In modern Rails versions you can also use ActiveRecord's
pluck
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method.
User.active.pluck(:id)
=> [1, 5, 23, 42]
If you are plucking from the id column in particular you can also say:
User.active.ids
=> [1, 5, 23, 42]
For a DISTINCT selection, use distinct on your scope (not the resulting array).
Article.distinct.pluck(:state)
# SELECT DISTINCT state FROM articles
=> ['draft', 'published']
In Rails 3 and 4 you must use uniq instead of distinct:
Article.uniq.pluck(:state)
# SELECT DISTINCT state FROM articles
=> ['draft', 'published']
Plucking columns in legacy Rails versions
For older Rails versions you can use the collect_column method from
Edge Rider
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for the same purpose as pluck.
Posted by Arne Hartherz to makandra dev (2010-09-13 17:57)