces
         filename = "awesome file.sql"
         assert_called_with(