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Diffstat (limited to 'activerecord/lib/active_record/relation/finder_methods.rb')
| -rw-r--r-- | activerecord/lib/active_record/relation/finder_methods.rb | 560 |
1 files changed, 560 insertions, 0 deletions
diff --git a/activerecord/lib/active_record/relation/finder_methods.rb b/activerecord/lib/active_record/relation/finder_methods.rb new file mode 100644 index 0000000000..dc03b196f4 --- /dev/null +++ b/activerecord/lib/active_record/relation/finder_methods.rb @@ -0,0 +1,560 @@ +# 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 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 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. + 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, @klass.primary_key) + 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? || 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 +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 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) + 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_value(relation.arel, "#{name} Exists") } ? 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, 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) + relation = except(:select, :distinct, :order)._select!(ONE_AS_ONE).limit!(1) + + case conditions + when Array, Hash + relation.where!(conditions) unless conditions.empty? + else + relation.where!(primary_key => conditions) unless conditions == :none + end + + relation + end + + def construct_join_dependency(associations) + ActiveRecord::Associations::JoinDependency.new( + klass, table, associations + ) + end + + def apply_join_dependency(eager_loading: group_values.empty?) + join_dependency = construct_join_dependency(eager_load_values + includes_values) + 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 + rescue ::RangeError + error_message = "Couldn't find #{model_name} with an out of range ID" + raise RecordNotFound.new(error_message, model_name, primary_key, ids) + 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 |