You need to specify the counter_cache option on the has_many side of the association when using a custom counter cache column. This is documented on the has_many association here: http://apidock.com/rails/ActiveRecord/Associations/ClassMethods/has_many [ci skip]

1 files changed, 7 insertions, 1 deletions

diff --git a/guides/source/association_basics.md b/guides/source/association_basics.md
index 3a2e522fa7..5c05f0c4b7 100644
--- a/guides/source/association_basics.md
+++ b/guides/source/association_basics.md
@@ -879,10 +879,12 @@ class Order < ActiveRecord::Base
   belongs_to :customer, counter_cache: :count_of_orders
 end
 class Customer < ActiveRecord::Base
-  has_many :orders
+  has_many :orders, counter_cache: :count_of_orders
 end
 ```
 
+NOTE: You only need to specify the :counter_cache option on the "has_many side" of the association when using a custom name for the counter cache.
+
 Counter cache columns are added to the containing model's list of read-only attributes through `attr_readonly`.
 
 ##### `:dependent`
@@ -1495,6 +1497,7 @@ The `has_many` association supports these options:
 * `:as`
 * `:autosave`
 * `:class_name`
+* `:counter_cache`
 * `:dependent`
 * `:foreign_key`
 * `:inverse_of`
@@ -1522,6 +1525,9 @@ class Customer < ActiveRecord::Base
 end
 ```
 
+##### `:counter_cache`
+This option can be used to configure a custom named `:counter_cache`. You only need this option when you customized the name of your `:counter_cache` on the [belongs_to association](#options-for-belongs-to).
+
 ##### `:dependent`
 
 Controls what happens to the associated objects when their owner is destroyed: