Load database adapters on demand. Eliminates config.connection_adapters and RAILS_CONNECTION_ADAPTERS. Closes #8456.

git-svn-id: http://svn-commit.rubyonrails.org/rails/trunk@6833 5ecf4fe2-1ee6-0310-87b1-e25e094e27de

1 files changed, 6 insertions, 1 deletions

diff --git a/activerecord/lib/active_record/connection_adapters/abstract/connection_specification.rb b/activerecord/lib/active_record/connection_adapters/abstract/connection_specification.rb
index 1a76050872..918c29114c 100644
--- a/activerecord/lib/active_record/connection_adapters/abstract/connection_specification.rb
+++ b/activerecord/lib/active_record/connection_adapters/abstract/connection_specification.rb
@@ -207,7 +207,12 @@ module ActiveRecord
           spec = spec.symbolize_keys
           unless spec.key?(:adapter) then raise AdapterNotSpecified, "database configuration does not specify adapter" end
           adapter_method = "#{spec[:adapter]}_connection"
-          unless respond_to?(adapter_method) then raise AdapterNotFound, "database configuration specifies nonexistent #{spec[:adapter]} adapter" end
+
+          require "active_record/connection_adapters/#{spec[:adapter]}_adapter"
+          unless respond_to?(adapter_method)
+            raise AdapterNotFound, "database configuration specifies nonexistent #{spec[:adapter]} adapter"
+          end
+
           remove_connection
           establish_connection(ConnectionSpecification.new(spec, adapter_method))
       end