diff options
Diffstat (limited to 'activerecord/lib/active_record/associations/preloader.rb')
| -rw-r--r-- | activerecord/lib/active_record/associations/preloader.rb | 25 |
1 files changed, 17 insertions, 8 deletions
diff --git a/activerecord/lib/active_record/associations/preloader.rb b/activerecord/lib/active_record/associations/preloader.rb index 97f4bd3811..ecf6fb8643 100644 --- a/activerecord/lib/active_record/associations/preloader.rb +++ b/activerecord/lib/active_record/associations/preloader.rb @@ -10,13 +10,13 @@ module ActiveRecord # end # # class Book < ActiveRecord::Base - # # columns: title, sales + # # columns: title, sales, author_id # end # # When you load an author with all associated books Active Record will make # multiple queries like this: # - # Author.includes(:books).where(:name => ['bell hooks', 'Homer').to_a + # Author.includes(:books).where(name: ['bell hooks', 'Homer']).to_a # # => SELECT `authors`.* FROM `authors` WHERE `name` IN ('bell hooks', 'Homer') # => SELECT `books`.* FROM `books` WHERE `author_id` IN (2, 5) @@ -54,6 +54,8 @@ module ActiveRecord autoload :BelongsTo, 'active_record/associations/preloader/belongs_to' end + NULL_RELATION = Struct.new(:values, :where_clause, :joins_values).new({}, Relation::WhereClause.empty, []) + # Eager loads the named associations for the given Active Record record(s). # # In this description, 'association name' shall refer to the name passed @@ -88,9 +90,6 @@ module ActiveRecord # [ :books, :author ] # { author: :avatar } # [ :books, { author: :avatar } ] - - NULL_RELATION = Struct.new(:values, :where_clause, :joins_values).new({}, Relation::WhereClause.empty, []) - def preload(records, associations, preload_scope = nil) records = Array.wrap(records).compact.uniq associations = Array.wrap(associations) @@ -107,6 +106,7 @@ module ActiveRecord private + # Loads all the given data into +records+ for the +association+. def preloaders_on(association, records, scope) case association when Hash @@ -116,7 +116,7 @@ module ActiveRecord when String preloaders_for_one(association.to_sym, records, scope) else - raise ArgumentError, "#{association.inspect} was not recognised for preload" + raise ArgumentError, "#{association.inspect} was not recognized for preload" end end @@ -132,6 +132,11 @@ module ActiveRecord } end + # Loads all the given data into +records+ for a singular +association+. + # + # Functions by instantiating a preloader class such as Preloader::HasManyThrough and + # call the +run+ method for each passed in class in the +records+ argument. + # # Not all records have the same class, so group then preload group on the reflection # itself so that if various subclass share the same association then we do not split # them unnecessarily @@ -160,7 +165,7 @@ module ActiveRecord h end - class AlreadyLoaded + class AlreadyLoaded # :nodoc: attr_reader :owners, :reflection def initialize(klass, owners, reflection, preload_scope) @@ -175,12 +180,16 @@ module ActiveRecord end end - class NullPreloader + class NullPreloader # :nodoc: def self.new(klass, owners, reflection, preload_scope); self; end def self.run(preloader); end def self.preloaded_records; []; end end + # Returns a class containing the logic needed to load preload the data + # and attach it to a relation. For example +Preloader::Association+ or + # +Preloader::HasManyThrough+. The class returned implements a `run` method + # that accepts a preloader. def preloader_for(reflection, owners, rhs_klass) return NullPreloader unless rhs_klass |