From b7cc1eb658dbc0569a9a43c7bf6a89c18d934837 Mon Sep 17 00:00:00 2001 From: eileencodes Date: Fri, 5 Apr 2019 12:09:15 -0400 Subject: Ensure a handler is set when using `connected_to` After looking at #35800 there is definitely an issue in the `connected_to` method although it's generally behaving. Here are the details: 1) I added a default connection role - writing - to the connection handler lookup. I did this because otherwise if you did this: ``` connected_to(databse: :development) ``` And development wasn't a pre-established role it would create a new handler and connect using that. I don't think this is right so I've updated it to pick up the default (:writing) unless otherwise specified. To set a handler when using the database version pass a hash like you would to `connects_to`: ``` connected_to(database: { readonly_slow: :development }) ``` This will connect the `development` database to the `readonly_slow` handler/role. 2) I updated the tests to match this behavior that we expect. 3) I updated the documentation to clarify that using `connected_to` with a `database` key will establish a new connection every time. This is exactly how `establish_connection` behaves and I feel this is correct. If you want to only establish a connection once you should do that in the model with `connects_to` and then swap on the role instead of on the database hash/key. 4) In regards to #35800 this fixes the case where you pass a symbol to the db and not a hash. But it doesn't fix a case where you may pass an unknown handler to an abstract class that's not connected. This is tricky because technical AbstractFoo doesn't have any connections except for through ApplicationRecord, so in the case of the application that was shared we should only be swapping connections on ActiveRecord::Base because there are no other actual connections - AbstractFoo isn't needed since it's not establishing a new connection. If we need AbstractFoo to connect to a new handler we should establish that connection with the handler in AbstractFoo before trying to shard there. --- .../lib/active_record/connection_handling.rb | 27 ++++++++++++++-------- 1 file changed, 17 insertions(+), 10 deletions(-) (limited to 'activerecord/lib') diff --git a/activerecord/lib/active_record/connection_handling.rb b/activerecord/lib/active_record/connection_handling.rb index 53069cd899..6782833c5a 100644 --- a/activerecord/lib/active_record/connection_handling.rb +++ b/activerecord/lib/active_record/connection_handling.rb @@ -85,14 +85,14 @@ module ActiveRecord # based on the requested role: # # ActiveRecord::Base.connected_to(role: :writing) do - # Dog.create! # creates dog using dog connection + # Dog.create! # creates dog using dog writing connection # end # # ActiveRecord::Base.connected_to(role: :reading) do # Dog.create! # throws exception because we're on a replica # end # - # ActiveRecord::Base.connected_to(role: :unknown_ode) do + # ActiveRecord::Base.connected_to(role: :unknown_role) do # # raises exception due to non-existent role # end # @@ -100,11 +100,20 @@ module ActiveRecord # you can use +connected_to+ with a +database+ argument. The +database+ argument # expects a symbol that corresponds to the database key in your config. # - # This will connect to a new database for the queries inside the block. - # # ActiveRecord::Base.connected_to(database: :animals_slow_replica) do # Dog.run_a_long_query # runs a long query while connected to the +animals_slow_replica+ # end + # + # This will connect to a new database for the queries inside the block. By + # default the `:writing` role will be used since all connections must be assigned + # a role. If you would like to use a different role you can pass a hash to database: + # + # ActiveRecord::Base.connected_to(database: { readonly_slow: :animals_slow_replica }) do + # Dog.run_a_long_query # runs a long query while connected to the +animals_slow_replica+ + # using the readonly_slow role. + # end + # + # When using the database key a new connection will be established every time. def connected_to(database: nil, role: nil, &blk) if database && role raise ArgumentError, "connected_to can only accept a `database` or a `role` argument, but not both arguments." @@ -112,17 +121,14 @@ module ActiveRecord if database.is_a?(Hash) role, database = database.first role = role.to_sym - else - role = database.to_sym end config_hash = resolve_config_for_connection(database) handler = lookup_connection_handler(role) - with_handler(role) do - handler.establish_connection(config_hash) - yield - end + handler.establish_connection(config_hash) + + with_handler(role, &blk) elsif role with_handler(role.to_sym, &blk) else @@ -154,6 +160,7 @@ module ActiveRecord end def lookup_connection_handler(handler_key) # :nodoc: + handler_key ||= ActiveRecord::Base.writing_role connection_handlers[handler_key] ||= ActiveRecord::ConnectionAdapters::ConnectionHandler.new end -- cgit v1.2.3