Method: ActiveRecord::Persistence::ClassMethods#query_constraints

Defined in:
activerecord/lib/active_record/persistence.rb

#query_constraints(*columns_list) ⇒ Object

Accepts a list of attribute names to be used in the WHERE clause of SELECT / UPDATE / DELETE queries and in the ORDER BY clause for #first and #last finder methods.

class Developer < ActiveRecord::Base
  query_constraints :company_id, :id
end

developer = Developer.first
# SELECT "developers".* FROM "developers" ORDER BY "developers"."company_id" ASC, "developers"."id" ASC LIMIT 1
developer.inspect # => #<Developer id: 1, company_id: 1, ...>

developer.update!(name: "Nikita")
# UPDATE "developers" SET "name" = 'Nikita' WHERE "developers"."company_id" = 1 AND "developers"."id" = 1

# It is possible to update an attribute used in the query_constraints clause:
developer.update!(company_id: 2)
# UPDATE "developers" SET "company_id" = 2 WHERE "developers"."company_id" = 1 AND "developers"."id" = 1

developer.name = "Bob"
developer.save!
# UPDATE "developers" SET "name" = 'Bob' WHERE "developers"."company_id" = 1 AND "developers"."id" = 1

developer.destroy!
# DELETE FROM "developers" WHERE "developers"."company_id" = 1 AND "developers"."id" = 1

developer.delete
# DELETE FROM "developers" WHERE "developers"."company_id" = 1 AND "developers"."id" = 1

developer.reload
# SELECT "developers".* FROM "developers" WHERE "developers"."company_id" = 1 AND "developers"."id" = 1 LIMIT 1

Raises:

  • (ArgumentError) 


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# File 'activerecord/lib/active_record/persistence.rb', line 212

def query_constraints(*columns_list)
  raise ArgumentError, "You must specify at least one column to be used in querying" if columns_list.empty?

  @query_constraints_list = columns_list.map(&:to_s)
  @has_query_constraints = @query_constraints_list
end