Comments on: Rails/ActiveRecord: belongs_to :polymorphic => true http://www.jtanium.com/2009/10/22/railsactiverecord-belongs_to-polymorphic-true/ I jot things down, in hopes of finding them later... Tue, 31 Jan 2012 15:07:04 +0000 hourly 1 http://wordpress.org/?v= By: Andy http://www.jtanium.com/2009/10/22/railsactiverecord-belongs_to-polymorphic-true/comment-page-1/#comment-4660 Andy Tue, 15 Nov 2011 14:47:59 +0000 http://www.jtanium.com/?p=161#comment-4660 Very good and useful. Thanks Very good and useful. Thanks

]]> By: jtanium http://www.jtanium.com/2009/10/22/railsactiverecord-belongs_to-polymorphic-true/comment-page-1/#comment-421 jtanium Mon, 07 Dec 2009 01:39:42 +0000 http://www.jtanium.com/?p=161#comment-421 Yes, in this respect has_one and has_many function similarly. I was just trying to come up with an example to demonstrate it's use. Now, as far as belongs_to :book, belongs_to :album, and belongs_to :movie, sure you could do that, but then when you try to use the item associated with the artwork you're going to have to do something ugly like: if artwork.book # do book stuff here elsif artwork.movie # do movie stuff here elsif artwork.album # do album stuff here else # uh oh! end This makes your code brittle, not to mention tedious. This polymorphic association provides you with a layer of indirection (a.k.a. abstraction) that would protect you from something such as adding another "belongs_to :" (e.g. :video_game). Yes, in this respect has_one and has_many function similarly. I was just trying to come up with an example to demonstrate it’s use.

Now, as far as belongs_to :book, belongs_to :album, and belongs_to :movie, sure you could do that, but then when you try to use the item associated with the artwork you’re going to have to do something ugly like:

if artwork.book
# do book stuff here
elsif artwork.movie
# do movie stuff here
elsif artwork.album
# do album stuff here
else
# uh oh!
end

This makes your code brittle, not to mention tedious. This polymorphic association provides you with a layer of indirection (a.k.a. abstraction) that would protect you from something such as adding another “belongs_to :” (e.g. :video_game).

]]> By: about2flip http://www.jtanium.com/2009/10/22/railsactiverecord-belongs_to-polymorphic-true/comment-page-1/#comment-420 about2flip Sun, 06 Dec 2009 18:14:37 +0000 http://www.jtanium.com/?p=161#comment-420 Couldn't book, album and movie has_many instead of has_one? Also, why couldn't Artwork model belongs_to :book, belongs_to :album, belongs_to :movie Thanks Couldn’t book, album and movie has_many instead of has_one?
Also, why couldn’t Artwork model belongs_to :book, belongs_to :album, belongs_to :movie

Thanks

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