module ActiveRecord # = Active Record \Relation class Relation MULTI_VALUE_METHODS = [:includes, :eager_load, :preload, :select, :group, :order, :joins, :left_joins, :left_outer_joins, :references, :extending, :unscope] SINGLE_VALUE_METHODS = [:limit, :offset, :lock, :readonly, :reordering, :reverse_order, :distinct, :create_with] CLAUSE_METHODS = [:where, :having, :from] INVALID_METHODS_FOR_DELETE_ALL = [:limit, :distinct, :offset, :group, :having] VALUE_METHODS = MULTI_VALUE_METHODS + SINGLE_VALUE_METHODS + CLAUSE_METHODS include Enumerable include FinderMethods, Calculations, SpawnMethods, QueryMethods, Batches, Explain, Delegation attr_reader :table, :klass, :loaded, :predicate_builder alias :model :klass alias :loaded? :loaded def initialize(klass, table, predicate_builder, values = {}) @klass = klass @table = table @values = values @offsets = {} @loaded = false @predicate_builder = predicate_builder end def initialize_copy(other) @values = @values.dup reset end def insert(values) # :nodoc: primary_key_value = nil if primary_key && Hash === values primary_key_value = values[values.keys.find { |k| k.name == primary_key }] if !primary_key_value && klass.prefetch_primary_key? primary_key_value = klass.next_sequence_value values[arel_attribute(klass.primary_key)] = primary_key_value end end im = arel.create_insert im.into @table substitutes, binds = substitute_values values if values.empty? # empty insert im.values = Arel.sql(connection.empty_insert_statement_value) else im.insert substitutes end @klass.connection.insert( im, "SQL", primary_key || false, primary_key_value, nil, binds) end def _update_record(values, id, id_was) # :nodoc: substitutes, binds = substitute_values values scope = @klass.unscoped if @klass.finder_needs_type_condition? scope.unscope!(where: @klass.inheritance_column) end relation = scope.where(@klass.primary_key => (id_was || id)) bvs = binds + relation.bound_attributes um = relation .arel .compile_update(substitutes, @klass.primary_key) @klass.connection.update( um, "SQL", bvs, ) end def substitute_values(values) # :nodoc: binds = [] substitutes = [] values.each do |arel_attr, value| binds.push QueryAttribute.new(arel_attr.name, value, klass.type_for_attribute(arel_attr.name)) substitutes.push [arel_attr, Arel::Nodes::BindParam.new] end [substitutes, binds] end def arel_attribute(name) # :nodoc: klass.arel_attribute(name, table) end # Initializes new record from relation while maintaining the current # scope. # # Expects arguments in the same format as {ActiveRecord::Base.new}[rdoc-ref:Core.new]. # # users = User.where(name: 'DHH') # user = users.new # => # # # You can also pass a block to new with the new record as argument: # # user = users.new { |user| user.name = 'Oscar' } # user.name # => Oscar def new(*args, &block) scoping { @klass.new(*args, &block) } end alias build new # Tries to create a new record with the same scoped attributes # defined in the relation. Returns the initialized object if validation fails. # # Expects arguments in the same format as # {ActiveRecord::Base.create}[rdoc-ref:Persistence::ClassMethods#create]. # # ==== Examples # # users = User.where(name: 'Oscar') # users.create # => # # # users.create(name: 'fxn') # users.create # => # # # users.create { |user| user.name = 'tenderlove' } # # => # # # users.create(name: nil) # validation on name # # => # def create(*args, &block) scoping { @klass.create(*args, &block) } end # Similar to #create, but calls # {create!}[rdoc-ref:Persistence::ClassMethods#create!] # on the base class. Raises an exception if a validation error occurs. # # Expects arguments in the same format as # {ActiveRecord::Base.create!}[rdoc-ref:Persistence::ClassMethods#create!]. def create!(*args, &block) scoping { @klass.create!(*args, &block) } end def first_or_create(attributes = nil, &block) # :nodoc: first || create(attributes, &block) end def first_or_create!(attributes = nil, &block) # :nodoc: first || create!(attributes, &block) end def first_or_initialize(attributes = nil, &block) # :nodoc: first || new(attributes, &block) end # Finds the first record with the given attributes, or creates a record # with the attributes if one is not found: # # # Find the first user named "Penélope" or create a new one. # User.find_or_create_by(first_name: 'Penélope') # # => # # # # Find the first user named "Penélope" or create a new one. # # We already have one so the existing record will be returned. # User.find_or_create_by(first_name: 'Penélope') # # => # # # # Find the first user named "Scarlett" or create a new one with # # a particular last name. # User.create_with(last_name: 'Johansson').find_or_create_by(first_name: 'Scarlett') # # => # # # This method accepts a block, which is passed down to #create. The last example # above can be alternatively written this way: # # # Find the first user named "Scarlett" or create a new one with a # # different last name. # User.find_or_create_by(first_name: 'Scarlett') do |user| # user.last_name = 'Johansson' # end # # => # # # This method always returns a record, but if creation was attempted and # failed due to validation errors it won't be persisted, you get what # #create returns in such situation. # # Please note *this method is not atomic*, it runs first a SELECT, and if # there are no results an INSERT is attempted. If there are other threads # or processes there is a race condition between both calls and it could # be the case that you end up with two similar records. # # Whether that is a problem or not depends on the logic of the # application, but in the particular case in which rows have a UNIQUE # constraint an exception may be raised, just retry: # # begin # CreditAccount.transaction(requires_new: true) do # CreditAccount.find_or_create_by(user_id: user.id) # end # rescue ActiveRecord::RecordNotUnique # retry # end # def find_or_create_by(attributes, &block) find_by(attributes) || create(attributes, &block) end # Like #find_or_create_by, but calls # {create!}[rdoc-ref:Persistence::ClassMethods#create!] so an exception # is raised if the created record is invalid. def find_or_create_by!(attributes, &block) find_by(attributes) || create!(attributes, &block) end # Like #find_or_create_by, but calls {new}[rdoc-ref:Core#new] # instead of {create}[rdoc-ref:Persistence::ClassMethods#create]. def find_or_initialize_by(attributes, &block) find_by(attributes) || new(attributes, &block) end # Runs EXPLAIN on the query or queries triggered by this relation and # returns the result as a string. The string is formatted imitating the # ones printed by the database shell. # # Note that this method actually runs the queries, since the results of some # are needed by the next ones when eager loading is going on. # # Please see further details in the # {Active Record Query Interface guide}[http://guides.rubyonrails.org/active_record_querying.html#running-explain]. def explain exec_explain(collecting_queries_for_explain { exec_queries }) end # Converts relation objects to Array. def to_a records.dup end def records # :nodoc: load @records end # Serializes the relation objects Array. def encode_with(coder) coder.represent_seq(nil, records) end # Returns size of the records. def size loaded? ? @records.length : count(:all) end # Returns true if there are no records. def empty? return @records.empty? if loaded? limit_value == 0 || !exists? end # Returns true if there are no records. def none? return super if block_given? empty? end # Returns true if there are any records. def any? return super if block_given? !empty? end # Returns true if there is exactly one record. def one? return super if block_given? limit_value ? records.one? : size == 1 end # Returns true if there is more than one record. def many? return super if block_given? limit_value ? records.many? : size > 1 end # Returns a cache key that can be used to identify the records fetched by # this query. The cache key is built with a fingerprint of the sql query, # the number of records matched by the query and a timestamp of the last # updated record. When a new record comes to match the query, or any of # the existing records is updated or deleted, the cache key changes. # # Product.where("name like ?", "%Cosmic Encounter%").cache_key # # => "products/query-1850ab3d302391b85b8693e941286659-1-20150714212553907087000" # # If the collection is loaded, the method will iterate through the records # to generate the timestamp, otherwise it will trigger one SQL query like: # # SELECT COUNT(*), MAX("products"."updated_at") FROM "products" WHERE (name like '%Cosmic Encounter%') # # You can also pass a custom timestamp column to fetch the timestamp of the # last updated record. # # Product.where("name like ?", "%Game%").cache_key(:last_reviewed_at) # # You can customize the strategy to generate the key on a per model basis # overriding ActiveRecord::Base#collection_cache_key. def cache_key(timestamp_column = :updated_at) @cache_keys ||= {} @cache_keys[timestamp_column] ||= @klass.collection_cache_key(self, timestamp_column) end # Scope all queries to the current scope. # # Comment.where(post_id: 1).scoping do # Comment.first # end # # => SELECT "comments".* FROM "comments" WHERE "comments"."post_id" = 1 ORDER BY "comments"."id" ASC LIMIT 1 # # Please check unscoped if you want to remove all previous scopes (including # the default_scope) during the execution of a block. def scoping previous, klass.current_scope = klass.current_scope, self yield ensure klass.current_scope = previous end # Updates all records in the current relation with details given. This method constructs a single SQL UPDATE # statement and sends it straight to the database. It does not instantiate the involved models and it does not # trigger Active Record callbacks or validations. However, values passed to #update_all will still go through # Active Record's normal type casting and serialization. # # ==== Parameters # # * +updates+ - A string, array, or hash representing the SET part of an SQL statement. # # ==== Examples # # # Update all customers with the given attributes # Customer.update_all wants_email: true # # # Update all books with 'Rails' in their title # Book.where('title LIKE ?', '%Rails%').update_all(author: 'David') # # # Update all books that match conditions, but limit it to 5 ordered by date # Book.where('title LIKE ?', '%Rails%').order(:created_at).limit(5).update_all(author: 'David') # # # Update all invoices and set the number column to its id value. # Invoice.update_all('number = id') def update_all(updates) raise ArgumentError, "Empty list of attributes to change" if updates.blank? stmt = Arel::UpdateManager.new stmt.set Arel.sql(@klass.send(:sanitize_sql_for_assignment, updates)) stmt.table(table) if has_join_values? @klass.connection.join_to_update(stmt, arel, arel_attribute(primary_key)) else stmt.key = arel_attribute(primary_key) stmt.take(arel.limit) stmt.order(*arel.orders) stmt.wheres = arel.constraints end @klass.connection.update stmt, "SQL", bound_attributes end # Updates an object (or multiple objects) and saves it to the database, if validations pass. # The resulting object is returned whether the object was saved successfully to the database or not. # # ==== Parameters # # * +id+ - This should be the id or an array of ids to be updated. # * +attributes+ - This should be a hash of attributes or an array of hashes. # # ==== Examples # # # Updates one record # Person.update(15, user_name: 'Samuel', group: 'expert') # # # Updates multiple records # people = { 1 => { "first_name" => "David" }, 2 => { "first_name" => "Jeremy" } } # Person.update(people.keys, people.values) # # # Updates multiple records from the result of a relation # people = Person.where(group: 'expert') # people.update(group: 'masters') # # Note: Updating a large number of records will run an # UPDATE query for each record, which may cause a performance # issue. So if it is not needed to run callbacks for each update, it is # preferred to use #update_all for updating all records using # a single query. def update(id = :all, attributes) if id.is_a?(Array) id.map.with_index { |one_id, idx| update(one_id, attributes[idx]) } elsif id == :all records.each { |record| record.update(attributes) } else if ActiveRecord::Base === id raise ArgumentError, <<-MSG.squish You are passing an instance of ActiveRecord::Base to `update`. Please pass the id of the object by calling `.id`. MSG end object = find(id) object.update(attributes) object end end # Destroys the records by instantiating each # record and calling its {#destroy}[rdoc-ref:Persistence#destroy] method. # Each object's callbacks are executed (including :dependent association options). # Returns the collection of objects that were destroyed; each will be frozen, to # reflect that no changes should be made (since they can't be persisted). # # Note: Instantiation, callback execution, and deletion of each # record can be time consuming when you're removing many records at # once. It generates at least one SQL +DELETE+ query per record (or # possibly more, to enforce your callbacks). If you want to delete many # rows quickly, without concern for their associations or callbacks, use # #delete_all instead. # # ==== Examples # # Person.where(age: 0..18).destroy_all def destroy_all records.each(&:destroy).tap { reset } end # Destroy an object (or multiple objects) that has the given id. The object is instantiated first, # therefore all callbacks and filters are fired off before the object is deleted. This method is # less efficient than #delete but allows cleanup methods and other actions to be run. # # This essentially finds the object (or multiple objects) with the given id, creates a new object # from the attributes, and then calls destroy on it. # # ==== Parameters # # * +id+ - Can be either an Integer or an Array of Integers. # # ==== Examples # # # Destroy a single object # Todo.destroy(1) # # # Destroy multiple objects # todos = [1,2,3] # Todo.destroy(todos) def destroy(id) if id.is_a?(Array) id.map { |one_id| destroy(one_id) } else find(id).destroy end end # Deletes the records without instantiating the records # first, and hence not calling the {#destroy}[rdoc-ref:Persistence#destroy] # method nor invoking callbacks. # This is a single SQL DELETE statement that goes straight to the database, much more # efficient than #destroy_all. Be careful with relations though, in particular # :dependent rules defined on associations are not honored. Returns the # number of rows affected. # # Post.where(person_id: 5).where(category: ['Something', 'Else']).delete_all # # Both calls delete the affected posts all at once with a single DELETE statement. # If you need to destroy dependent associations or call your before_* or # +after_destroy+ callbacks, use the #destroy_all method instead. # # If an invalid method is supplied, #delete_all raises an ActiveRecordError: # # Post.limit(100).delete_all # # => ActiveRecord::ActiveRecordError: delete_all doesn't support limit def delete_all invalid_methods = INVALID_METHODS_FOR_DELETE_ALL.select do |method| value = get_value(method) SINGLE_VALUE_METHODS.include?(method) ? value : value.any? end if invalid_methods.any? raise ActiveRecordError.new("delete_all doesn't support #{invalid_methods.join(', ')}") end stmt = Arel::DeleteManager.new stmt.from(table) if has_join_values? @klass.connection.join_to_delete(stmt, arel, arel_attribute(primary_key)) else stmt.wheres = arel.constraints end affected = @klass.connection.delete(stmt, "SQL", bound_attributes) reset affected end # Deletes the row with a primary key matching the +id+ argument, using a # SQL +DELETE+ statement, and returns the number of rows deleted. Active # Record objects are not instantiated, so the object's callbacks are not # executed, including any :dependent association options. # # You can delete multiple rows at once by passing an Array of ids. # # Note: Although it is often much faster than the alternative, # #destroy, skipping callbacks might bypass business logic in # your application that ensures referential integrity or performs other # essential jobs. # # ==== Examples # # # Delete a single row # Todo.delete(1) # # # Delete multiple rows # Todo.delete([2,3,4]) def delete(id_or_array) where(primary_key => id_or_array).delete_all end # Causes the records to be loaded from the database if they have not # been loaded already. You can use this if for some reason you need # to explicitly load some records before actually using them. The # return value is the relation itself, not the records. # # Post.where(published: true).load # => # def load(&block) exec_queries(&block) unless loaded? self end # Forces reloading of relation. def reload reset load end def reset @last = @to_sql = @order_clause = @scope_for_create = @arel = @loaded = nil @should_eager_load = @join_dependency = nil @records = [].freeze @offsets = {} self end # Returns sql statement for the relation. # # User.where(name: 'Oscar').to_sql # # => SELECT "users".* FROM "users" WHERE "users"."name" = 'Oscar' def to_sql @to_sql ||= begin relation = self if eager_loading? find_with_associations { |rel| relation = rel } end conn = klass.connection conn.unprepared_statement { conn.to_sql(relation.arel, relation.bound_attributes) } end end # Returns a hash of where conditions. # # User.where(name: 'Oscar').where_values_hash # # => {name: "Oscar"} def where_values_hash(relation_table_name = table_name) where_clause.to_h(relation_table_name) end def scope_for_create @scope_for_create ||= where_values_hash.merge(create_with_value) end # Returns true if relation needs eager loading. def eager_loading? @should_eager_load ||= eager_load_values.any? || includes_values.any? && (joined_includes_values.any? || references_eager_loaded_tables?) end # Joins that are also marked for preloading. In which case we should just eager load them. # Note that this is a naive implementation because we could have strings and symbols which # represent the same association, but that aren't matched by this. Also, we could have # nested hashes which partially match, e.g. { a: :b } & { a: [:b, :c] } def joined_includes_values includes_values & joins_values end # Compares two relations for equality. def ==(other) case other when Associations::CollectionProxy, AssociationRelation self == other.records when Relation other.to_sql == to_sql when Array records == other end end def pretty_print(q) q.pp(records) end # Returns true if relation is blank. def blank? records.blank? end def values @values.dup end def inspect entries = records.take([limit_value, 11].compact.min).map!(&:inspect) entries[10] = "..." if entries.size == 11 "#<#{self.class.name} [#{entries.join(', ')}]>" end protected def load_records(records) @records = records.freeze @loaded = true end private def has_join_values? joins_values.any? || left_outer_joins_values.any? end def exec_queries(&block) @records = eager_loading? ? find_with_associations.freeze : @klass.find_by_sql(arel, bound_attributes, &block).freeze preload = preload_values preload += includes_values unless eager_loading? preloader = nil preload.each do |associations| preloader ||= build_preloader preloader.preload @records, associations end @records.each(&:readonly!) if readonly_value @loaded = true @records end def build_preloader ActiveRecord::Associations::Preloader.new end def references_eager_loaded_tables? joined_tables = arel.join_sources.map do |join| if join.is_a?(Arel::Nodes::StringJoin) tables_in_string(join.left) else [join.left.table_name, join.left.table_alias] end end joined_tables += [table.name, table.table_alias] # always convert table names to downcase as in Oracle quoted table names are in uppercase joined_tables = joined_tables.flatten.compact.map(&:downcase).uniq (references_values - joined_tables).any? end def tables_in_string(string) return [] if string.blank? # always convert table names to downcase as in Oracle quoted table names are in uppercase # ignore raw_sql_ that is used by Oracle adapter as alias for limit/offset subqueries string.scan(/([a-zA-Z_][.\w]+).?\./).flatten.map(&:downcase).uniq - ["raw_sql_"] end end end