Ruby on Rails - Get array of values from array of hash with particular order of existing keys

Question

The original array likes this:

[{:age=>28, :name=>"John", :id=>1}, {:name=>"David", :age=>20, :id=>2, :sex=>"male"}]

Order of existing keys:

[:id, :name, :age] or ['id', 'name', 'age']

The result should be:

[[1, "John", 28], [2, "David", 20]]

Thank for teaching me.

P/s: I am using Ruby 1.8.7 and Rails 2.3.5

Thanks

Answer 1

Here is a nice way using #values_at :

records = [
  {:age=>28, :name=>"John", :id=>1},
  {:name=>"David", :age=>20, :id=>2, :sex=>"male"}
]

attributes = [:id, :name, :age]

records.collect { |h| h.values_at(*attributes) }
# => [[1, "John", 28], [2, "David", 20]]

Answer 2

Map all the records and then map the attributes in the order given to return the attributes' values in the specified order.

records = [
  {:age=>28, :name=>"John", :id=>1},
  {:name=>"David", :age=>20, :id=>2, :sex=>"male"}
]

attributes = [:id, :name, :age]
records.map do |record|
  attributes.map { |attr| record[attr] }
end