On Feb 9, 8:50 pm, John Firebaugh <[email protected]> wrote:
> On Wed, Feb 9, 2011 at 6:33 PM, Jeremy Evans <[email protected]> wrote:
> > I was planning on adding the feature as a plugin before 3.21.0. It's
> > fairly simple. Use an anonymous module for each class, and for every
> > many_to_one call, add the foreign key setter method to the anonymous
> > module to clear the association cache for the association if the value
> > has changed (calling super in either case). That way you can just do
> > "Sequel::Model.plugin :stale_associations" before defining your models
> > and automatically get the behavior.
>
> > Anyone who wants to implement it first is welcome to submit a patch/
> > pull request. :)
>
> I'm working on it.
>
> Any given column can act as a foreign key for more than one association
> though. Given that, do you still think that the logic should be in the
> setter method? It would have to iterate over all associations that use that
> column. I think it might be easier to overload the association accessor.
Overloading the accessor slows down all accesses, which I assume are
much more frequent than setters. It is true that you have to handle
all associations that depend on the foreign key, but that shouldn't be
too difficult (completely untested code):
# Class instance variables
@stale_associations = {}
include(@stale_associations_module = Module.new)
# for each many_to_one association definition
reflection[:keys].each do |k|
assocs = (@stale_associations[k] ||= [])
assocs << reflection[:name]
@stale_associations_module.class_eval do
unless method_defined?("#{k}=")
define_method("#{k}=") do |v|
super(v)
assocs.each{|a| associations.delete(a)}
end
end
end
end
Look at the lazy_attributes plugin for a similar idea that uses an
anonymous module.
Jeremy
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