method
select
v7.1.3.4 -
Show latest stable
-
0 notes -
Class: CollectionProxy
- 1.0.0
- 1.1.6
- 1.2.6
- 2.0.3
- 2.1.0
- 2.2.1
- 2.3.8
- 3.0.0
- 3.0.9
- 3.1.0
- 3.2.1
- 3.2.8
- 3.2.13
- 4.0.2 (0)
- 4.1.8 (3)
- 4.2.1 (0)
- 4.2.7 (0)
- 4.2.9 (0)
- 5.0.0.1 (0)
- 5.1.7 (-38)
- 5.2.3 (0)
- 6.0.0 (0)
- 6.1.3.1 (1)
- 6.1.7.7 (0)
- 7.0.0 (0)
- 7.1.3.2 (7)
- 7.1.3.4 (0)
- What's this?
select
public
Works in two ways.
First: Specify a subset of fields to be selected from the result set.
class Person < ActiveRecord::Base has_many :pets end person.pets # => [ # #<Pet id: 1, name: "Fancy-Fancy", person_id: 1>, # #<Pet id: 2, name: "Spook", person_id: 1>, # #<Pet id: 3, name: "Choo-Choo", person_id: 1> # ] person.pets.select(:name) # => [ # #<Pet id: nil, name: "Fancy-Fancy">, # #<Pet id: nil, name: "Spook">, # #<Pet id: nil, name: "Choo-Choo"> # ] person.pets.select(:id, :name) # => [ # #<Pet id: 1, name: "Fancy-Fancy">, # #<Pet id: 2, name: "Spook">, # #<Pet id: 3, name: "Choo-Choo"> # ]
Be careful because this also means you’re initializing a model object with only the fields that you’ve selected. If you attempt to access a field except id that is not in the initialized record you’ll receive:
person.pets.select(:name).first.person_id # => ActiveModel::MissingAttributeError: missing attribute 'person_id' for Pet
Second: You can pass a block so it can be used just like Array#select. This builds an array of objects from the database for the scope, converting them into an array and iterating through them using Array#select.
person.pets.select { |pet| /oo/.match?(pet.name) } # => [ # #<Pet id: 2, name: "Spook", person_id: 1>, # #<Pet id: 3, name: "Choo-Choo", person_id: 1> # ]