On Feb 11, 9:25 am, Kendall Gifford <[email protected]> wrote:
> Hi list, how are ya?
>
> So, my current project is just begging for the ability to have
> parameterized associations in my ActiveRecord classes. Basically I
> need something that is a cross between named scopes and standard
> associations (has_many specifically).
>
> I'm wondering if such a thing exists or, if not, if anyone else has an
> elegant, equivalent solution?
>
> Example:
>
> class Sprocket < ActiveRecord::Base
> belongs_to :widget
> belongs_to :version
> end
>
> class Widget < ActiveRecord::Base
> has_many :sprockets
> has_many :versioned_sprockets, lambda do |v|
> :conditions => { :version => v }
> end
> end
>
> The idea behind the example is so I can do stuff like:
>
> def get_just_the_sprockets_i_need(callers_conditions)
> version = Version.find(magic_method_returning_just_the_right_id)
> widget = some_other_magic_method_returning_a_widget_instance
> widget.versioned_sprockets(version).all(:conditions =>
> callers_conditions)
> end
>
> I first considered just putting a named scope directly in the Sprocket
> class, giving me parameterized scoping. However, I specifically want
> to access my sprockets through a Widget, getting the implicit
> widget_id scoping that comes with the association. If worse comes to
> worse, I'll have an uglier named scope taking two parameters (does
> this work) instead of one:
>
> class Sprocket ...
> named_scope :versioned, lambda do |widget, version|
> :conditions => { :widget => widget, :version => version }
> end
> ...
> end
>
> Any ideas?
>
> Thanks.
Named scopes are already sufficient for what you're trying to achieve:
class Sprocket
named_scope :versioned, lambda { |version| {:conditions => {:version
=> version}} }
end
widget.sprockets.version(version).all(:conditions =>
callers_conditions)
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