Polymorphic Associations

Rails
1

I have Titles and People, and I want a single Image class that can
apply to either. I’m reading the Rails API on Polymorphic
Associations, and I’m getting confused by the example. Can anyone
explain how to do this:

Title
has_many :images

Person
has_many :images

Image
belongs_to [either :image or :title]

Thanks very much in advance,

Walter

2

Image class belongs_to :image_interface, polymorphic => true

Other classes has_many :images, :as => :image_interface

Blog: http://random8.zenunit.com/
Twitter: http://twitter.com/random8r
Learn: http://sensei.zenunit.com/
New video up now at http://sensei.zenunit.com/
real fastcgi rails deploy process! Check it out now!

3

In my opinion, this API is borked. See my other message for usage but I
reckon the :as should be replaced with :using or something else

Blog: http://random8.zenunit.com/
Twitter: http://twitter.com/random8r
Learn: http://sensei.zenunit.com/
New video up now at http://sensei.zenunit.com/
real fastcgi rails deploy process! Check it out now!

4

Thanks very much. Good point, too.

Walter

5

Quite often you’ll see examples trying to bake the nature of “interface”
into the interface name. Things such as “attachable” or “imageable” and
the like, but what this is really trying to do is say “this model can
adhere to the interface named attachable”. Naming the interface
something strangely related to the model that provides the interface
such as “attachable” is IMHO trying to “name around” a problem which
needs to be more clearly labelled or re-engineered.

In my opinion the idea of interface needs to be built into ruby and
rails a bit better.

Blog: http://random8.zenunit.com/
Twitter: http://twitter.com/random8r
Learn: http://sensei.zenunit.com/
New video up now at http://sensei.zenunit.com/
real fastcgi rails deploy process! Check it out now!

6

Yeah because what you’re doing is programming / adhering to an
interface. This wording is the source of a huge amount of confusion for
many programmers.

Blog: http://random8.zenunit.com/
Twitter: http://twitter.com/random8r
Learn: http://sensei.zenunit.com/
New video up now at http://sensei.zenunit.com/
real fastcgi rails deploy process! Check it out now!