Is it possible to call a MySQL stored procedure from Ruby?

Question

When I try to call a stored procedure from Rails, I get this exception:

ActiveRecord::StatementInvalid: Mysql::Error: PROCEDURE pipeline-ws_development.match_save_all can't return a result set in the given context: call match_save_all()
    from /Users/otto/Projects/Futures/src/pipeline-ws/vendor/rails/activerecord/lib/active_record/connection_adapters/abstract_adapter.rb:150:in `log'
    from /Users/otto/Projects/Futures/src/pipeline-ws/vendor/rails/activerecord/lib/active_record/connection_adapters/mysql_adapter.rb:281:in `execute'
    from (irb):3

There is a page in the Rails Wiki that discusses a patch for the MySQL adapter that resolves this issue, but it's out-of-date and doesn't seem to work anymore.

The configuration code enables stored procedures correctly, but it still has the issue with the connection getting out of sync after a stored procedure call and the new call_sp method doesn't work anymore.

Any suggestions for how to get this working?

This is the code I'm using:

ActiveRecord::Base.connection("call storedproc()")

It throws the same exception whether storedproc() returns any results or not.

Answer 1

Would it work to wrap the procedure in a function? If Ruby's barfing due to no rows returned (...can't return a result set in the given context...), this may fix it:

DELIMITER $

CREATE PROCEDURE tProc()
BEGIN
    SET @a = 'test';
END;
$

CREATE FUNCTION tFunc()
RETURNS INT
BEGIN
    CALL tProc();
    RETURN 1;
END;
$

DELIMITER ;

SELECT tFunc() FROM DUAL;
>> 1

SELECT @a FROM DUAL;
>> 'test'

Although, realistically, this isn't a very extensible solution.

Followup: I'm pretty n00by at Ruby/ActiveRecord, but this example definitely works

ActiveRecord::Base.establish_connection(authopts)

class TestClass < ActiveRecord::Base
end

test_class = TestClass.new
puts %{#{test_class.connection.select_one('SELECT tFunc() AS tf FROM DUAL')}}
>> tf1

Using CALL tProc() resulted in an error similar to yours.

Answer 2

Are you using ActiveRecord::Base.connection.execute? This method should allow you to execute some arbitrary SQL statement that isn't naively supported in the Active Record wrapper.

Answer 3

I've submitted a patch to Rails 2.3.4 which gives a configuration option to fix this problem. Please stop by my ticket and show your support for it!

https://rails.lighthouseapp.com/projects/8994/tickets/3151-mysql-adapter-update-to-enable-use-of-stored-procedures