Adding an array to a Class (rails)

Question

I'd like to make one of the attributes of my class an array. The class is "Course" and the attribute is Course.evals.

I tried using "serialize," ala http://duanesbrain.blogspot.com/2007/04/ruby-on-rails-persist-array-to-database.html, but for some reason it's not working. Here's my relevant code:

class Course < ActiveRecord::Base
  serialize :evals
end

But then when I go into the console, this happens:

ruby-1.9.2-p290 :043 > blah = Course.find(3)
 => #<Course id: 3, evals: nil> 
ruby-1.9.2-p290 :045 > blah.update_attribute :evals, "thing"
 => true 
ruby-1.9.2-p290 :047 > blah.evals << "thing2"
 => "thingthing2" 
ruby-1.9.2-p290 :048 > blah.save
 => true 
ruby-1.9.2-p290 :050 > blah.evals
 => "thingthing2"

So blah.evals << "thing2" simply adds "thing2" to the existing "thing" string. It doesn't create a new entry in any array. Does this mean that my program isn't picking up my "serialize" command within the Model? If so, how can I fix it?

roboles · Accepted Answer · 2011-09-30 18:42:36Z

1

I believe the problem is that when you initially assign a value to the attribute, its assigned as a string. If you want to store it as an array you need to initialise the variable as an array...

> blah = Course.find(3)
> blah.update_attribute :evals, ["thing"]

As a side note, you can add an optional param to the serialize method to determine which class the attribute should have when deserializing...

class Course < ActiveRecord::Base
  serialize :evals, Array
end

answered Sep 30, 2011 at 18:42

roboles

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