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-rw-r--r--guides/source/association_basics.md64
1 files changed, 41 insertions, 23 deletions
diff --git a/guides/source/association_basics.md b/guides/source/association_basics.md
index 03d3daecc8..6e68935f9b 100644
--- a/guides/source/association_basics.md
+++ b/guides/source/association_basics.md
@@ -709,55 +709,73 @@ class Book < ApplicationRecord
end
```
-By default, Active Record doesn't know about the connection between these associations. This can lead to two copies of an object getting out of sync:
+Active Record will attempt to automatically identify that these two models share a bi-directional association based on the association name. In this way, Active Record will only load one copy of the `Author` object, making your application more efficient and preventing inconsistent data:
```ruby
a = Author.first
b = a.books.first
a.first_name == b.author.first_name # => true
-a.first_name = 'Manny'
-a.first_name == b.author.first_name # => false
+a.first_name = 'David'
+a.first_name == b.author.first_name # => true
```
-This happens because `a` and `b.author` are two different in-memory representations of the same data, and neither one is automatically refreshed from changes to the other. Active Record provides the `:inverse_of` option so that you can inform it of these relations:
+Active Record supports automatic identification for most associations with standard names. However, Active Record will not automatically identify bi-directional associations that contain any of the following options:
+
+* `:conditions`
+* `:through`
+* `:polymorphic`
+* `:class_name`
+* `:foreign_key`
+
+For example, consider the following model declarations:
```ruby
class Author < ApplicationRecord
- has_many :books, inverse_of: :author
+ has_many :books
end
class Book < ApplicationRecord
- belongs_to :author, inverse_of: :books
+ belongs_to :writer, class_name: 'Author', foreign_key: 'author_id'
end
```
-With these changes, Active Record will only load one copy of the author object, preventing inconsistencies and making your application more efficient:
+Active Record will no longer automatically recognize the bi-directional association:
```ruby
a = Author.first
b = a.books.first
-a.first_name == b.author.first_name # => true
-a.first_name = 'Manny'
-a.first_name == b.author.first_name # => true
+a.first_name == b.writer.first_name # => true
+a.first_name = 'David'
+a.first_name == b.writer.first_name # => false
+```
+
+Active Record provides the `:inverse_of` option so you can explicitly declare bi-directional associations:
+
+```ruby
+class Author < ApplicationRecord
+ has_many :books, inverse_of: 'writer'
+end
+
+class Book < ApplicationRecord
+ belongs_to :writer, class_name: 'Author', foreign_key: 'author_id'
+end
```
-There are a few limitations to `inverse_of` support:
+By including the `:inverse_of` option in the `has_many` association declaration, Active Record will now recognize the bi-directional association:
+
+```ruby
+a = Author.first
+b = a.books.first
+a.first_name == b.writer.first_name # => true
+a.first_name = 'David'
+a.first_name == b.writer.first_name # => true
+```
+
+There are a few limitations to `:inverse_of` support:
* They do not work with `:through` associations.
* They do not work with `:polymorphic` associations.
* They do not work with `:as` associations.
-* For `belongs_to` associations, `has_many` inverse associations are ignored.
-
-Every association will attempt to automatically find the inverse association
-and set the `:inverse_of` option heuristically (based on the association name).
-Most associations with standard names will be supported. However, associations
-that contain the following options will not have their inverses set
-automatically:
-
-* `:conditions`
-* `:through`
-* `:polymorphic`
-* `:foreign_key`
Detailed Association Reference
------------------------------