# frozen_string_literal: true module ActiveRecord # = Active Record \Relation class Relation MULTI_VALUE_METHODS = [:includes, :eager_load, :preload, :select, :group, :order, :joins, :left_outer_joins, :references, :extending, :unscope] SINGLE_VALUE_METHODS = [:limit, :offset, :lock, :readonly, :reordering, :reverse_order, :distinct, :create_with, :skip_query_cache] CLAUSE_METHODS = [:where, :having, :from] INVALID_METHODS_FOR_DELETE_ALL = [:distinct, :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 attr_accessor :skip_preloading_value alias :model :klass alias :loaded? :loaded alias :locked? :lock_value def initialize(klass, table: klass.arel_table, predicate_builder: klass.predicate_builder, values: {}) @klass = klass @table = table @values = values @offsets = {} @loaded = false @predicate_builder = predicate_builder @delegate_to_klass = false end def initialize_copy(other) @values = @values.dup reset 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(attributes = nil, &block) scoping { klass.new(scope_for_create(attributes), &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(attributes = nil, &block) if attributes.is_a?(Array) attributes.collect { |attr| create(attr, &block) } else scoping { klass.create(scope_for_create(attributes), &block) } end 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!(attributes = nil, &block) if attributes.is_a?(Array) attributes.collect { |attr| create!(attr, &block) } else scoping { klass.create!(scope_for_create(attributes), &block) } end 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. # # If this might be a problem for your application, please see #create_or_find_by. 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 # Attempts to create a record with the given attributes in a table that has a unique constraint # on one or several of its columns. If a row already exists with one or several of these # unique constraints, the exception such an insertion would normally raise is caught, # and the existing record with those attributes is found using #find_by. # # This is similar to #find_or_create_by, but avoids the problem of stale reads between the SELECT # and the INSERT, as that method needs to first query the table, then attempt to insert a row # if none is found. # # There are several drawbacks to #create_or_find_by, though: # # * The underlying table must have the relevant columns defined with unique constraints. # * A unique constraint violation may be triggered by only one, or at least less than all, # of the given attributes. This means that the subsequent #find_by may fail to find a # matching record, which will then raise an ActiveRecord::RecordNotFound exception, # rather than a record with the given attributes. # * While we avoid the race condition between SELECT -> INSERT from #find_or_create_by, # we actually have another race condition between INSERT -> SELECT, which can be triggered # if a DELETE between those two statements is run by another client. But for most applications, # that's a significantly less likely condition to hit. # * It relies on exception handling to handle control flow, which may be marginally slower. # # This method will return a record if all given attributes are covered by unique constraints # (unless the INSERT -> DELETE -> SELECT race condition is triggered), but if creation was attempted # and failed due to validation errors it won't be persisted, you get what #create returns in # such situation. def create_or_find_by(attributes, &block) transaction(requires_new: true) { create(attributes, &block) } rescue ActiveRecord::RecordNotUnique find_by!(attributes) end # Like #create_or_find_by, but calls # {create!}[rdoc-ref:Persistence::ClassMethods#create!] so an exception # is raised if the created record is invalid. def create_or_find_by!(attributes, &block) transaction(requires_new: true) { create!(attributes, &block) } rescue ActiveRecord::RecordNotUnique find_by!(attributes) 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_ary records.dup end alias to_a to_ary 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? !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(true), self yield ensure klass.current_scope = previous end def _exec_scope(*args, &block) # :nodoc: @delegate_to_klass = true instance_exec(*args, &block) || self ensure @delegate_to_klass = false 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? if eager_loading? relation = apply_join_dependency return relation.update_all(updates) end stmt = Arel::UpdateManager.new stmt.set Arel.sql(@klass.sanitize_sql_for_assignment(updates)) stmt.table(table) if has_join_values? || offset_value @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, "#{@klass} Update All" end # Touches all records in the current relation without instantiating records first with the updated_at/on attributes # set to the current time or the time specified. # This method can be passed attribute names and an optional time argument. # If attribute names are passed, they are updated along with updated_at/on attributes. # If no time argument is passed, the current time is used as default. # # === Examples # # # Touch all records # Person.all.touch_all # # => "UPDATE \"people\" SET \"updated_at\" = '2018-01-04 22:55:23.132670'" # # # Touch multiple records with a custom attribute # Person.all.touch_all(:created_at) # # => "UPDATE \"people\" SET \"updated_at\" = '2018-01-04 22:55:23.132670', \"created_at\" = '2018-01-04 22:55:23.132670'" # # # Touch multiple records with a specified time # Person.all.touch_all(time: Time.new(2020, 5, 16, 0, 0, 0)) # # => "UPDATE \"people\" SET \"updated_at\" = '2020-05-16 00:00:00'" # # # Touch records with scope # Person.where(name: 'David').touch_all # # => "UPDATE \"people\" SET \"updated_at\" = '2018-01-04 22:55:23.132670' WHERE \"people\".\"name\" = 'David'" def touch_all(*names, time: nil) updates = touch_attributes_with_time(*names, time: time) if klass.locking_enabled? quoted_locking_column = connection.quote_column_name(klass.locking_column) updates = sanitize_sql_for_assignment(updates) + ", #{quoted_locking_column} = COALESCE(#{quoted_locking_column}, 0) + 1" end update_all(updates) 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 # 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.distinct.delete_all # # => ActiveRecord::ActiveRecordError: delete_all doesn't support distinct 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 if eager_loading? relation = apply_join_dependency return relation.delete_all end stmt = Arel::DeleteManager.new stmt.from(table) if has_join_values? || has_limit_or_offset? @klass.connection.join_to_delete(stmt, arel, arel_attribute(primary_key)) else stmt.wheres = arel.constraints end affected = @klass.connection.delete(stmt, "#{@klass} Destroy") reset affected 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 @delegate_to_klass = false @to_sql = @arel = @loaded = @should_eager_load = 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? apply_join_dependency { |rel, _| relation = rel } end conn = klass.connection conn.unprepared_statement { conn.to_sql(relation.arel) } end end # Returns a hash of where conditions. # # User.where(name: 'Oscar').where_values_hash # # => {name: "Oscar"} def where_values_hash(relation_table_name = klass.table_name) where_clause.to_h(relation_table_name) end def scope_for_create(attributes = nil) scope = where_values_hash.merge!(create_with_value.stringify_keys) scope.merge!(attributes) if attributes scope 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 subject = loaded? ? records : self entries = subject.take([limit_value, 11].compact.min).map!(&:inspect) entries[10] = "..." if entries.size == 11 "#<#{self.class.name} [#{entries.join(', ')}]>" end def empty_scope? # :nodoc: @values == klass.unscoped.values end def has_limit_or_offset? # :nodoc: limit_value || offset_value end def alias_tracker(joins = [], aliases = nil) # :nodoc: joins += [aliases] if aliases ActiveRecord::Associations::AliasTracker.create(connection, table.name, joins) end def preload_associations(records) # :nodoc: preload = preload_values preload += includes_values unless eager_loading? preloader = nil preload.each do |associations| preloader ||= build_preloader preloader.preload records, associations end 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) skip_query_cache_if_necessary do @records = if eager_loading? apply_join_dependency do |relation, join_dependency| if ActiveRecord::NullRelation === relation [] else rows = connection.select_all(relation.arel, "SQL") join_dependency.instantiate(rows, &block) end.freeze end else klass.find_by_sql(arel, &block).freeze end preload_associations(@records) unless skip_preloading_value @records.each(&:readonly!) if readonly_value @loaded = true @records end end def skip_query_cache_if_necessary if skip_query_cache_value uncached do yield end else yield end 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