Paperclip polymorphic styles

rubyonrails-talk
1

Hi, I have a polymorphic Image model that I am using on 2 very different models. I would like to have different image styles depending on the model.

I have been searching everwhere for an answer but I haven't be able to find something.

Does someone knows has to do that? GReg

2

Greg Ma wrote in post #970946:

Hi, I have a polymorphic Image model that I am using on 2 very different models. I would like to have different image styles depending on the model.

I have been searching everywhere for an answer but I haven't be able to find something.

I assume you would need to know, for a certain "image", for which of your 2 models this is used.

I am not familiar with Paperclip, but in general, if you use a polymorphic asociation, it is easy to find out to which model this "Image" object is linked to with self.association.class .

I made a little mock-up where an Image class has a polymorphic belongs_to association to classes "Person" and "User". What you could do is decide based on the class of the result of the association what you are looking at:

class Image < ActiveRecord::Base

  belongs_to :someone, :polymorphic => true

end

rails c Loading development environment (Rails 3.0.3) 001:0> image_1 = Image.new(:url => "http://flickr…") => #<Image id: nil, url: "http://flickr…", someone_type: nil, someone_id: nil, created_at: nil, updated_at: nil> 002:0> image_1.someone = User.first => #<User id: 1, first_name: "Jon", last_name: nil, user_name: nil, testing: nil, created_at: "2010-12-23 21:57:01", updated_at: "2010-12-23 21:57:01"> 003:0> image_1.save! => true 004:0> image_2 = Image.new(:url => "http://picassa…", :someone => Person.first) => #<Image id: nil, url: "http://picassa…", someone_type: "Person", someone_id: 1, created_at: nil, updated_at: nil> 005:0> image_2.save! => true 006:0> Image.all => [#<Image id: 3, url: "http://flickr…", someone_type: "User", someone_id: 1, created_at: "2010-12-27 20:45:01", updated_at: "2010-12-27 20:45:01">, #<Image id: 4, url: "http://picassa…", someone_type: "Person", someone_id: 1, created_at: "2010-12-27 20:45:36", updated_at: "2010-12-27 20:45:36">] 007:0> image_1.someone.class => User(id: integer, first_name: string, last_name: string, user_name: string, testing: string, created_at: datetime, updated_at: datetime) 008:0> image_2.someone.class => Person(id: integer, first_name: text, last_name: text, birth_date: date, gsm_number: text, comment: string, created_at: datetime, updated_at: datetime) 009:0> image_1.someone.class == User => true 010:0> image_1.someone.class == Person => false

The 'image.someone.class' will tell you if this image is used for a Person or for a User.

At a deeper level, one could also inspect the content of image.someone_type, but I feel that is not as clean, since this relies on the internals of a particular implementation of the polymorphic assocation.

011:0> image_1.someone_type => "User" 012:0> image_2.someone_type => "Person"

HTH,

Peter