hello there all. i have a question about how to set up a relationship thru another table that i am using as kind of a pointer. it works like this. i have machines each machine has_many: machine_options machine_options table has an `id`, `option_description`, and `sensor` i also have several other tables for each type of sensor for example `pressure_sensors`, `volt_sensors`, `flow_sensors` etc.. each of these tables has a `monitor` that will match the `monitor` in one of the type of machine_option like this machine 3 has a 2 options so the rows for machine_options may look like this `machine_id` = ''3'', `option_description` = ''pressure'', `monitor` ''23psi343'' `machine_id` = ''3'', `option_description` = ''volts'', `monitor` ''234vdc43'' so here is the part where i am stumped. is there a way i can set up something that allows me to conditionally link a table? like IF `option_description` == ''pressure'' then machine ''3'' has_one :pressure_sensor find by monitor = machine_option.monitor Or if not, what would be a good suggestion of a way i could map this out. or have a way to return a pressure_sensor object for a machine with an `option_description` that == ''pressure'' the last point that i think will not be a problem is each `pressure_sensor` has an `id`. There is another table of `pressure_sensor_records` that records the history of reports from these sensors. it is set up like this: `pressure_sensor_records` belongs_to `pressure_sensors` `id`, `pressure_sensor_id`, `datetime`, `value` so i could have pressure_sensor has_many :pressure_sensor_reports that part i think will not be a problem. if you have read this far, thanks for your time. does this challenge make sense? thanks sk --~--~---------~--~----~------------~-------~--~----~ You received this message because you are subscribed to the Google Groups "Ruby on Rails: Talk" group. To post to this group, send email to rubyonrails-talk-/JYPxA39Uh5TLH3MbocFFw@public.gmane.org To unsubscribe from this group, send email to rubyonrails-talk-unsubscribe-/JYPxA39Uh5TLH3MbocFFw@public.gmane.org For more options, visit this group at http://groups.google.com/group/rubyonrails-talk?hl=en -~----------~----~----~----~------~----~------~--~---