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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 (1), a list of ids (1, 5, 6), or an array of ids ([5, 6, 10]).
# If one or more records can not be found for the requested ids, then RecordNotFound will be raised. If the primary key
# is an integer, find by id coerces its arguments 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)
# Person.find([1]) # returns an array for the object with ID = 1
# Person.where("administrator = 1").order("created_on DESC").find(1)
#
# NOTE: The returned records may not be in the same order as the ids you
# provide since database rows are unordered. You will need to provide an explicit QueryMethods#order
# option if you want the results to be sorted.
#
# ==== 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.
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
rescue ::RangeError
nil
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!
rescue ::RangeError
raise RecordNotFound.new("Couldn't find #{@klass.name} with an out of range value",
@klass.name)
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
# 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? || limit_value
result = limit(limit || 1)
result.order!(arel_attribute(primary_key)) if order_values.empty? && primary_key
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 +find+-style conditions
# (such as <tt>['name LIKE ?', "%#{query}%"]</tt>).
# * Hash - Finds the record that matches these +find+-style conditions
# (such as <tt>{name: 'David'}</tt>).
# * +false+ - Returns always +false+.
# * No args - Returns +false+ if the table 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?
def exists?(conditions = :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
relation = apply_join_dependency(self, construct_join_dependency(eager_loading: false))
return false if ActiveRecord::NullRelation === relation
relation = relation.except(:select, :distinct).select(ONE_AS_ONE).limit(1)
case conditions
when Array, Hash
relation = relation.where(conditions)
else
unless conditions == :none
relation = relation.where(primary_key => conditions)
end
end
connection.select_value(relation, "#{name} Exists", relation.bound_attributes) ? true : false
rescue ::RangeError
false
end
# 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) # :nodoc:
conditions = arel.where_sql(@klass.arel_engine)
conditions = " [#{conditions}]" if conditions
name = @klass.name
if ids.nil?
error = "Couldn't find #{name}"
error << " with#{conditions}" if conditions
raise RecordNotFound.new(error, name)
elsif Array(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})"
raise RecordNotFound.new(error, name, primary_key, ids)
end
end
private
def offset_index
offset_value || 0
end
def find_with_associations
# NOTE: the JoinDependency constructed here needs to know about
# any joins already present in `self`, so pass them in
#
# failing to do so means that in cases like activerecord/test/cases/associations/inner_join_association_test.rb:136
# incorrect SQL is generated. In that case, the join dependency for
# SpecialCategorizations is constructed without knowledge of the
# preexisting join in joins_values to categorizations (by way of
# the `has_many :through` for categories).
#
join_dependency = construct_join_dependency(joins_values)
aliases = join_dependency.aliases
relation = select aliases.columns
relation = apply_join_dependency(relation, join_dependency)
if block_given?
yield relation
else
if ActiveRecord::NullRelation === relation
[]
else
arel = relation.arel
rows = connection.select_all(arel, "SQL", relation.bound_attributes)
join_dependency.instantiate(rows, aliases)
end
end
end
def construct_join_dependency(joins = [], eager_loading: true)
including = eager_load_values + includes_values
ActiveRecord::Associations::JoinDependency.new(@klass, including, joins, eager_loading: eager_loading)
end
def construct_relation_for_association_calculations
apply_join_dependency(self, construct_join_dependency(joins_values))
end
def apply_join_dependency(relation, join_dependency)
relation = relation.except(:includes, :eager_load, :preload)
relation = relation.joins join_dependency
if using_limitable_reflections?(join_dependency.reflections)
relation
else
if relation.limit_value
limited_ids = limited_ids_for(relation)
limited_ids.empty? ? relation.none! : relation.where!(primary_key => limited_ids)
end
relation.except(:limit, :offset)
end
end
def limited_ids_for(relation)
values = @klass.connection.columns_for_distinct(
"#{quoted_table_name}.#{quoted_primary_key}", relation.order_values)
relation = relation.except(:select).select(values).distinct!
arel = relation.arel
id_rows = @klass.connection.select_all(arel, "SQL", relation.bound_attributes)
id_rows.map { |row| row[primary_key] }
end
def using_limitable_reflections?(reflections)
reflections.none?(&:collection?)
end
private
def find_with_ids(*ids)
raise UnknownPrimaryKey.new(@klass) if primary_key.nil?
expects_array = ids.first.kind_of?(Array)
return ids.first if expects_array && ids.first.empty?
ids = ids.flatten.compact.uniq
case ids.size
when 0
raise RecordNotFound, "Couldn't find #{@klass.name} without an ID"
when 1
result = find_one(ids.first)
expects_array ? [ result ] : result
else
find_some(ids)
end
rescue ::RangeError
raise RecordNotFound, "Couldn't find #{@klass.name} with an out of range ID"
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 = where(primary_key => id)
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?
result = where(primary_key => ids).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) || []
result = except(:limit, :offset).where(primary_key => ids).records
if result.size == ids.size
pk_type = @klass.type_for_attribute(primary_key)
records_by_id = result.index_by(&:id)
ids.map { |id| records_by_id.fetch(pk_type.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[offset_index + index] ||= find_nth_with_limit(index, 1).first
end
def find_nth_with_limit(index, limit)
if loaded?
records[index, limit] || []
else
relation = if order_values.empty? && primary_key
order(arel_attribute(primary_key).asc)
else
self
end
relation = relation.offset(offset_index + index) unless index.zero?
relation.limit(limit).to_a
end
end
def find_nth_from_last(index)
if loaded?
records[-index]
else
relation = if order_values.empty? && primary_key
order(arel_attribute(primary_key).asc)
else
self
end
relation.to_a[-index]
# TODO: can be made more performant on large result sets by
# for instance, last(index)[-index] (which would require
# refactoring the last(n) finder method to make test suite pass),
# or by using a combination of reverse_order, limit, and offset,
# e.g., reverse_order.offset(index-1).first
end
end
def find_last(limit)
limit ? records.last(limit) : records.last
end
end
end