In the following ActiveRecord code, it defines a method to access
associations like user.addresses (has_many)
def collection_reader_method(reflection,
association_proxy_class)
define_method(reflection.name) do |*params|
force_reload = params.first unless params.empty?
association = instance_variable_get("@#{reflection.name}")
unless association.respond_to?(:loaded?)
association = association_proxy_class.new(self,
reflection)
instance_variable_set("@#{reflection.name}",
association)
end
association.reload if force_reload
association
end
end
What is so weird is that association_proxy_class.new(self, reflection)
returns an object of type Array for a has_many, yet, if you look in
HasManyAssociation, at the initialize method, it is :
def initialize(owner, reflection)
super
construct_sql
end
which returns a Sql String. How the heck does it instantiate an array?
And then how does that array have all the active record methods on it,
like being able to do book.pages.find(:first). After all, the return
object is of type Array, not some class that extends Array and includes
those methods.
What am I missing here?
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On 3 Nov 2007, at 20:27, Aryk Grosz wrote:> which returns a Sql String. How the heck does it instantiate an array? > And then how does that array have all the active record methods on it, > like being able to do book.pages.find(:first). After all, the return > object is of type Array, not some class that extends Array and > includes > those methods. >say you have User, User has_many :addresses. User.addresses is not an array. It looks like an array, it quacks like an array but it''s actually an association proxy pretending to be an array. It manages an actual array with the elements of the collection and (via method_missing) lets that array handle most calls. Fred
Frederick Cheung wrote:> On 3 Nov 2007, at 20:27, Aryk Grosz wrote: >> which returns a Sql String. How the heck does it instantiate an array? >> And then how does that array have all the active record methods on it, >> like being able to do book.pages.find(:first). After all, the return >> object is of type Array, not some class that extends Array and >> includes >> those methods. >> > > say you have User, User has_many :addresses. > User.addresses is not an array. It looks like an array, it quacks like > an array but it''s actually an association proxy pretending to be an > array. It manages an actual array with the elements of the collection > and (via method_missing) lets that array handle most calls. > > FredSo why is it that when I do, User.addresses.class, I dont get HasManyAssociation, and Array instead? Where in AR does it actually make it so that calling .class will yield Array instead of the proxy class that it actually is. The HasManyAssociation class, for example, is not even superclassed by an array. -- Posted via http://www.ruby-forum.com/. --~--~---------~--~----~------------~-------~--~----~ 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 -~----------~----~----~----~------~----~------~--~---
On 3 Nov 2007, at 21:25, Aryk Grosz wrote:>> >> say you have User, User has_many :addresses. >> User.addresses is not an array. It looks like an array, it quacks >> like >> an array but it''s actually an association proxy pretending to be an >> array. It manages an actual array with the elements of the collection >> and (via method_missing) lets that array handle most calls. >> >> Fred > So why is it that when I do, User.addresses.class, I dont get > HasManyAssociation, and Array instead? Where in AR does it actually > make > it so that calling .class will yield Array instead of the proxy class > that it actually is. The HasManyAssociation class, for example, is not > even superclassed by an array.because the class method is also proxyed through to the target array, which returns Array because it is one. Fred --~--~---------~--~----~------------~-------~--~----~ 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 -~----------~----~----~----~------~----~------~--~---
when you say the class method, you mean like has_many, belongs_to, etc? Can you point to me in the code where this is done. Where lines of code are responsible for the "proxy through to the target array" part. Thanks for the help, Aryk Frederick Cheung wrote:> On 3 Nov 2007, at 21:25, Aryk Grosz wrote: >> HasManyAssociation, and Array instead? Where in AR does it actually >> make >> it so that calling .class will yield Array instead of the proxy class >> that it actually is. The HasManyAssociation class, for example, is not >> even superclassed by an array. > > because the class method is also proxyed through to the target array, > which returns Array because it is one. > > > Fred-- Posted via http://www.ruby-forum.com/. --~--~---------~--~----~------------~-------~--~----~ 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 -~----------~----~----~----~------~----~------~--~---
On 4 Nov 2007, at 02:02, Aryk Grosz wrote:> > when you say the class method, you mean like has_many, belongs_to, > etc? > Can you point to me in the code where this is done. Where lines of > code > are responsible for the "proxy through to the target array" part. >No I mean the method "class", which you call to get the class of an object. The code you are interested in is in association_proxy.rb> Thanks for the help, > Aryk > > > Frederick Cheung wrote: >> On 3 Nov 2007, at 21:25, Aryk Grosz wrote: >>> HasManyAssociation, and Array instead? Where in AR does it actually >>> make >>> it so that calling .class will yield Array instead of the proxy >>> class >>> that it actually is. The HasManyAssociation class, for example, is >>> not >>> even superclassed by an array. >> >> because the class method is also proxyed through to the target array, >> which returns Array because it is one. >> >> >> Fred > > -- > Posted via http://www.ruby-forum.com/. > > >--~--~---------~--~----~------------~-------~--~----~ 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 -~----------~----~----~----~------~----~------~--~---
Ok, Im looking in association_proxy.rb and I can''t find where they overwrite the "class" method to return Array. Should I be looking in a different file? Aryk Frederick Cheung wrote:> On 4 Nov 2007, at 02:02, Aryk Grosz wrote: > >> >> when you say the class method, you mean like has_many, belongs_to, >> etc? >> Can you point to me in the code where this is done. Where lines of >> code >> are responsible for the "proxy through to the target array" part. >> > No I mean the method "class", which you call to get the class of an > object. The code you are interested in is in association_proxy.rb-- Posted via http://www.ruby-forum.com/. --~--~---------~--~----~------------~-------~--~----~ 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 -~----------~----~----~----~------~----~------~--~---
On 5 Nov 2007, at 16:45, Aryk Grosz wrote:> > Ok, Im looking in association_proxy.rb and I can''t find where they > overwrite the "class" method to return Array. > > Should I be looking in a different file? >Nope. The point is that it''s not overwriting anything: it''s (at the top) undefining just about every method (including class) and then, in method_missing it forwards on the method to the target Fred> Aryk > > Frederick Cheung wrote: >> On 4 Nov 2007, at 02:02, Aryk Grosz wrote: >> >>> >>> when you say the class method, you mean like has_many, belongs_to, >>> etc? >>> Can you point to me in the code where this is done. Where lines of >>> code >>> are responsible for the "proxy through to the target array" part. >>> >> No I mean the method "class", which you call to get the class of an >> object. The code you are interested in is in association_proxy.rb > > -- > Posted via http://www.ruby-forum.com/. > > >--~--~---------~--~----~------------~-------~--~----~ 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 -~----------~----~----~----~------~----~------~--~---
Frederick Cheung wrote:> On 5 Nov 2007, at 16:45, Aryk Grosz wrote: > >> >> Ok, Im looking in association_proxy.rb and I can''t find where they >> overwrite the "class" method to return Array. >> >> Should I be looking in a different file? >> > Nope. The point is that it''s not overwriting anything: it''s (at the > top) undefining just about every method (including class) and then, in > method_missing it forwards on the method to the target > > Fredyup, now i got it! Thanks for the help, this has been bugging me for quite a while. Although, this seems very hacky to me, whats your take? -- Posted via http://www.ruby-forum.com/. --~--~---------~--~----~------------~-------~--~----~ 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 -~----------~----~----~----~------~----~------~--~---