Asssigning a parent id to a belongs_to association actually updates the object that is validated when the association has :validates => true

Previously we would just silently write the attribute. This can lead to
subtle bugs (for example, see the change in AutosaveAssociation where a
through association would wrongly gain an attribute.

Also, ensuring that we never gain any new attributes after
initialization will allow me to reduce our dependence on method_missing.

Don't construct association scope in initializer. This yields a big performance gain for cases where the association is never used to load the target, for example with preloading. Related: #1873.

Use proper objects to do the work to build the associations (adding methods, callbacks etc) rather than calling a whole bunch of methods with rather long names.

Split AssociationProxy into an Association class (and subclasses) which manages the association, and a CollectionProxy class which is *only* a proxy. Singular associations no longer have a proxy. See CHANGELOG for more.

This required changing the code to keep the association proxy for a belongs_to around, despite its target being nil. Which in turn required various changes to the way that stale target checking is handled, in order to support various edge cases (loaded target is nil then foreign key added, foreign key is changed and then changed back, etc). A side effect is that the code is nicer and more succinct.

Note that I am removing test_no_unexpected_aliasing since that is basically checking that the proxy for a belongs_to *does* change, which is the exact opposite of the intention of this commit. Also adding various tests for various edge cases and related things.

Phew, long commit message!

Rename AssociationReflection#primary_key_name to foreign_key, since the options key which it relates to is :foreign_key

Only call save on belongs_to associations if the record has changed or any nested associations have changed (resolves #3353)
Signed-off-by: NJosé Valim <jose.valim@gmail.com>

Only call save on belongs_to associations if the record has changed or any nested associations have changed (resolves #3353)
Signed-off-by: NJosé Valim <jose.valim@gmail.com>

- persisted? is the API defined in ActiveModel
- makes it easier for extension libraries to conform to ActiveModel APIs
  without concern for whether the extended object is specifically
  ActiveRecord

[#5927 state:committed]
Signed-off-by: NSantiago Pastorino <santiago@wyeworks.com>

Refactoring: replace the mix of variables like @finder_sql, @counter_sql, etc with just a single scope hash (created on initialization of the proxy). This is now used consistently across all associations. Therefore, all you have to do to ensure finding/counting etc is done correctly is implement the scope correctly.

This way parent models can get their own after_create and
after_update callbacks fired after has_one has done its job.

Refactoring: replace the mix of variables like @finder_sql, @counter_sql, etc with just a single scope hash (created on initialization of the proxy). This is now used consistently across all associations. Therefore, all you have to do to ensure finding/counting etc is done correctly is implement the scope correctly.

This will hopefully make Active Record run a bit more faster.

This will hopefully make Active Record run a bit more faster.

Signed-off-by: NJosé Valim <jose.valim@gmail.com>

Please check Lighthouse for more information.

This reverts commit 4a0d7c1a.

Signed-off-by: NJosé Valim <jose.valim@gmail.com>