Rails - ActiveRecord get database name from an Instance

Question

I have a model distributed into many databases. Here is an example:

class Timetablerange < ActiveRecord::Base
  self.table_name = "TimetableRange"

  def self.integration(integration)
    self.establish_connection(integration.to_sym)
    return self
  end

end

So when I want to fetch an instance from one database:

Timetablerange.integration(:integration_id).find(1)

I need to get the database_name from an instance without using:

Timetable.connection.current_database

Since it can be different if I use this:

instance_a = Timetablerange.integration(:integration_1).find(1)
instance_b = Timetablerange.integration(:integration_2).find(1)

At this time Timetable.connection.current_database = :integration_2 but instance_a was loaded from :integration_1.

I've tried to use:

instance_a.connection_handler.connection_pools

And it lists all the connections. But how can I now witch database was instance_a loaded from?

Thanks so much for the help!

AFAIK instances have no memory of which connection they were retrieved from — Frederick Cheung, Jul 18 '14 at 15:24
If you are right, then when I call .save in the instance ActiveRecord could update the values in an arbitrary database? That sounds risky! — dolarsrg, Jul 21 '14 at 07:35
I believe so yes - if you are switching db connections around a lot that would be a hazard — Frederick Cheung, Jul 21 '14 at 09:04
Ok! Thanks so much then! I might add some constructor for each instance to save in an attr_accessor the connection. Best regards! — dolarsrg, Jul 23 '14 at 07:26

score 0 · Accepted Answer · answered Feb 10 '16 at 18:53

0

If you are using mysql you probably can use:

Timetable.connection.execute("select database()").first.first

The other databases might have a query to get the current db too.

answered Feb 10 '16 at 18:53

Arthur Neves

11,840
8
60
73

Rails - ActiveRecord get database name from an Instance

1 Answers1