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 is a similar case to wanting ot use bind params for limit and
offset. Right now passing a range grows the amount of prepared
statements in an unbounded fashion. We could avoid using prepared
statements in that case, similar to what we do with arrays, but there's
a known number of variants for ranges.

This ends up duplicating some of the logic from Arel for how to handle
potentially infinite ranges, and that behavior may be removed from Arel
in the future.

Fixes #23074

Just noticed this on the [edge API].

[ci skip]

[edge API]: http://edgeapi.rubyonrails.org/classes/ActiveRecord/Transactions/ClassMethods.html

We want this method to be the single canonical source of information
about type metadata related to a model. This is the method I've been
continuously recommending people use if they need this sort of access,
as I have no plans to remove or change it at any point in the future.

We can do ourselves a favor and get people to use this instead of
relying on some other part of the internals that they shouldn't be by
making this method public.

Closes #21986.

This makes it possible to write custom types that define a different
mapping for STI columns.

It has been to use an overall rails command in ea4f0e2b, in order to unify.

Changed options for find_each and variants to have options start/finish instead of start_at/end_at based on comments
at https://github.com/rails/rails/pull/12257#issuecomment-74688344

- Before this patch if we try to find cache_key of a loaded but empty
  collection it used to give error because of trying to call `updated_at`
  on `nil` value generated by
  `collection.max_by(&timestamp_column).public_send(timestamp_column)`.
- This commit fixes above error by checking if size is greater than zero
  or not.

These methods are private and unused from anywhere.

Use `t.index` in `create_table` instead of `add_index`

It is slightly more efficient.

Revert "Use `key` as primary key in schema."

This reverts commit 350ae6cd.

`:primary_key` option does nothing if `id: false`.

https://github.com/rails/rails/blob/v5.0.0.beta1/activerecord/lib/active_record/connection_adapters/abstract/schema_statements.rb#L251-L261

😳

This reverts commit 11e85b91.

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.

The code that set the from clause was removed in
bdc51416. I did not give any reason for
doing so. My assumption was that I intended to change it to use the
clause objects, but forgot. We appeared to not have test coverage for
this case.

Fixes #22996

The code was changed to call `where` on a specific class in 813c8c07,
but no reasoning was given and I can't see any good reason why we would
need to do that. This will ensure that the method is called on whatever
class the scope is called on.

Fixes #23013

Arel handles substitution for bind parameters by now.

The default 'now'::date is CURRENT_DATE.

Example:

    create_table :posts do |t|
      t.datetime :published_at, default: -> { 'NOW()' }
    end

Closes #22584.

When you are using scopes and you chaining these scopes it is hard to
know which are the values that are incompatible. This way you can read
the message and know for which values you need to look for.

[Herminio Torres]

This reverts commit 5d41cb3b.

This implementation does not properly handle cases involving predicates
which are not associated with a bind param. I have the fix in mind, but
don't have time to implement just yet. It will be more similar to #22823
than not.

While the predicates are an arel equality node where the left side is a
full arel attribute, the binds just have the name of the column and
nothing else. This means that while splitting the predicates can include
the table as a factor, the binds cannot. It's entirely possible that we
might be able to have the bind params carry a bit more information (I
don't believe the name is used for anything but logging), and that is
probably a worthwhile change to make in the future.

However the simplest (and likely slightly faster) solution is to simply
use the indices of the conflicts in both cases. This means that we only
have to compute the collision space once, instead of twice even though
we're doing an additional array iteration. Regardless, this method isn't
a performance hotspot.

Close #22823.

[Ben Woosley & Sean Griffin]

Closes #23021.

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.

While the commit message (and changelog example) in
5e0b555b talked about sibling classes,
the added test had a child ignore its parent's scoping, which seems less
reasonable.

This PR addresses the issue described in https://github.com/rails/rails/pull/22967#issuecomment-170251635. If the database is non empty and has no new migrations than `db:migrate` will not set the environment. This PR works by always setting the environment value on successful `up` migration regardless of whether or not a migration was actually executed.

If for some reason some one is not able to set the environment from a migration this gives us an escape valve to manually set the environment for the database see https://github.com/rails/rails/pull/22967#issuecomment-170251635.

We will also fix the migration case, but this will ensure there is always a way to set the environment.

cc/ @sgrif

When running passing condition assertions in the same test the user had already
been saved at that point.

Split out so we have a not yet persisted user.

Rename condition tests to improve clarity a bit.