How to get enum value from its index in ruby-on-rails?

Question

For example I have this enum in ruby-on-rails:

class Foo < ActiveRecord::Base enum color: [ :red, :green, :blue ] end

By default, the index should be :red -> 0, :green -> 1, and so on.

I want to get the enum value by index, let's say from index 1, so the result should be :green. Is it possible to do this ?

Update:

Pseudo-code example:

Foo.colors.find_by_index(1) # returns :green

What if you have two columns with enums? How do you expect rails to work in that case? — Lavika
– Lavika, Commented Jan 7, 2018 at 21:18
I also use the enum for Formtastic's select input (e.g. f.input :color, as: :select, collection: Foo.colors). The enum index would be the option value, and the enum value itself as the display text/label. Array doesn't fit for this case I think. Another way is using Hash, but here I would like to know if it's possible to get enum value by index. — null
– null, Commented Jan 7, 2018 at 21:41
Okay well you could do as Foo.colors.keys(1) #=> "green" becuase colors is simply a HashWithIndifferentAccess so it acts very similar to a Hash but all the Symbol keys are going to be Strings. — engineersmnky
– engineersmnky, Commented Jan 8, 2018 at 19:10

mgidea · Accepted Answer · 2018-01-08 00:09:47Z

2

Foo.colors returns a hash:

{:red => 0, :green => 1, :blue => 2}

You can invert the hash to get the indexed value

Foo.colors.invert
# {0 => :red, 1 => :green, 2 => :blue}

answered Jan 8, 2018 at 0:09

mgidea

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1 Comment

William Romero Over a year ago

Great way to use enums when the value of the is a number. I used it like that: Products.categories.invert[@product.categories] and i got the name of the value and not the integer.

lg86 · Accepted Answer · 2018-01-08 04:11:04Z

0

You can try these

class Fooo < ActiveRecord::Base
  enum colo: {red: 0, green: 1, blue: 2}
end

answered Jan 8, 2018 at 4:11

lg86

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