This behavior was broken by 36e9be85. When the value is assigned
directly, either through mass assignment or directly assigning a hash,
the hash gets passed through to this writer method directly. While this
is intended to handle certain cases, when an explicit converter has been
provided, we should continue to use that instead. The positioning of the
added guard caused the new behavior to override that case.

Fixes #25210

* Fix undefined method `owners' for NullPreloader:Class

Fixing undefined method `owners' for
ActiveRecord::Associations::Preloader::NullPreloader:Class

* Use Ruby 1.9 hash format

Use Ruby 1.9 hash format

#24192

[Rafael Mendonça França + Ladislav Smola]

```
$ ARCONN=mysql2 be ruby -w -Itest test/cases/scoping/default_scoping_test.rb
Using mysql2
/Users/kamipo/src/github.com/rails/rails/activerecord/lib/active_record/scoping/named.rb:158: warning: method redefined; discarding old female
/Users/kamipo/src/github.com/rails/rails/activerecord/lib/active_record/scoping/named.rb:158: warning: previous definition of female was here
/Users/kamipo/src/github.com/rails/rails/activerecord/lib/active_record/scoping/named.rb:158: warning: method redefined; discarding old male
/Users/kamipo/src/github.com/rails/rails/activerecord/lib/active_record/scoping/named.rb:158: warning: previous definition of male was here
```

Closes #23934.

This is a forward port of ac832a43

Previously the scope of all associations with extensions were wrapped in
an instance dependent proc. This made it impossible to preload such
associations.

I ran into an issue where validations on a suppressed record were
causing validation errors to be thrown on a record that was never going
to be saved.

There isn't a reason to run the validations on a record that doesn't
matter.

This change moves the suppressor up the chain to be run on the `save` or
`save!` in the validations rather than in persistence. The issue with
running it when we hit persistence is that the validations are run
first, then we hit persistance, and then we hit the suppressor. The
suppressor comes first.

The change to the test was required since I added the
`validates_presence_of` validations. Adding this alone was enough to
demonstrate the issue. I added a new test to demonstrate the new
behavior is explict.

This resolves a bug where if the primary key used is not `id` (ex:
`uuid`), and has a `validates_uniqueness_of` in the model, a uniqueness error
would be raised. This is a partial revert of commit `119b9181`, which introduced this behavior.

When passing in an array of different types of objects to `where`, it would only take into account the class of the first object in the array.

    PriceEstimate.where(estimate_of: [Treasure.find(1), Car.find(2)])
	# => SELECT "price_estimates".* FROM "price_estimates"
         WHERE ("price_estimates"."estimate_of_type" = 'Treasure' AND "price_estimates"."estimate_of_id" IN (1, 2))

This is fixed to properly look for any records matching both type and id:

    PriceEstimate.where(estimate_of: [Treasure.find(1), Car.find(2)])
    # => SELECT "price_estimates".* FROM "price_estimates"
         WHERE (("price_estimates"."estimate_of_type" = 'Treasure' AND "price_estimates"."estimate_of_id" = 1)
         OR ("price_estimates"."estimate_of_type" = 'Car' AND "price_estimates"."estimate_of_id" = 2))

Fixes #23209

This fixes incorrect assumptions made by e991c7b8 that we can assume the
DB is already casting the value for us. The enum type needs additional
information to perform casting, and needs a subtype.

I've opted not to call `super` in `cast`, as we have a known set of
types which we accept there, and the subtype likely doesn't accept them
(symbol -> integer doesn't make sense)

Close #23190

This reverts commit 224eddfc, reversing
changes made to 9d681fc7.

When merging the pull request, I misunderstood `has_secure_token` as declaring a model
has a token from birth and through the rest of its lifetime.

Therefore, supporting conditional creation doesn't make sense. You should never mark a
model as having a secure token if there's a time when it shouldn't have it on creation.

Given a default_scope on a parent of the current class, where that
parent is not the base class, the parent's STI condition would become
attached to the evaluated default scope, and then override the child's
own STI condition.

Instead, we can treat the STI condition as though it is a default scope,
and skip it in this situation: the scope will be merged into the base
relation, which already contains the correct STI condition.

Fixes #22426.

Pass through :if and :unless options from has_secure_token to the
generated before_create callback

When same association is loaded in the model creation callback
The new object is inserted into association twice

If argument of `build_record` has key and value which is same as
default value of database, we should also except the key from
`create_scope` in `initialize_attributes`.
Because at first `build_record` initialize record object with argument
of `build_record`, then assign attributes derived from Association's scope.
In this case `record.changed` does not include the key, which value is
same as default value of database, so we should add the key to except list.

Fix #21893.

Before this commit, if
`ActiveRecord::Base.belongs_to_required_by_default` is set to `true`,
then creating a record through `has_and_belongs_to_many` fails with the
cryptic error message `Left side must exist`. This is because
`inverse_of` isn't working properly in this case, presumably since we're
doing trickery with anonymous classes in the middle.

Rather than following this rabbit hole to try and get `inverse_of` to
work in a case that we know is not publicly supported, we can just turn
off this validation to match the behavior of 4.2 and earlier.

This reverts commit 60c97012, reversing
changes made to 6a25202d.

Reason: Broken build

This triggers the JoinDependency work to reflect on the associations
and trigger an error as follows:

  ActiveRecord::ConfigurationError: Association named 'account' was
  not found on Company; perhaps you misspelled it?

Fix Company.of_first_firm joins association name

Should be `Company.joins(:accounts)` not `Company.joins(:account)`.

Do the same for Client.of_first_firm

* When tried to use `Company#accounts` test/models/company.rb I got:

```
ActiveRecord::StatementInvalid: SQLite3::SQLException: no such column:
accounts.company_id: SELECT COUNT(*) AS count_all, "companies"."firm_id"
AS companies_firm_id FROM "companies" INNER JOIN "accounts" ON
"accounts"."company_id" = "companies"."id" GROUP BY "companies"."firm_id"
```

* The refactor on Calculations class was just to simplify the code

`inverse_of` on through associations was accidently removed/caused to
stop working in commit f8d2899d which was part of a refactoring on
`ThroughReflection`.

To fix we moved `inverse_of` and `check_validity_of_inverse!` to the
`AbstractReflection` so it's available to the `ThroughReflection`
without having to dup any methods. We then need to delegate `inverse_name`
method in `ThroughReflection`. `inverse_name` can't be moved to
`AbstractReflection` without moving methods that set the instance
variable `@automatic_inverse_of`.

This adds a test that ensures that `inverse_of` on a `ThroughReflection`
returns the correct class name, and the correct record for the inverse
relationship.

Fixes #21692

These new methods are used from the Active Record model layer to
determine which relations are viable to back a model. These new methods
allow us to change `conn.tables` in the future to only return tables and
no views. Same for `conn.table_exists?`.

The goal is to provide the following introspection methods on the
connection:

* `tables`
* `table_exists?`
* `views`
* `view_exists?`
* `data_sources` (views + tables)
* `data_source_exists?` (views + tables)

This reverts commit d5ba9a42, reversing
changes made to 30c50339.

Reason: This generate the dynalic finders more than one time

`lengh` should be `length`  

Since after 87d1aba3 `dependent: :destroy` callbacks on has_one
assocations run *after* destroy, it is possible that a nullification is
attempted on an already destroyed target:

    class Car < ActiveRecord::Base
      has_one :engine, dependent: :nullify
    end

    class Engine < ActiveRecord::Base
      belongs_to :car, dependent: :destroy
    end

    > car = Car.create!
    > engine = Engine.create!(car: car)
    > engine.destroy! # => ActiveRecord::ActiveRecordError: cannot update a
    >   destroyed record

In the above case, `engine.destroy!` deletes `engine` and *then* triggers the
deletion of `car`, which in turn triggers a nullification of `engine.car_id`.
However, `engine` is already destroyed at that point.

Fixes #21223.

If the through class has default scopes we should skip the statement
cache.

Closes #20745.

This makes it more clear that they are reserved keywords and also it
seems less redundant as the line already starts with the call to the
`enum` method.

As per the docs, `mark_for_destruction` should do nothing if `autosave`
is not set to true. We normally persist associations on a record no
matter what if the record is a new record, but we were always skipping
records which were `marked_for_destruction?`.

Fixes #20882

Also removes a false positive test that depends on the fixed bug:

At this time, counter_cache does not work with polymorphic relationships
(which is a bug). The test was added to make sure that no
StaleObjectError is raised when the car is destroyed. No such error is
currently raised because the lock version is not incremented by
appending a wheel to the car.

Furthermore, `assert_difference` succeeds because `car.wheels.count`
does not check the counter cache, but the collection size. The test will
fail if it is replaced with `car.wheels_count || 0`.

This code is so fucked. Things that cause this bug not to replicate:

- Defining the validation before the association (we end up calling
  `uniq!` on the errors in the autosave validation)
- Adding `accepts_nested_attributes_for` (I have no clue why. The only
  thing it does that should affect this is adds `autosave: true` to the
  inverse reflection, and doing that manually doesn't fix this).

This solution is a hack, and I'm almost certain there's a better way to
go about it, but this shouldn't cause a huge hit on validation times,
and is the simplest way to get it done.

Fixes #20874.

When preload is used in a default scope the preload_values were
returning nested arrays and causing the preloader to fail because it
doesn't know how to deal with nested arrays. So before calling preload!
we need to splat the arguments.

This is not needed to includes because it flatten its arguments.