DRY up help using #method

Rails
1

I am a newbie trying to DRY up my first application. Going well accept
this annoying item (simplified down to problematic code) …

Original code:

business_attributes = params[…] # values from a form in a view
business_application = BusinessApplication.find(…) # id from view
business_area = BusinessArea.create! business_attributes
business_application.business_areas << business_area unless
business_application.nil?
business_application.save

Now refactored to make more generic and not tied to any particular
models (so I can add as an ApplicationController method and become part
of a acts_as helper). This code is part of a set of methods that are
used 10’s of times across various controllers (the rest successfully
DRY’d). target and source have a habtm relationship. The new code is as
follows:

target_model_class = Object.const_get(target) # target ==
‘business_areas’ - passed as argument
source_model_class = Object.const_get(source) # source ==
‘business_applications’ - passed as argument

attributes = params[…] # values from a form in a view
source_instance = source_model_class.find(…) # id from view
target_instance = target_model_class.create! attributes
source_instance.method(target) << target_instance unless
source_instance.nil?
source_instance.save

But gets the following error complaining << method does not exist:

undefined method `<<’ for #<Method:
BusinessApplication#business_areas>

Have tried using #push instead of << method but with same error. Also
tried some poorly constructed #call methods too. I know I’m probably
doing something completely wrong around the use of #method.

Any help?

Thanks!

Martyn.

2

Martyn:

source_instance.save

But gets the following error complaining << method does not exist:

undefined method `<<’ for #<Method:
BusinessApplication#business_areas>

You don’t need to use #method method : you don’t want to
manipulate a Method object but you just want to send a message
whose name is an association.

You should look at : source_instance.send(target)

– Jean-François.

3

Jean-Fran�ois,

Thank you. That was it.

Martyn.