activerecord/lib/active_record/relation/finder_methods.rb
# frozen_string_literal: true
require "active_support/core_ext/string/filters"
module ActiveRecord
module FinderMethods
ONE_AS_ONE = "1 AS one"
# Find by id - This can either be a specific id (ID), a list of ids (ID, ID, ID), or an array of ids ([ID, ID, ID]).
# `ID` refers to an "identifier". For models with a single-column primary key, `ID` will be a single value,
# and for models with a composite primary key, it will be an array of values.
# If one or more records cannot be found for the requested ids, then ActiveRecord::RecordNotFound will be raised.
# If the primary key is an integer, find by id coerces its arguments by using +to_i+.
#
# Person.find(1) # returns the object for ID = 1
# Person.find("1") # returns the object for ID = 1
# Person.find("31-sarah") # returns the object for ID = 31
# Person.find(1, 2, 6) # returns an array for objects with IDs in (1, 2, 6)
# Person.find([7, 17]) # returns an array for objects with IDs in (7, 17), or with composite primary key [7, 17]
# Person.find([1]) # returns an array for the object with ID = 1
# Person.where("administrator = 1").order("created_on DESC").find(1)
#
# ==== Find a record for a composite primary key model
# TravelRoute.primary_key = [:origin, :destination]
#
# TravelRoute.find(["Ottawa", "London"])
# => #<TravelRoute origin: "Ottawa", destination: "London">
#
# TravelRoute.find([["Paris", "Montreal"]])
# => [#<TravelRoute origin: "Paris", destination: "Montreal">]
#
# TravelRoute.find(["New York", "Las Vegas"], ["New York", "Portland"])
# => [
# #<TravelRoute origin: "New York", destination: "Las Vegas">,
# #<TravelRoute origin: "New York", destination: "Portland">
# ]
#
# TravelRoute.find([["Berlin", "London"], ["Barcelona", "Lisbon"]])
# => [
# #<TravelRoute origin: "Berlin", destination: "London">,
# #<TravelRoute origin: "Barcelona", destination: "Lisbon">
# ]
#
# NOTE: The returned records are in the same order as the ids you provide.
# If you want the results to be sorted by database, you can use ActiveRecord::QueryMethods#where
# method and provide an explicit ActiveRecord::QueryMethods#order option.
# But ActiveRecord::QueryMethods#where method doesn't raise ActiveRecord::RecordNotFound.
#
# ==== Find with lock
#
# Example for find with a lock: Imagine two concurrent transactions:
# each will read <tt>person.visits == 2</tt>, add 1 to it, and save, resulting
# in two saves of <tt>person.visits = 3</tt>. By locking the row, the second
# transaction has to wait until the first is finished; we get the
# expected <tt>person.visits == 4</tt>.
#
# Person.transaction do
# person = Person.lock(true).find(1)
# person.visits += 1
# person.save!
# end
#
# ==== Variations of #find
#
# Person.where(name: 'Spartacus', rating: 4)
# # returns a chainable list (which can be empty).
#
# Person.find_by(name: 'Spartacus', rating: 4)
# # returns the first item or nil.
#
# Person.find_or_initialize_by(name: 'Spartacus', rating: 4)
# # returns the first item or returns a new instance (requires you call .save to persist against the database).
#
# Person.find_or_create_by(name: 'Spartacus', rating: 4)
# # returns the first item or creates it and returns it.
#
# ==== Alternatives for #find
#
# Person.where(name: 'Spartacus', rating: 4).exists?(conditions = :none)
# # returns a boolean indicating if any record with the given conditions exist.
#
# Person.where(name: 'Spartacus', rating: 4).select("field1, field2, field3")
# # returns a chainable list of instances with only the mentioned fields.
#
# Person.where(name: 'Spartacus', rating: 4).ids
# # returns an Array of ids.
#
# Person.where(name: 'Spartacus', rating: 4).pluck(:field1, :field2)
# # returns an Array of the required fields.
#
# ==== Edge Cases
#
# Person.find(37) # raises ActiveRecord::RecordNotFound exception if the record with the given ID does not exist.
# Person.find([37]) # raises ActiveRecord::RecordNotFound exception if the record with the given ID in the input array does not exist.
# Person.find(nil) # raises ActiveRecord::RecordNotFound exception if the argument is nil.
# Person.find([]) # returns an empty array if the argument is an empty array.
# Person.find # raises ActiveRecord::RecordNotFound exception if the argument is not provided.
def find(*args)
return super if block_given?
find_with_ids(*args)
end
# Finds the first record matching the specified conditions. There
# is no implied ordering so if order matters, you should specify it
# yourself.
#
# If no record is found, returns <tt>nil</tt>.
#
# Post.find_by name: 'Spartacus', rating: 4
# Post.find_by "published_at < ?", 2.weeks.ago
def find_by(arg, *args)
where(arg, *args).take
end
# Like #find_by, except that if no record is found, raises
# an ActiveRecord::RecordNotFound error.
def find_by!(arg, *args)
where(arg, *args).take!
end
# Gives a record (or N records if a parameter is supplied) without any implied
# order. The order will depend on the database implementation.
# If an order is supplied it will be respected.
#
# Person.take # returns an object fetched by SELECT * FROM people LIMIT 1
# Person.take(5) # returns 5 objects fetched by SELECT * FROM people LIMIT 5
# Person.where(["name LIKE '%?'", name]).take
def take(limit = nil)
limit ? find_take_with_limit(limit) : find_take
end
# Same as #take but raises ActiveRecord::RecordNotFound if no record
# is found. Note that #take! accepts no arguments.
def take!
take || raise_record_not_found_exception!
end
# Finds the sole matching record. Raises ActiveRecord::RecordNotFound if no
# record is found. Raises ActiveRecord::SoleRecordExceeded if more than one
# record is found.
#
# Product.where(["price = %?", price]).sole
def sole
found, undesired = first(2)
if found.nil?
raise_record_not_found_exception!
elsif undesired.present?
raise ActiveRecord::SoleRecordExceeded.new(self)
else
found
end
end
# Finds the sole matching record. Raises ActiveRecord::RecordNotFound if no
# record is found. Raises ActiveRecord::SoleRecordExceeded if more than one
# record is found.
#
# Product.find_sole_by(["price = %?", price])
def find_sole_by(arg, *args)
where(arg, *args).sole
end
# Find the first record (or first N records if a parameter is supplied).
# If no order is defined it will order by primary key.
#
# Person.first # returns the first object fetched by SELECT * FROM people ORDER BY people.id LIMIT 1
# Person.where(["user_name = ?", user_name]).first
# Person.where(["user_name = :u", { u: user_name }]).first
# Person.order("created_on DESC").offset(5).first
# Person.first(3) # returns the first three objects fetched by SELECT * FROM people ORDER BY people.id LIMIT 3
#
def first(limit = nil)
if limit
find_nth_with_limit(0, limit)
else
find_nth 0
end
end
# Same as #first but raises ActiveRecord::RecordNotFound if no record
# is found. Note that #first! accepts no arguments.
def first!
first || raise_record_not_found_exception!
end
# Find the last record (or last N records if a parameter is supplied).
# If no order is defined it will order by primary key.
#
# Person.last # returns the last object fetched by SELECT * FROM people
# Person.where(["user_name = ?", user_name]).last
# Person.order("created_on DESC").offset(5).last
# Person.last(3) # returns the last three objects fetched by SELECT * FROM people.
#
# Take note that in that last case, the results are sorted in ascending order:
#
# [#<Person id:2>, #<Person id:3>, #<Person id:4>]
#
# and not:
#
# [#<Person id:4>, #<Person id:3>, #<Person id:2>]
def last(limit = nil)
return find_last(limit) if loaded? || has_limit_or_offset?
result = ordered_relation.limit(limit)
result = result.reverse_order!
limit ? result.reverse : result.first
end
# Same as #last but raises ActiveRecord::RecordNotFound if no record
# is found. Note that #last! accepts no arguments.
def last!
last || raise_record_not_found_exception!
end
# Find the second record.
# If no order is defined it will order by primary key.
#
# Person.second # returns the second object fetched by SELECT * FROM people
# Person.offset(3).second # returns the second object from OFFSET 3 (which is OFFSET 4)
# Person.where(["user_name = :u", { u: user_name }]).second
def second
find_nth 1
end
# Same as #second but raises ActiveRecord::RecordNotFound if no record
# is found.
def second!
second || raise_record_not_found_exception!
end
# Find the third record.
# If no order is defined it will order by primary key.
#
# Person.third # returns the third object fetched by SELECT * FROM people
# Person.offset(3).third # returns the third object from OFFSET 3 (which is OFFSET 5)
# Person.where(["user_name = :u", { u: user_name }]).third
def third
find_nth 2
end
# Same as #third but raises ActiveRecord::RecordNotFound if no record
# is found.
def third!
third || raise_record_not_found_exception!
end
# Find the fourth record.
# If no order is defined it will order by primary key.
#
# Person.fourth # returns the fourth object fetched by SELECT * FROM people
# Person.offset(3).fourth # returns the fourth object from OFFSET 3 (which is OFFSET 6)
# Person.where(["user_name = :u", { u: user_name }]).fourth
def fourth
find_nth 3
end
# Same as #fourth but raises ActiveRecord::RecordNotFound if no record
# is found.
def fourth!
fourth || raise_record_not_found_exception!
end
# Find the fifth record.
# If no order is defined it will order by primary key.
#
# Person.fifth # returns the fifth object fetched by SELECT * FROM people
# Person.offset(3).fifth # returns the fifth object from OFFSET 3 (which is OFFSET 7)
# Person.where(["user_name = :u", { u: user_name }]).fifth
def fifth
find_nth 4
end
# Same as #fifth but raises ActiveRecord::RecordNotFound if no record
# is found.
def fifth!
fifth || raise_record_not_found_exception!
end
# Find the forty-second record. Also known as accessing "the reddit".
# If no order is defined it will order by primary key.
#
# Person.forty_two # returns the forty-second object fetched by SELECT * FROM people
# Person.offset(3).forty_two # returns the forty-second object from OFFSET 3 (which is OFFSET 44)
# Person.where(["user_name = :u", { u: user_name }]).forty_two
def forty_two
find_nth 41
end
# Same as #forty_two but raises ActiveRecord::RecordNotFound if no record
# is found.
def forty_two!
forty_two || raise_record_not_found_exception!
end
# Find the third-to-last record.
# If no order is defined it will order by primary key.
#
# Person.third_to_last # returns the third-to-last object fetched by SELECT * FROM people
# Person.offset(3).third_to_last # returns the third-to-last object from OFFSET 3
# Person.where(["user_name = :u", { u: user_name }]).third_to_last
def third_to_last
find_nth_from_last 3
end
# Same as #third_to_last but raises ActiveRecord::RecordNotFound if no record
# is found.
def third_to_last!
third_to_last || raise_record_not_found_exception!
end
# Find the second-to-last record.
# If no order is defined it will order by primary key.
#
# Person.second_to_last # returns the second-to-last object fetched by SELECT * FROM people
# Person.offset(3).second_to_last # returns the second-to-last object from OFFSET 3
# Person.where(["user_name = :u", { u: user_name }]).second_to_last
def second_to_last
find_nth_from_last 2
end
# Same as #second_to_last but raises ActiveRecord::RecordNotFound if no record
# is found.
def second_to_last!
second_to_last || raise_record_not_found_exception!
end
# Returns true if a record exists in the table that matches the +id+ or
# conditions given, or false otherwise. The argument can take six forms:
#
# * Integer - Finds the record with this primary key.
# * String - Finds the record with a primary key corresponding to this
# string (such as <tt>'5'</tt>).
# * Array - Finds the record that matches these +where+-style conditions
# (such as <tt>['name LIKE ?', "%#{query}%"]</tt>).
# * Hash - Finds the record that matches these +where+-style conditions
# (such as <tt>{name: 'David'}</tt>).
# * +false+ - Returns always +false+.
# * No args - Returns +false+ if the relation is empty, +true+ otherwise.
#
# For more information about specifying conditions as a hash or array,
# see the Conditions section in the introduction to ActiveRecord::Base.
#
# Note: You can't pass in a condition as a string (like <tt>name =
# 'Jamie'</tt>), since it would be sanitized and then queried against
# the primary key column, like <tt>id = 'name = \'Jamie\''</tt>.
#
# Person.exists?(5)
# Person.exists?('5')
# Person.exists?(['name LIKE ?', "%#{query}%"])
# Person.exists?(id: [1, 4, 8])
# Person.exists?(name: 'David')
# Person.exists?(false)
# Person.exists?
# Person.where(name: 'Spartacus', rating: 4).exists?
def exists?(conditions = :none)
return false if @none
if Base === conditions
raise ArgumentError, <<-MSG.squish
You are passing an instance of ActiveRecord::Base to `exists?`.
Please pass the id of the object by calling `.id`.
MSG
end
return false if !conditions || limit_value == 0
if eager_loading?
relation = apply_join_dependency(eager_loading: false)
return relation.exists?(conditions)
end
relation = construct_relation_for_exists(conditions)
return false if relation.where_clause.contradiction?
skip_query_cache_if_necessary do
with_connection do |c|
c.select_rows(relation.arel, "#{name} Exists?").size == 1
end
end
end
# Returns true if the relation contains the given record or false otherwise.
#
# No query is performed if the relation is loaded; the given record is
# compared to the records in memory. If the relation is unloaded, an
# efficient existence query is performed, as in #exists?.
def include?(record)
# The existing implementation relies on receiving an Active Record instance as the input parameter named record.
# Any non-Active Record object passed to this implementation is guaranteed to return `false`.
return false unless record.is_a?(klass)
if loaded? || offset_value || limit_value || having_clause.any?
records.include?(record)
else
id = if record.class.composite_primary_key?
record.class.primary_key.zip(record.id).to_h
else
record.id
end
exists?(id)
end
end
alias :member? :include?
# This method is called whenever no records are found with either a single
# id or multiple ids and raises an ActiveRecord::RecordNotFound exception.
#
# The error message is different depending on whether a single id or
# multiple ids are provided. If multiple ids are provided, then the number
# of results obtained should be provided in the +result_size+ argument and
# the expected number of results should be provided in the +expected_size+
# argument.
def raise_record_not_found_exception!(ids = nil, result_size = nil, expected_size = nil, key = primary_key, not_found_ids = nil) # :nodoc:
conditions = " [#{arel.where_sql(klass)}]" unless where_clause.empty?
name = @klass.name
if ids.nil?
error = +"Couldn't find #{name}"
error << " with#{conditions}" if conditions
raise RecordNotFound.new(error, name, key)
elsif Array.wrap(ids).size == 1
error = "Couldn't find #{name} with '#{key}'=#{ids}#{conditions}"
raise RecordNotFound.new(error, name, key, ids)
else
error = +"Couldn't find all #{name.pluralize} with '#{key}': "
error << "(#{ids.join(", ")})#{conditions} (found #{result_size} results, but was looking for #{expected_size})."
error << " Couldn't find #{name.pluralize(not_found_ids.size)} with #{key.to_s.pluralize(not_found_ids.size)} #{not_found_ids.join(', ')}." if not_found_ids
raise RecordNotFound.new(error, name, key, ids)
end
end
private
def construct_relation_for_exists(conditions)
conditions = sanitize_forbidden_attributes(conditions)
if distinct_value && offset_value
relation = except(:order).limit!(1)
else
relation = except(:select, :distinct, :order)._select!(ONE_AS_ONE).limit!(1)
end
case conditions
when Array, Hash
relation.where!(conditions) unless conditions.empty?
else
relation.where!(primary_key => conditions) unless conditions == :none
end
relation
end
def apply_join_dependency(eager_loading: group_values.empty?)
join_dependency = construct_join_dependency(
eager_load_values | includes_values, Arel::Nodes::OuterJoin
)
relation = except(:includes, :eager_load, :preload).joins!(join_dependency)
if eager_loading && has_limit_or_offset? && !(
using_limitable_reflections?(join_dependency.reflections) &&
using_limitable_reflections?(
construct_join_dependency(
select_association_list(joins_values).concat(
select_association_list(left_outer_joins_values)
), nil
).reflections
)
)
relation = skip_query_cache_if_necessary do
klass.with_connection do |c|
c.distinct_relation_for_primary_key(relation)
end
end
end
if block_given?
yield relation, join_dependency
else
relation
end
end
def using_limitable_reflections?(reflections)
reflections.none?(&:collection?)
end
def find_with_ids(*ids)
raise UnknownPrimaryKey.new(@klass) if primary_key.nil?
expects_array = if klass.composite_primary_key?
ids.first.first.is_a?(Array)
else
ids.first.is_a?(Array)
end
return [] if expects_array && ids.first.empty?
ids = ids.first if expects_array
ids = ids.compact.uniq
model_name = @klass.name
case ids.size
when 0
error_message = "Couldn't find #{model_name} without an ID"
raise RecordNotFound.new(error_message, model_name, primary_key)
when 1
result = find_one(ids.first)
expects_array ? [ result ] : result
else
find_some(ids)
end
end
def find_one(id)
if ActiveRecord::Base === id
raise ArgumentError, <<-MSG.squish
You are passing an instance of ActiveRecord::Base to `find`.
Please pass the id of the object by calling `.id`.
MSG
end
relation = if klass.composite_primary_key?
where(primary_key.zip(id).to_h)
else
where(primary_key => id)
end
record = relation.take
raise_record_not_found_exception!(id, 0, 1) unless record
record
end
def find_some(ids)
return find_some_ordered(ids) unless order_values.present?
relation = where(primary_key => ids)
relation = relation.select(table[primary_key]) unless select_values.empty?
result = relation.to_a
expected_size =
if limit_value && ids.size > limit_value
limit_value
else
ids.size
end
# 11 ids with limit 3, offset 9 should give 2 results.
if offset_value && (ids.size - offset_value < expected_size)
expected_size = ids.size - offset_value
end
if result.size == expected_size
result
else
raise_record_not_found_exception!(ids, result.size, expected_size)
end
end
def find_some_ordered(ids)
ids = ids.slice(offset_value || 0, limit_value || ids.size) || []
relation = except(:limit, :offset)
relation = relation.where(primary_key => ids)
relation = relation.select(table[primary_key]) unless select_values.empty?
result = relation.records
if result.size == ids.size
result.in_order_of(:id, ids.map { |id| @klass.type_for_attribute(primary_key).cast(id) })
else
raise_record_not_found_exception!(ids, result.size, ids.size)
end
end
def find_take
if loaded?
records.first
else
@take ||= limit(1).records.first
end
end
def find_take_with_limit(limit)
if loaded?
records.take(limit)
else
limit(limit).to_a
end
end
def find_nth(index)
@offsets ||= {}
@offsets[index] ||= find_nth_with_limit(index, 1).first
end
def find_nth_with_limit(index, limit)
if loaded?
records[index, limit] || []
else
relation = ordered_relation
if limit_value
limit = [limit_value - index, limit].min
end
if limit > 0
relation = relation.offset((offset_value || 0) + index) unless index.zero?
relation.limit(limit).to_a
else
[]
end
end
end
def find_nth_from_last(index)
if loaded?
records[-index]
else
relation = ordered_relation
if relation.order_values.empty? || relation.has_limit_or_offset?
relation.records[-index]
else
relation.reverse_order.offset(index - 1).first
end
end
end
def find_last(limit)
limit ? records.last(limit) : records.last
end
def ordered_relation
if order_values.empty? && (implicit_order_column || !query_constraints_list.nil? || primary_key)
order(_order_columns.map { |column| table[column].asc })
else
self
end
end
def _order_columns
oc = []
oc << implicit_order_column if implicit_order_column
oc << query_constraints_list if query_constraints_list
if primary_key && query_constraints_list.nil?
oc << primary_key
end
oc.flatten.uniq.compact
end
end
end