Question

@models.map(&:attributes)) returns a list of hashes from each column to its value in the db

How do I limit it so that only specific columns are returns (e.g. just name and id?).

Also, how do I combine multiple columns to a new key => value pair? For example, if a user has first_name and last_name, the above would return

[{"first_name" => "foo", "last_name" => "bar"}] but I want it to be [{"name" => "foo bar"}]

How do I achieve this transformation? Thanks!

Answer 1

For the first part (limiting the attributes in the hash):

@models.map {|model| model.attributes.slice(:id, :name)}

For combining multiple attribute into a new attribute, the cleanest way is usually an accessor method:

class User < ActiveRecord::Base
  def name
    "#{first_name} #{last_name}"
  end
end

Then build your hash manually during iteration:

@models.map {|model| {:id => model.id, :name => model.name}}

If you’re using more than one attribute from the attributes hash, you can use merge:

@models.map do |model|
  model.attributes.slice(:id, :first_name, :last_name).merge(:name => model.name)
end