CODEWITHSUNDEEP
ruby-on-railsrubyruby-on-rails-3activerecord
Adam
Adam

Reputation: 4074

Select objects by index of array in Rails 3

I'm trying to select a collection of objects using ActiveRecord by the index in the array.

I know I can select Item.first or Item.last or single or range. But I want to update an arbitrary group by the index of their position in the array.

collection = Item.all.to_a
collection[3,5,9,11]

Is this possible?

Thanks in advance...

-- edit --

Thanks to tokland's help, I was able to get it to work perfect.

In case anyone else wants to do something similar, here is what I did:

yesterday = Time.now - 1.day
i = Item.all
new_items = i.values_at(1,3,5,10,11,14,18)
new_items.each{ |e| e.update_attributes(:published_at => yesterday) }

Upvotes: 3

Views: 4488

Answers (2)

WarHog
WarHog

Reputation: 8710

If i properly understand, you need

Item.find([3,5,9,11])

This is how you can find a record given an id. But it method throws an exception if there would be some id that doesn't exist.

Item.find_all_by_id([3,5,9,11])

That will work even if some of the ids don't exist.

Upvotes: 1

tokland
tokland

Reputation: 67850

If you mean indexes in an array (not IDs):

collection.values_at(3, 5, 9, 11)

Upvotes: 8

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