diff options
Diffstat (limited to 'activerecord/lib/active_record/relation/finder_methods.rb')
| -rw-r--r-- | activerecord/lib/active_record/relation/finder_methods.rb | 162 |
1 files changed, 101 insertions, 61 deletions
diff --git a/activerecord/lib/active_record/relation/finder_methods.rb b/activerecord/lib/active_record/relation/finder_methods.rb index 72e9272cd7..0132a02f83 100644 --- a/activerecord/lib/active_record/relation/finder_methods.rb +++ b/activerecord/lib/active_record/relation/finder_methods.rb @@ -1,5 +1,7 @@ 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 no record can be found for all of the listed ids, then RecordNotFound will be raised. If the primary key # is an integer, find by id coerces its arguments using +to_i+. @@ -11,9 +13,11 @@ module ActiveRecord # Person.find([1]) # returns an array for the object with ID = 1 # Person.where("administrator = 1").order("created_on DESC").find(1) # - # Note that returned records may not be in the same order as the ids you - # provide since database rows are unordered. Give an explicit <tt>order</tt> - # to ensure the results are sorted. + # <tt>ActiveRecord::RecordNotFound</tt> will be raised if one or more ids are not found. + # + # NOTE: The returned records may not be in the same order as the ids you + # provide since database rows are unordered. You'd need to provide an explicit <tt>order</tt> + # option if you want the results are sorted. # # ==== Find with lock # @@ -28,6 +32,34 @@ module ActiveRecord # 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.where(name: 'Spartacus', rating: 4).first_or_initialize + # # returns the first item or returns a new instance (requires you call .save to persist against the database). + # + # Person.where(name: 'Spartacus', rating: 4).first_or_create + # # returns the first item or creates it and returns it, available since Rails 3.2.1. + # + # ==== 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, available since Rails 3.2.1. + # + # Person.where(name: 'Spartacus', rating: 4).pluck(:field1, :field2) + # # returns an Array of the required fields, available since Rails 3.1. def find(*args) if block_given? to_a.find { |*block_args| yield(*block_args) } @@ -79,13 +111,22 @@ module ActiveRecord # 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 LIMIT 3 + # + # ==== Rails 3 + # + # Person.first # SELECT "people".* FROM "people" LIMIT 1 + # + # NOTE: Rails 3 may not order this query by the primary key and the order + # will depend on the database implementation. In order to ensure that behavior, + # use <tt>User.order(:id).first</tt> instead. + # + # ==== Rails 4 + # + # Person.first # SELECT "people".* FROM "people" ORDER BY "people"."id" ASC LIMIT 1 + # def first(limit = nil) if limit - if order_values.empty? && primary_key - order(arel_table[primary_key].asc).limit(limit).to_a - else - limit(limit).to_a - end + find_first_with_limit(limit) else find_first end @@ -130,21 +171,21 @@ module ActiveRecord last or raise RecordNotFound end - # Returns truthy if a record exists in the table that matches the +id+ or - # conditions given, or falsy otherwise. The argument can take six forms: + # 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>['color = ?', 'red']</tt>). + # (such as <tt>['name LIKE ?', "%#{query}%"]</tt>). # * Hash - Finds the record that matches these +find+-style conditions - # (such as <tt>{color: 'red'}</tt>). + # (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. + # For more information about specifying conditions as a hash or array, + # see the Conditions section in the introduction to <tt>ActiveRecord::Base</tt>. # # 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 @@ -160,9 +201,10 @@ module ActiveRecord conditions = conditions.id if Base === conditions return false if !conditions - join_dependency = construct_join_dependency_for_association_find - relation = construct_relation_for_association_find(join_dependency) - relation = relation.except(:select, :order).select("1 AS one").limit(1) + relation = construct_relation_for_association_find(construct_join_dependency) + return false if ActiveRecord::NullRelation === relation + + relation = relation.except(:select, :order).select(ONE_AS_ONE).limit(1) case conditions when Array, Hash @@ -171,9 +213,7 @@ module ActiveRecord relation = relation.where(table[primary_key].eq(conditions)) if conditions != :none end - connection.select_value(relation, "#{name} Exists", relation.bind_values) - rescue ThrowResult - false + connection.select_value(relation, "#{name} Exists", relation.bind_values) ? true : false end # This method is called whenever no records are found with either a single @@ -198,63 +238,64 @@ module ActiveRecord raise RecordNotFound, error end - protected + private def find_with_associations - join_dependency = construct_join_dependency_for_association_find + join_dependency = construct_join_dependency relation = construct_relation_for_association_find(join_dependency) - rows = connection.select_all(relation, 'SQL', relation.bind_values.dup) - join_dependency.instantiate(rows) - rescue ThrowResult - [] + if ActiveRecord::NullRelation === relation + [] + else + rows = connection.select_all(relation.arel, 'SQL', relation.bind_values.dup) + join_dependency.instantiate(rows) + end end - def construct_join_dependency_for_association_find + def construct_join_dependency(joins = []) including = (eager_load_values + includes_values).uniq - ActiveRecord::Associations::JoinDependency.new(@klass, including, []) + ActiveRecord::Associations::JoinDependency.new(@klass, including, joins) end def construct_relation_for_association_calculations - including = (eager_load_values + includes_values).uniq - join_dependency = ActiveRecord::Associations::JoinDependency.new(@klass, including, arel.froms.first) - relation = except(:includes, :eager_load, :preload) - apply_join_dependency(relation, join_dependency) + apply_join_dependency(self, construct_join_dependency(arel.froms.first)) end def construct_relation_for_association_find(join_dependency) - relation = except(:includes, :eager_load, :preload, :select).select(join_dependency.columns) + relation = except(:select).select(join_dependency.columns) apply_join_dependency(relation, join_dependency) end def apply_join_dependency(relation, join_dependency) - join_dependency.join_associations.each do |association| - relation = association.join_relation(relation) - end - - limitable_reflections = using_limitable_reflections?(join_dependency.reflections) + relation = relation.except(:includes, :eager_load, :preload) + relation = join_dependency.join_relation(relation) - if !limitable_reflections && relation.limit_value - limited_id_condition = construct_limited_ids_condition(relation.except(:select)) - relation = relation.where(limited_id_condition) + 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!(table[primary_key].in(limited_ids)) + end + relation.except(:limit, :offset) end - - relation = relation.except(:limit, :offset) unless limitable_reflections - - relation end - def construct_limited_ids_condition(relation) - orders = relation.order_values.map { |val| val.presence }.compact - values = @klass.connection.distinct("#{quoted_table_name}.#{primary_key}", orders) + def limited_ids_for(relation) + values = @klass.connection.columns_for_distinct( + "#{quoted_table_name}.#{quoted_primary_key}", relation.order_values) - relation = relation.dup.select(values) + relation = relation.except(:select).select(values).distinct! id_rows = @klass.connection.select_all(relation.arel, 'SQL', relation.bind_values) - ids_array = id_rows.map {|row| row[primary_key]} + id_rows.map {|row| row[primary_key]} + end - ids_array.empty? ? raise(ThrowResult) : table[primary_key].in(ids_array) + def using_limitable_reflections?(reflections) + reflections.none? { |r| r.collection? } end + protected + def find_with_ids(*ids) expects_array = ids.first.kind_of?(Array) return ids.first if expects_array && ids.first.empty? @@ -320,12 +361,15 @@ module ActiveRecord if loaded? @records.first else - @first ||= - if with_default_scope.order_values.empty? && primary_key - order(arel_table[primary_key].asc).limit(1).to_a.first - else - limit(1).to_a.first - end + @first ||= find_first_with_limit(1).first + end + end + + def find_first_with_limit(limit) + if order_values.empty? && primary_key + order(arel_table[primary_key].asc).limit(limit).to_a + else + limit(limit).to_a end end @@ -341,9 +385,5 @@ module ActiveRecord end end end - - def using_limitable_reflections?(reflections) - reflections.none? { |r| r.collection? } - end end end |