Only build a ConnectionSpecification if required

Gemfile

@@ -36,9 +36,9 @@ group :test do
     gem 'ruby-prof', '~> 0.11.2'
   end
 
-  platforms :mri_19, :mri_20 do
-    gem 'debugger'
-  end
+  # platforms :mri_19, :mri_20 do
+  #   gem 'debugger'
+  # end
 
   gem 'benchmark-ips'
 end

activerecord/lib/active_record/connection_adapters/connection_specification.rb

@@ -32,6 +32,24 @@ module ActiveRecord
           end
         end
 
+        def spec(config)
+          spec = resolve(config).symbolize_keys
+
+          raise(AdapterNotSpecified, "database configuration does not specify adapter") unless spec.key?(:adapter)
+
+          path_to_adapter = "active_record/connection_adapters/#{spec[:adapter]}_adapter"
+          begin
+            require path_to_adapter
+          rescue Gem::LoadError => e
+            raise Gem::LoadError, "Specified '#{spec[:adapter]}' for database adapter, but the gem is not loaded. Add `gem '#{e.name}'` to your Gemfile (and ensure its version is at the minimum required by ActiveRecord)."
+          rescue LoadError => e
+            raise LoadError, "Could not load '#{path_to_adapter}'. Make sure that the adapter in config/database.yml is valid. If you use an adapter other than 'mysql', 'mysql2', 'postgresql' or 'sqlite3' add the necessary adapter gem to the Gemfile.", e.backtrace
+          end
+
+          adapter_method = "#{spec[:adapter]}_connection"
+          ConnectionSpecification.new(spec, adapter_method)
+        end
+
         private
 
         def resolve_connection(spec) #:nodoc:
@@ -52,30 +70,15 @@ module ActiveRecord
             resolve_string_connection(spec) if spec.is_a?(String)
           end
           raise(AdapterNotSpecified, "#{spec} database is not configured") unless config
-          resolve_connection config
+          resolve_connection(config)
         end
 
         def resolve_hash_connection(spec) # :nodoc:
-          spec = spec.symbolize_keys
-
-          raise(AdapterNotSpecified, "database configuration does not specify adapter") unless spec.key?(:adapter)
-
-          path_to_adapter = "active_record/connection_adapters/#{spec[:adapter]}_adapter"
-          begin
-            require path_to_adapter
-          rescue Gem::LoadError => e
-            raise Gem::LoadError, "Specified '#{spec[:adapter]}' for database adapter, but the gem is not loaded. Add `gem '#{e.name}'` to your Gemfile (and ensure its version is at the minimum required by ActiveRecord)."
-          rescue LoadError => e
-            raise LoadError, "Could not load '#{path_to_adapter}'. Make sure that the adapter in config/database.yml is valid. If you use an adapter other than 'mysql', 'mysql2', 'postgresql' or 'sqlite3' add the necessary adapter gem to the Gemfile.", e.backtrace
-          end
-
-          adapter_method = "#{spec[:adapter]}_connection"
-
-          ConnectionSpecification.new(spec, adapter_method)
+          spec
         end
 
         def resolve_string_connection(spec) # :nodoc:
-          config = URI.parse spec
+          config  = URI.parse spec
           adapter = config.scheme
           adapter = "postgresql" if adapter == "postgres"
 
@@ -89,12 +92,12 @@ module ActiveRecord
                        config.path.sub(%r{^/},"")
                      end
 
-          spec = { :adapter  => adapter,
-                   :username => config.user,
-                   :password => config.password,
-                   :port     => config.port,
-                   :database => database,
-                   :host     => config.host }
+          spec = { "adapter"  => adapter,
+                   "username" => config.user,
+                   "password" => config.password,
+                   "port"     => config.port,
+                   "database" => database,
+                   "host"     => config.host }
 
           spec.reject!{ |_,value| value.blank? }
 
@@ -103,8 +106,7 @@ module ActiveRecord
           spec.map { |key,value| spec[key] = uri_parser.unescape(value) if value.is_a?(String) }
 
           if config.query
-            options = Hash[config.query.split("&").map{ |pair| pair.split("=") }].symbolize_keys
-
+            options = Hash[config.query.split("&").map{ |pair| pair.split("=") }]
             spec.merge!(options)
           end
 

activerecord/lib/active_record/connection_handling.rb

@@ -36,7 +36,7 @@ module ActiveRecord
     # may be returned on an error.
     def establish_connection(spec = ENV["DATABASE_URL"])
       resolver = ConnectionAdapters::ConnectionSpecification::Resolver.new configurations
-      spec = resolver.resolve(spec)
+      spec = resolver.spec(spec)
 
       unless respond_to?(spec.adapter_method)
         raise AdapterNotFound, "database configuration specifies nonexistent #{spec.config[:adapter]} adapter"

activerecord/lib/active_record/railtie.rb

@@ -56,7 +56,7 @@ module ActiveRecord
           resolver = ActiveRecord::ConnectionAdapters::ConnectionSpecification::Resolver.new(configuration)
 
           configuration.each do |key, value|
-            configuration[key] = resolver.resolve(value).config.stringify_keys if value
+            configuration[key] = resolver.resolve(value) if value
           end
 
           ActiveRecord::Tasks::DatabaseTasks.database_configuration = configuration

activerecord/test/cases/connection_specification/resolver_test.rb

@@ -5,13 +5,19 @@ module ActiveRecord
     class ConnectionSpecification
       class ResolverTest < ActiveRecord::TestCase
         def resolve(spec, config={})
-          Resolver.new(config).resolve(spec).config
+          Resolver.new(config).resolve(spec)
+        end
+
+        def spec(spec, config={})
+          Resolver.new(config).spec(spec)
         end
 
         def test_url_invalid_adapter
-          assert_raises(LoadError) do
-            resolve 'ridiculous://foo?encoding=utf8'
+          error = assert_raises(LoadError) do
+            spec 'ridiculous://foo?encoding=utf8'
           end
+
+          assert_match "Could not load 'active_record/connection_adapters/ridiculous_adapter'", error.message
         end
 
         # The abstract adapter is used simply to bypass the bit of code that
@@ -20,60 +26,52 @@ module ActiveRecord
         def test_url_from_environment
           spec = resolve :production, 'production' => 'abstract://foo?encoding=utf8'
           assert_equal({
-            adapter:  "abstract",
-            host:     "foo",
-            encoding: "utf8" }, spec)
+            "adapter"  =>  "abstract",
+            "host"     =>  "foo",
+            "encoding" => "utf8" }, spec)
         end
 
         def test_url_host_no_db
           spec = resolve 'abstract://foo?encoding=utf8'
           assert_equal({
-            adapter:  "abstract",
-            host:     "foo",
-            encoding: "utf8" }, spec)
+            "adapter"  => "abstract",
+            "host"     => "foo",
+            "encoding" => "utf8" }, spec)
         end
 
         def test_url_host_db
           spec = resolve 'abstract://foo/bar?encoding=utf8'
           assert_equal({
-            adapter:  "abstract",
-            database: "bar",
-            host:     "foo",
-            encoding: "utf8" }, spec)
+            "adapter"  => "abstract",
+            "database" => "bar",
+            "host"     => "foo",
+            "encoding" => "utf8" }, spec)
         end
 
         def test_url_port
           spec = resolve 'abstract://foo:123?encoding=utf8'
           assert_equal({
-            adapter:  "abstract",
-            port:     123,
-            host:     "foo",
-            encoding: "utf8" }, spec)
+            "adapter"  => "abstract",
+            "port"     => 123,
+            "host"     => "foo",
+            "encoding" => "utf8" }, spec)
         end
 
         def test_encoded_password
           password = 'am@z1ng_p@ssw0rd#!'
           encoded_password = URI.encode_www_form_component(password)
           spec = resolve "abstract://foo:#{encoded_password}@localhost/bar"
-          assert_equal password, spec[:password]
-        end
-
-        def test_descriptive_error_message_when_adapter_is_missing
-          error = assert_raise(LoadError) do
-            resolve(adapter: 'non-existing')
-          end
-
-          assert_match "Could not load 'active_record/connection_adapters/non-existing_adapter'", error.message
+          assert_equal password, spec["password"]
         end
 
         def test_url_host_db_for_sqlite3
           spec = resolve 'sqlite3://foo:bar@dburl:9000/foo_test'
-          assert_equal('/foo_test', spec[:database])
+          assert_equal('/foo_test', spec["database"])
         end
 
         def test_url_host_memory_db_for_sqlite3
           spec = resolve 'sqlite3://foo:bar@dburl:9000/:memory:'
-          assert_equal(':memory:', spec[:database])
+          assert_equal(':memory:', spec["database"])
         end
       end
     end

railties/lib/rails/commands/dbconsole.rb

@@ -84,7 +84,7 @@ module Rails
         require APP_PATH
         ActiveRecord::ConnectionAdapters::ConnectionSpecification::Resolver.new(
           Rails.application.config.database_configuration || {}
-        ).resolve(ENV["DATABASE_URL"]).config.stringify_keys
+        ).resolve(ENV["DATABASE_URL"])
       end
     end