Question

Say that I have two resources, Project and Task. A Project can have many Tasks; A Task belongs to one Project. Also say that I have Task nested under Project in routes.rb:

map.resources :projects do |project|   project.resources :tasks end 

Can one programmatically discover this relationship? Basically, I need to dynamically load an arbitrary object, then figure out if it has a ‘parent’, and then load that parent.

Any ideas?

Answer 1

Routing will not help you as this is only meant to be used the other way around. What you can do is aliasing the relationship with :parent:

 class Task   belongs_to :project   alias :project :parent end 

And then use this relationship to detect if a parent object is available:

 if object.respond_to?(:parent)   # do something end 

Moreover, you can use polymorphic routes if the routes are set up correctly:

 polymorphic_url([object.parent, object])