On Thu, Dec 1, 2011 at 1:23 PM, Kioko -- <[email protected]> wrote:
> Hi there, > > I'd be happy if someone can help me with the following: > The application is for uploading all kinds of datafiles which should be > displayed accordingly to their mimetypes. > > This is the class/database hierarchy of what I want to archive: > > Class:Filegroup > has_many :binary > Attributes are e.g. groupname, timestamps of upload/update and so on > > Class:Binary > This is the generall description of the uploaded file > Attributes included are e.g. original_filename, mimetype and so on > > If someone is uploading a file with a known mimetype, a (sub-)class > should be created with specific details about the file e.g. > > Class:Image > Including width, height... > > Class:Text > Textstyle (php, xml)... > > > I'd like to access the list of *all* files through something like: > Filegroup.find(xxx).files iterates over it and render it automatically > as it is specified in each of those sub-classes (so images whould be a > thumbnail, text is shown fully and binary just a simple download link) > > I found the Polymorphic-attribute for the database associations but this > is the other way round, isn't it? > Also I took a look at > > http://archive.robwilkerson.org/2009/08/26/learning-ruby-on-rails-file-upload/index.html > but this isn't exactly what I need because the class which should be > used should be defined automatically. > (E.g. somewhere is specified which class should be used for which > mimetype) > I believe you need a mix of: * STI from Binary to Image, Text etc. * has_many relationships from Filegroup to these different classes. I set-up a project on https://github.com/petervandenabeele/files with as core files: class Binary < ActiveRecord::Base end class Filegroup < ActiveRecord::Base has_many :binaries has_many :images has_many :texts end class Image < Binary def show "this is an image of width #{width} and height #{height}" end end class Text < Binary def show "This is a text of size #{size}" end end and schema.rb : ActiveRecord::Schema.define(:version => 20111203233119) do create_table "binaries", :force => true do |t| t.string "filename" t.integer "filegroup_id" t.string "type" t.datetime "created_at" t.datetime "updated_at" t.integer "height" t.integer "width" t.integer "size" end create_table "filegroups", :force => true do |t| t.string "groupname" t.datetime "created_at" t.datetime "updated_at" end end And then I can call: fg.images.build fg.texts.build to _build_ instances of derived classes, but also fg.binaries to get back _all_ binaries (of different subclasses) where each binary (image, text) has it's own class specific implementation of a show method (different for an Image and for a Text). Is this what you where looking for ? Peter +++++++++++++++++++++++ peterv@ASUS:~/data/temp/files$ rails c Loading development environment (Rails 3.1.3) 001:0> fg = Filegroup.create(:groupname => "home") (0.1ms) SHOW search_path (0.1ms) BEGIN SQL (12.3ms) INSERT INTO "filegroups" ("created_at", "groupname", "updated_at") VALUES ($1, $2, $3) RETURNING "id" [["created_at", Sat, 03 Dec 2011 23:46:03 UTC +00:00], ["groupname", "home"], ["updated_at", Sat, 03 Dec 2011 23:46:03 UTC +00:00]] (0.6ms) COMMIT => #<Filegroup id: 1, groupname: "home", created_at: "2011-12-03 23:46:03", updated_at: "2011-12-03 23:46:03"> 002:0> fg.images.create(:width => "400", :height => "200") (0.2ms) BEGIN SQL (1.5ms) INSERT INTO "binaries" ("created_at", "filegroup_id", "filename", "height", "size", "type", "updated_at", "width") VALUES ($1, $2, $3, $4, $5, $6, $7, $8) RETURNING "id" [["created_at", Sat, 03 Dec 2011 23:46:34 UTC +00:00], ["filegroup_id", 1], ["filename", nil], ["height", 200], ["size", nil], ["type", "Image"], ["updated_at", Sat, 03 Dec 2011 23:46:34 UTC +00:00], ["width", 400]] (0.6ms) COMMIT => #<Image id: 1, filename: nil, filegroup_id: 1, type: "Image", created_at: "2011-12-03 23:46:34", updated_at: "2011-12-03 23:46:34", height: 200, width: 400, size: nil> 003:0> fg.texts.create(:size => 4000) (0.2ms) BEGIN SQL (0.8ms) INSERT INTO "binaries" ("created_at", "filegroup_id", "filename", "height", "size", "type", "updated_at", "width") VALUES ($1, $2, $3, $4, $5, $6, $7, $8) RETURNING "id" [["created_at", Sat, 03 Dec 2011 23:47:02 UTC +00:00], ["filegroup_id", 1], ["filename", nil], ["height", nil], ["size", 4000], ["type", "Text"], ["updated_at", Sat, 03 Dec 2011 23:47:02 UTC +00:00], ["width", nil]] (0.7ms) COMMIT => #<Text id: 2, filename: nil, filegroup_id: 1, type: "Text", created_at: "2011-12-03 23:47:02", updated_at: "2011-12-03 23:47:02", height: nil, width: nil, size: 4000> 004:0> fg.binaries Binary Load (0.9ms) SELECT "binaries".* FROM "binaries" WHERE "binaries"."filegroup_id" = 1 => [#<Image id: 1, filename: nil, filegroup_id: 1, type: "Image", created_at: "2011-12-03 23:46:34", updated_at: "2011-12-03 23:46:34", height: 200, width: 400, size: nil>, #<Text id: 2, filename: nil, filegroup_id: 1, type: "Text", created_at: "2011-12-03 23:47:02", updated_at: "2011-12-03 23:47:02", height: nil, width: nil, size: 4000>] # Note that the 2 objects are of class Image and class Text (not of class Binary) ! 005:0> fg.binaries.each{|b| puts b.show} this is an image of width 400 and height 200 This is a text of size 4000 ... -- You received this message because you are subscribed to the Google Groups "Ruby on Rails: Talk" group. To post to this group, send email to [email protected]. To unsubscribe from this group, send email to [email protected]. For more options, visit this group at http://groups.google.com/group/rubyonrails-talk?hl=en.
