Has_many 'Paperclip' output?

Rails
#1

#gem ‘rails’, ‘3.0.9’
#gem “paperclip”, “~> 2.0”

rails console

contract = Contract.first
=> #<Contract id: 1, . . .
files = contract.contract_files
=> [#<ContractFile id: 1, contract_id: 1, . . .
files.first.data.url
=> “/system/data/1/original/logo.png?1325513082”
files.map(&:data_file_name).each do |key| key end
=> [“logo.png”, “newyearseve-2011-res.jpg”, nil]
#IT WORKS FINE!

files.map(&:data.url).each do |key| key end
=> NoMethodError: undefined method `url’ for :data:Symbol
#IT DOESN’T WORK

Can you explain how to get access to “data.url” in has_many model?

#2

On Mon, Jan 2, 2012 at 10:02 PM, Nikolay [email protected] wrote:

files.map(&:data_file_name).each do |key| key end
=> [“logo.png”, “newyearseve-2011-res.jpg”, nil]
#IT WORKS FINE!

files.map(&:data.url).each do |key| key end
=> NoMethodError: undefined method `url’ for :data:Symbol
#IT DOESN’T WORK

Can you explain how to get access to “data.url” in has_many model?

Hmm… to my knowledge, & (unary operator) is converting to_proc on an
object.

so file.map(&:data_file_name) is equal to:
file.map {|i| i.data_file_name)

but on your second example

files.map(&:data.url) , ruby interpret it as call ‘url’ method on symbol
:data and call to_proc

hmm. I dont know the solution, but you might try

files.map do |file|
file.data.url
end

#3

Thank you, Ahmy!
Simple solutions always work fine.
That’s all we need.

#4

Well, you can’t because you’re not calling an instance method on every
element of your array. data_file_name works because each ContractFile
object has an attribute called data_file_name. So, you can call map() on
files and collect every filename by specifying data_file_name. In
contrast,
url is an instance method you have to call on every PaperClip attachment
and you can’t give it as a symbol. You have to specify it this way:

files.collect { |f| f.data.url }

2012/1/2 Nikolay [email protected]