diff options
| -rw-r--r-- | activerecord/lib/active_record/associations.rb | 6 |
1 files changed, 4 insertions, 2 deletions
diff --git a/activerecord/lib/active_record/associations.rb b/activerecord/lib/active_record/associations.rb index cf3e63b4a3..b1951ce83f 100644 --- a/activerecord/lib/active_record/associations.rb +++ b/activerecord/lib/active_record/associations.rb @@ -149,7 +149,9 @@ module ActiveRecord class HasOneThroughNestedAssociationsAreReadonly < ThroughNestedAssociationsAreReadonly #:nodoc: end - class EagerLoadPolymorphicError < ActiveRecordError #:nodoc: + # This error is raised when trying to eager load a poloymorphic association using a JOIN. + # Eager loading polymorphic associations is only possible with ActiveRecord::QueryMethods#preload. + class EagerLoadPolymorphicError < ActiveRecordError def initialize(reflection = nil) if reflection super("Cannot eagerly load the polymorphic association #{reflection.name.inspect}") @@ -924,7 +926,7 @@ module ActiveRecord # For example if all the addressables are either of class Person or Company then a total # of 3 queries will be executed. The list of addressable types to load is determined on # the back of the addresses loaded. This is not supported if Active Record has to fallback - # to the previous implementation of eager loading and will raise <tt>ActiveRecord::EagerLoadPolymorphicError</tt>. + # to the previous implementation of eager loading and will raise ActiveRecord::EagerLoadPolymorphicError. # The reason is that the parent model's type is a column value so its corresponding table # name cannot be put in the +FROM+/+JOIN+ clauses of that query. # |