Question

I have a model that I’m trying to retrieve an array of data from, and I don’t need the data to be instantiated into Ruby objects. In fact, that just introduces an extra step into my code to step through the objects and generate a new array with just the data I need.

Example:

class Book
  #has attribute in database title
end

I would like to generate an array which contains all the titles of all the Books in the database. What’s the best way to do it?

Answer 1

ActiveRecord gives you a direct hook to the current environment database, allowing you execute SQL statements and returning the result in basic structures (arrays or hashes). See: http://ar.rubyonrails.org/classes/ActiveRecord/ConnectionAdapters/DatabaseStatements.html

For example:

ActiveRecord::Base.connection.select_values("SELECT title FROM books")

Will return an array of book titles (strings). This will not instantiate any ActiveRecord instances and will be more memory efficient for your application.