How do I convert an ActiveRecord result array to a normal array?

Question

How do I convert the resultset of @recipe.components.find ( [# <Component ingredient_id: 1>, # <Component> ingredient_id: 2>] ) to an array such as [1,2]

<% @ingredients.each do |ingredient| %>
  <div class="field">
  <%= check_box_tag 'ingredients[]', ingredient.id, @recipe.components.find(:all, :select => "ingredient_id").include?(ingredient.id) %><%= ingredient.name %>
  </div>
<% end %>

Thanks!

nonopolarity · Accepted Answer · 2010-11-22 00:13:59Z

34

you can use

@result.map {|i| i.ingredient_id }

answered Nov 22, 2010 at 0:13

nonopolarity

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2 Comments

Spechal Over a year ago

Thanks! I needed @result.map! { |i| i.ingredient_id }

the Tin Man Over a year ago

map is your friend. Also get to know the "ect" triplets: select, reject and inject.

vvohra87 · Accepted Answer · 2011-11-18 13:23:20Z

25

If you are using a recent version of ruby, there is new way to do this:

@result.map(&:ingredient_id)

Time saver, clean and easy to interpret.

answered Nov 18, 2011 at 13:23

vvohra87

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3 Comments

Spechal Over a year ago

Looks like Ruby is gaining even more ability to be cryptic then.

vvohra87 Over a year ago

@Spechal it's not to be cryptic! Simply put, the map method exposes the underlying enumeration interface for any array, hash, etc. The "&" is just short notation when you wish to send / trigger a single method on each object in the array. And in this case the :ingredient_id is the symbol representation of the method.

vvohra87 Over a year ago

@Spechal Oh and I forgot to mention, if you are using Rails 3.2.x there is a simpler method! Just call MyModel.find(conditions).pluck(&:ingredient_id)... this is much faster since the pluck method is basically a single column select so you wont waste time in fetching all the data, presuming of course that you only want the values in a single column!

Lucas Wiman · Accepted Answer · 2011-03-23 00:28:07Z

6

Or more succinctly @result.map! &:ingredient_id

answered Mar 23, 2011 at 0:28

Lucas Wiman

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Comments

hongxingshi · Accepted Answer · 2014-03-03 07:11:05Z

6

You could also use:

@result.pluck(:ingredient_id)

answered Mar 3, 2014 at 7:11

hongxingshi

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