# 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 (1), a list of ids (1, 5, 6), or an array of ids ([5, 6, 10]). # 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) # 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 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 person.visits == 2, add 1 to it, and save, resulting # in two saves of person.visits = 3. By locking the row, the second # transaction has to wait until the first is finished; we get the # expected person.visits == 4. # # 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 nil. # # 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 # 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: # # [#, #, #] # # and not: # # [#, #, #] 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 '5'). # * Array - Finds the record that matches these +find+-style conditions # (such as ['name LIKE ?', "%#{query}%"]). # * Hash - Finds the record that matches these +find+-style conditions # (such as {name: 'David'}). # * +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 name = # 'Jamie'), since it would be sanitized and then queried against # the primary key column, like id = 'name = \'Jamie\''. # # 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) 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) skip_query_cache_if_necessary { connection.select_one(relation.arel, "#{name} Exists?") } ? true : 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, not_found_ids = nil) # :nodoc: conditions = arel.where_sql(@klass) 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, key) 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})." 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 offset_index offset_value || 0 end def construct_relation_for_exists(conditions) conditions = sanitize_forbidden_attributes(conditions) if distinct_value && offset_value relation = 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 && !using_limitable_reflections?(join_dependency.reflections) if has_limit_or_offset? limited_ids = limited_ids_for(relation) limited_ids.empty? ? relation.none! : relation.where!(primary_key => limited_ids) end relation.limit_value = relation.offset_value = nil end if block_given? yield relation, join_dependency else relation end end def limited_ids_for(relation) values = @klass.connection.columns_for_distinct( connection.visitor.compile(arel_attribute(primary_key)), relation.order_values ) relation = relation.except(:select).select(values).distinct! id_rows = skip_query_cache_if_necessary { @klass.connection.select_all(relation.arel, "SQL") } id_rows.map { |row| row[primary_key] } 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 = ids.first.kind_of?(Array) return [] if expects_array && ids.first.empty? ids = ids.flatten.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 = 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 = ordered_relation if limit_value limit = [limit_value - index, limit].min end if limit > 0 relation = relation.offset(offset_index + 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 equal?(relation) || has_limit_or_offset? relation.records[-index] else relation.last(index)[-index] end end end def find_last(limit) limit ? records.last(limit) : records.last end def ordered_relation if order_values.empty? && (implicit_order_column || primary_key) order(arel_attribute(implicit_order_column || primary_key).asc) else self end end end end