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delete

delete(*records)
Instance Public methods

Deletes the records supplied and removes them from the collection. For has_many associations, the deletion is done according to the strategy specified by the :dependent option. Returns an array with the deleted records.

If no :dependent option is given, then it will follow the default strategy. The default strategy is :nullify. This sets the foreign keys to NULL. For, has_many :through, the default strategy is delete_all.

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class Person < ActiveRecord::Base
  has_many :pets # dependent: :nullify option by default
end
 
person.pets.size # => 3
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.delete(Pet.find(1))
# => [#<Pet id: 1, name: "Fancy-Fancy", person_id: 1>]
 
person.pets.size # => 2
person.pets
# => [
#       #<Pet id: 2, name: "Spook", person_id: 1>,
#       #<Pet id: 3, name: "Choo-Choo", person_id: 1>
#    ]
 
Pet.find(1)
# => #<Pet id: 1, name: "Fancy-Fancy", person_id: nil>

If it is set to :destroy all the records are removed by calling their destroy method. See destroy for more information.

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class Person < ActiveRecord::Base
  has_many :pets, dependent: :destroy
end
 
person.pets.size # => 3
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.delete(Pet.find(1), Pet.find(3))
# => [
#       #<Pet id: 1, name: "Fancy-Fancy", person_id: 1>,
#       #<Pet id: 3, name: "Choo-Choo", person_id: 1>
#    ]
 
person.pets.size # => 1
person.pets
# => [#<Pet id: 2, name: "Spook", person_id: 1>]
 
Pet.find(1, 3)
# => ActiveRecord::RecordNotFound: Couldn't find all Pets with IDs (1, 3)

If it is set to :delete_all, all the records are deleted without calling their destroy method.

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class Person < ActiveRecord::Base
  has_many :pets, dependent: :delete_all
end
 
person.pets.size # => 3
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.delete(Pet.find(1))
# => [#<Pet id: 1, name: "Fancy-Fancy", person_id: 1>]
 
person.pets.size # => 2
person.pets
# => [
#       #<Pet id: 2, name: "Spook", person_id: 1>,
#       #<Pet id: 3, name: "Choo-Choo", person_id: 1>
#    ]
 
Pet.find(1)
# => ActiveRecord::RecordNotFound: Couldn't find Pet with id=1

You can pass Fixnum or String values, it finds the records responding to the id and executes delete on them.

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class Person < ActiveRecord::Base
  has_many :pets
end
 
person.pets.size # => 3
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.delete("1")
# => [#<Pet id: 1, name: "Fancy-Fancy", person_id: 1>]
 
person.pets.delete(2, 3)
# => [
#       #<Pet id: 2, name: "Spook", person_id: 1>,
#       #<Pet id: 3, name: "Choo-Choo", person_id: 1>
#    ]
doc_ruby_on_rails
doc_ruby_on_rails
2025-01-10 15:47:30
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