Refactored abstract MySQL adapter to support lazy version check.

Will allow sub classes to override the protected
`#check_version` method hook if desired.

For example, this will be most helpful in sub classes that wish
to support lazy initialization because the version check can
be postponed until the connection is ready to be initialized.

1 files changed, 11 insertions, 4 deletions

diff --git a/activerecord/lib/active_record/connection_adapters/abstract_mysql_adapter.rb b/activerecord/lib/active_record/connection_adapters/abstract_mysql_adapter.rb
index d40f38fb77..5ad3fdbb88 100644
--- a/activerecord/lib/active_record/connection_adapters/abstract_mysql_adapter.rb
+++ b/activerecord/lib/active_record/connection_adapters/abstract_mysql_adapter.rb
@@ -26,6 +26,7 @@ module ActiveRecord
       #   ActiveRecord::ConnectionAdapters::Mysql2Adapter.emulate_booleans = false
       class_attribute :emulate_booleans, default: true
 
+      SUPPORTED_VERSION = "5.5.8"
       NATIVE_DATABASE_TYPES = {
         primary_key: "bigint auto_increment PRIMARY KEY",
         string:      { name: "varchar", limit: 255 },
@@ -54,10 +55,7 @@ module ActiveRecord
         super(connection, logger, config)
 
         @statements = StatementPool.new(self.class.type_cast_config_to_integer(config[:statement_limit]))
-
-        if version < "5.5.8"
-          raise "Your version of MySQL (#{version_string}) is too old. Active Record supports MySQL >= 5.5.8."
-        end
+        check_version
       end
 
       def version #:nodoc:
@@ -534,6 +532,15 @@ module ActiveRecord
         end
       end
 
+      protected
+
+        def check_version
+          if version < SUPPORTED_VERSION
+            raise "Your version of MySQL (#{version_string}) is too old. Active Record supports " \
+                  "MySQL >= #{SUPPORTED_VERSION}."
+          end
+        end
+
       private
         def combine_multi_statements(total_sql)
           total_sql.each_with_object([]) do |sql, total_sql_chunks|