Module: Sequel::Plugins::AutoRestrictEagerGraph

Defined in:

lib/sequel/plugins/auto_restrict_eager_graph.rb

Overview

The auto_restrict_eager_graph plugin will automatically disallow the use of eager_graph for associations that have associated blocks but no :graph_* association options. The reason for this is the block will have an effect during regular and eager loading, but not loading via eager_graph, and it is likely that whatever the block is doing should have an equivalent done when eager_graphing. Most likely, not including a :graph_* option was either an oversight (and one should be added), or use with eager_graph was never intended (and usage should be forbidden). Disallowing eager_graph in this case prevents likely unexpected behavior during eager_graph.

As an example of this, consider the following code:

Album.one_to_many :popular_tracks, class: :Track do |ds|
  ds = ds.where(popular: true)
end  

Album.eager(:popular_tracks).all
# SELECT * FROM albums
# SELECT * FROM tracks WHERE ((popular IS TRUE) AND (album_id IN (...)))

# Notice that no condition for tracks.popular is added.
Album.eager_graph(:popular_tracks).all
# SELECT ... FROM albums LEFT JOIN tracks ON (tracks.album_id = albums.id)

With the auto_restrict_eager_graph plugin, the eager_graph call above will raise an error, alerting you to the fact that you either should not be using eager_graph with the association, or that you should be adding an appropriate :graph_* option, such as:

Album.one_to_many :popular_tracks, class: :Track, graph_conditions: {popular: true} do |ds|
  ds = ds.where(popular: true)
end

Usage:

# Automatically restrict eager_graph for associations if appropriate for all
# model subclasses (called before loading subclasses)
Sequel::Model.plugin :auto_restrict_eager_graph

# Automatically restrict eager_graph for associations in Album class
Album.plugin :auto_restrict_eager_graph

Defined Under Namespace

Modules: ClassMethods