Rails%203%20In%20Action

9.1.3 Using Paperclip
Attaching a file
When you run bin/cucumber features/creating_tickets.feature again, you’re
told your model is missing one more thing:
When I press "Create Ticket"
Ticket model missing required attr_accessor
for 'asset_file_name' (Paperclip::PaperclipError)
attr_accessor references a Ruby method that defines a setter and a getter method
named after its arguments, such as in the following listing.
Listing 9.3 attr_accessor example
attr_accessor :foo
# is the same as...
def foo
@foo
end
def foo=(value)
@foo = value
end
These getter and setter methods are defined automatically by Active Model for the
fields in your database. Paperclip wants the asset_file_name method defined on
your Ticket instance’s method. asset_file_name is one of four methods used by
Paperclip to track details about the file. The other methods are asset_content_type,
asset_file_size, and asset_updated_at. To define the asset_file_name method
and its siblings, create a migration that adds them as attributes of the Ticket model by
running this command:
rails g paperclip ticket asset
This paperclip generator (provided by the Paperclip gem) adds the proper fields to
your tickets table. You tell it you want the attachment to be called asset.
By running this command, you get a new file in db/migrate that ends with
_add_attachment_asset_to_ticket.rb. If you open this file now, you should see a prefilled
migration, as shown in the following listing.
Listing 9.4 db/migrate/[time]_add_attachment_asset_to_ticket.rb
class AddAttachmentAssetToTicket < ActiveRecord::Migration
def self.up
add_column :tickets, :asset_file_name, :string
add_column :tickets, :asset_content_type, :string
add_column :tickets, :asset_file_size, :integer
add_column :tickets, :asset_updated_at, :datetime
end
def self.down
remove_column :tickets, :asset_file_name
remove_column :tickets, :asset_content_type
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