如何从Rails调用MySQL存储过程？

Question

A simple stored procedure in MySQL:

CREATE PROCEDURE `proc01`()
BEGIN
 SELECT * FROM users;
END

Starts Rails console:

$ script/console
Loading development environment (Rails 2.3.5)
>> User.connection.execute("CALL proc01")
=> #<Mysql::Result:0x10343efa0>

Looks good. BUT, any more call to the same stored procedure via the existing connection will result in an Commands out of sync error:

>> User.connection.execute("CALL proc01")
ActiveRecord::StatementInvalid: Mysql::Error: Commands out of sync; you can't run this command now: CALL proc01
    from /Library/Ruby/Gems/1.8/gems/activerecord-2.3.5/lib/active_record/connection_adapters/abstract_adapter.rb:219:in `log'
    from /Library/Ruby/Gems/1.8/gems/activerecord-2.3.5/lib/active_record/connection_adapters/mysql_adapter.rb:323:in `execute'
    from (irb):2

The error can be cleared by a "reload!" command in the console:

>> reload!
Reloading...
=> true
>> User.connection.execute("CALL proc01")
=> #<Mysql::Result:0x1033f14d0>
>> 

How can I call MySQL stored procedure from Rails?

Answer 1

EDIT:

--

Using ActiveRecord::Base.connections.exec_query() is as far as I can tell a MUCH better approach just because it returns an array of hashes as one would expect, which ActiveRecord::Base.connections.execute does not.

Documentation

--

Please read the edit above, I'm leaving the below for reference.

While I realise this question is quite old and because the links ohho posted have 404'd, I had this same error recently.

I was able to fix it by doing the following:

result = ActiveRecord::Base.connection.execute("call example_proc()") ActiveRecord::Base.clear_active_connections!

Once you've cleared connections, you can run any other queries where as before it would have failed on trying to access the database through rails or another stored proc.

http://apidock.com/rails/v3.2.13/ActiveRecord/Base/clear_active_connections%21/class

-- EDIT:

It's also worth mentioning that one shouldn't store the ActiveRecord connection in a variable as per leente's post on this link

"Don't cache it!

Don't store a connection in a variable, because another thread might try to use it when it's already checked back in into the connection pool. See: ConnectionPool "

connection = ActiveRecord::Base.connection   #WRONG

threads = (1..100).map do
 Thread.new do
begin
  10.times do
    connection.execute("SELECT SLEEP(1)")  # WRONG
    ActiveRecord::Base.connection.execute("SELECT SLEEP(1)")  # CORRECT
  end
  puts "success"
rescue => e
  puts e.message
   end
  end
end

threads.each(&:join)