v4.0.2 - Show latest stable - 0 notes - Class: Preloader
new(records, associations, preload_scope = nil) public

Eager loads the named associations for the given Active Record record(s).

In this description, ‘association name’ shall refer to the name passed to an association creation method. For example, a model that specifies belongs_to :author, has_many :buyers has association names :author and :buyers.


records is an array of ActiveRecord::Base. This array needs not be flat, i.e. records itself may also contain arrays of records. In any case, preload_associations will preload the all associations records by flattening records.

associations specifies one or more associations that you want to preload. It may be:

  • a Symbol or a String which specifies a single association name. For example, specifying :books allows this method to preload all books for an Author.

  • an Array which specifies multiple association names. This array is processed recursively. For example, specifying [:avatar, :books] allows this method to preload an author’s avatar as well as all of his books.

  • a Hash which specifies multiple association names, as well as association names for the to-be-preloaded association objects. For example, specifying { author: :avatar } will preload a book’s author, as well as that author’s avatar.

:associations has the same format as the :include option for ActiveRecord::Base.find. So associations could look like this:

[ :books, :author ]
{ author: :avatar }
[ :books, { author: :avatar } ]
Show source
Register or log in to add new notes.