pluck(*column_names) public

Use #pluck as a shortcut to select one or more attributes without loading a bunch of records just to grab the attributes you want.

Person.pluck(:name)

instead of

Person.all.map(&:name)

Pluck returns an Array of attribute values type-casted to match the plucked column names, if they can be deduced. Plucking an SQL fragment returns String values by default.

Person.pluck(:name)
# SELECT people.name FROM people
# => ['David', 'Jeremy', 'Jose']

Person.pluck(:id, :name)
# SELECT people.id, people.name FROM people
# => [[1, 'David'], [2, 'Jeremy'], [3, 'Jose']]

Person.distinct.pluck(:role)
# SELECT DISTINCT role FROM people
# => ['admin', 'member', 'guest']

Person.where(age: 21).limit(5).pluck(:id)
# SELECT people.id FROM people WHERE people.age = 21 LIMIT 5
# => [2, 3]

Person.pluck(Arel.sql('DATEDIFF(updated_at, created_at)'))
# SELECT DATEDIFF(updated_at, created_at) FROM people
# => ['0', '27761', '173']

See also #ids.

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January 8, 2015 - (v4.1.8)
3 thanks

Text improvement

Where it says: without loading a bunch of records should say: without loading a bunch of columns/attributes Considering that record usually is a row.

March 10, 2021
0 thanks

Text improvement

The statement about not loading a bunch of records is correct because pluck returns an Array of values, not a ActiveRecord::Relation or an Array of Records.

The exact wording though may be:

“…without retrieving from the database unused columns or loading a bunch of records just to grab the attributes you want”