On Jan 27, 9:16 pm, bob <larr...@gmail.com> wrote:
> This general idea, of reconstituting a model from it's YAML
> representation works in some of my projects, but not in any new
> ones.
>
> I have no idea why this would be the case.
>
At a guess it looks like during the yaml loading process it calls (or
causes to be called) respond_to?, however respond_to for an AR object
depends on the internal state (because of the dynamically generated
methods) of the object, and respond_to is being called when that state
is inconsistent (I'd guess that @attributes hasn't been restored yet,
so is nil). Changing Dummy to ActiveRecord:Dummy changes things
because yaml no longer finds your class and so it doesn't get AR's
respond_to (what you change it to is probably irrelevant, as long as
you don't change it to some other AR class. I seem to recall that
historically, although method_missing etc was overriden to add dynamic
methods, respond_to wasn't, which didn't make AR a very good citizen,
which may be why this works with projects using old versions of rails
Fred
> Changing the type of the yaml dump from
> !ruby/object:Dummy
> to
> !ruby/ActiveRecord:Dummy
> helps a little bit, but still returns something weird.
>
> ruby-1.9.2-p0 > tom
> => "--- !ruby/object:Dummy \nattributes: \n id: 1\n name: Tim\n
> created_at: 2011-01-27 21:12:33.327345\n updated_at: 2011-01-27
> 21:12:33.327345\nattributes_cache: {}\n\nchanged_attributes: {}\n
> \ndestroyed: false\nmarked_for_destruction: false\npersisted: true
> \npreviously_changed: {}\n\nreadonly: false\n"
> ruby-1.9.2-p0 > bill = tom.gsub("object", 'ActiveRecord')
> => "--- !ruby/ActiveRecord:Dummy \nattributes: \n id: 1\n name: Tim
> \n created_at: 2011-01-27 21:12:33.327345\n updated_at: 2011-01-27
> 21:12:33.327345\nattributes_cache: {}\n\nchanged_attributes: {}\n
> \ndestroyed: false\nmarked_for_destruction: false\npersisted: true
> \npreviously_changed: {}\n\nreadonly: false\n"
> ruby-1.9.2-p0 > YAML.load(bill)
> => #<Syck::DomainType:0x00000100c634b8 @domain="ruby.yaml.org,2002",
> @type_id="ActiveRecord:Dummy", @value={"attributes"=>{"id"=>1,
> "name"=>"Tim", "created_at"=>"2011-01-27 21:12:33.327345",
> "updated_at"=>"2011-01-27 21:12:33.327345"}, "attributes_cache"=>{},
> "changed_attributes"=>{}, "destroyed"=>false,
> "marked_for_destruction"=>false, "persisted"=>true,
> "previously_changed"=>{}, "readonly"=>false}>
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