On Thu, Dec 1, 2011 at 1:23 PM, Kioko – [email protected] wrote:
Attributes are e.g. groupname, timestamps of upload/update and so on
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
…
