Accessing object attributes Rails 4

Question

I have an array arr = ["model", "engine", "year", ................] where each element is an attribute name of Car model.
I am trying to push these specific attribute values to another array

Car.all.each do |mycar|
  another_array << arr.map{ |attr| mycar.attr }
end

This of course gives the expected no method error .attr for <object>. What is the correct way to do this ?? EDIT I know about .send() method but I found that some fields encrypted using attr-encrypted gem are not decrypted properly when I use .send(). So I have to try something else like this

Ven · Accepted Answer · 2016-08-19 09:27:17Z

2

You needn't anything Rails/ActiveRecord specific.

If you're sure the attributes are "safe" (that is, the users couldn't have meddled with the list, or you validated the method names before), you can simply use ruby's send:

mycar.send(attr) # dangerous
mycar.public_send(attr) # a bit less dangerous. Keep reading for the correct solution..

ActiveRecord does provide a shortcut for this, however (that does checking for you):

mycar[attr]

edited Aug 19, 2016 at 9:27

answered Aug 19, 2016 at 8:58

Ven

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5 Comments

Tony Vincent Over a year ago

yes I know, I have been using .send method but since I use attr-encrypted gem I found some fields are not decrypted when using send method, rthats why I have to try somthing like this

Ven Over a year ago

you'll need to store your list with encrypted_ before

Tony Vincent Over a year ago

then I won't get decrypted value

Ven Over a year ago

a.b and a.send(:b) are literally the same. Use the correct method name as described in attr-encrypted.

Roman Kiselenko Over a year ago

public_send is safer here.

Deepak Mahakale · Accepted Answer · 2016-08-19 09:15:47Z

0

You can make use of attributes

Car.all.each do |mycar|
  another_array << mycar.attributes.slice("model", "engine", "year").values }
end

answered Aug 19, 2016 at 9:15

Deepak Mahakale

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1 Comment

Tony Vincent Over a year ago

Thanks for your help but I cant use .values because att-encrypted uses 'encrypted_' prefix before attributes.

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