How can I make an aggregated property support ActiveRecord::Dirty semantics?

Rails
1

Hoping one of the many experts here might help out a newb…

I have an aggregated attribute which I want to be able ask about its
_changed? ness, etc.

composed_of :range,
:class_name => ‘Range’,
:mapping => [ %w(range_begin begin), %w(range_end end)],
:allow_nil => true

If I use the aggregation:

foo.range = 1…10

This is what I get:

foo.range # => 1…10
foo.range_changed? # NoMethodError
foo.range_was # ditto
foo.changed # [‘range_begin’, ‘range_end’]

So basically, I’m not getting ActiveRecord::Dirty semantics on
aggregated attributes (they are on the underlying db attrs).

Is there a beautiful way to implement dirty semantics on the
aggregation? I’m not having a lot of luck with
alias_attribute_with_dirty, etc. I really am unfond of making my own
range_changed?, range_was, etc. Frankly, I was a bit surprised that
aggregation didn’t support dirty natively…

Advice greatly appreciated.

2

On Nov 6, 12:51 pm, Eric H. [email protected] wrote:

So basically, I’m not getting ActiveRecord::Dirty semantics on aggregated attributes (they are on the underlying db attrs).

Is there a beautiful way to implement dirty semantics on the aggregation? I’m not having a lot of luck with alias_attribute_with_dirty, etc. I really am unfond of making my own range_changed?, range_was, etc. Frankly, I was a bit surprised that aggregation didn’t support dirty natively…

The dirty stuff is all centred around actual attributes. you could
define

def range_changed?
range_begin_changed? || range_end_changed
end

def range_was
range_begin … range_end
end

and so on. shouldn’t be too hard to automate definition of these
methods.

Fred