The current approach is broken because it uses a thread local value
which means on multi-threaded environments it has to be turned on
per thread. Secondly, ActiveSupport::Notifications does not
instrument items when there are not subscribers so this flag is
unnecessary.

These methods shouldn't be added to `SecureRandom`, as they are neither secure nor random. The more appropriate place for this seems to be `Digest`, so we should move them there. (Pull request welcomed!)

Marking this `:nodoc:` for now, so we don't accidentally ship it as public API.

See https://github.com/rails/rails/pull/15306/files#r13055862 for details.

Move writing unknown column exception to null attribute

Consolidate testing of update_all type casting

Making this change revealed several subtle bugs related to models with
no primary key, and anonymous classes. These have been fixed as well,
with regression tests added.

We have several test cases on "tricky" types that are essentially
testing that `update_all` goes through the same type casting behavior as
a normal assignment + save. We recently had another case to add this
test for another type in https://github.com/rails/rails/pull/12742.

Rather than testing this separately for every type which is "tricky"
when round tripping, let's instead have a fairly exhaustive test that
ensures we're getting the correct values at every step for `update_all`.
Given the structure of the code now, we can be confident that if the
type is correct, and `update_all` is type casting correctly, we're going
to get the right behavior for all types.

Deprecate automatic counter caches on has_many :through

Reliant on https://github.com/rails/rails/pull/15747 but pulled to a
separate PR to reduce noise. `has_many :through` associations have the
undocumented behavior of automatically detecting counter caches.
However, the way in which it does so is inconsistent with counter caches
everywhere else, and doesn't actually work consistently.

As with normal `has_many` associations, the user should specify the
counter cache on the `belongs_to`, if they'd like it updated.

`Attribute` should know about its name

This allows using polymorphism for the uninitialized attributes raising
an exception behavior.

Make the isolated tests run on JRuby

Allow proc and symbol as values for `only_integer` of `NumericalityValidator`

Closes #15919

This will make it less painful to add additional properties, which
should persist across writes, such as `name`.

Conflicts:
	activerecord/lib/active_record/attribute_set.rb

Move behavior of `read_attribute` to `AttributeSet`

Conflicts:
	activerecord/lib/active_record/attribute_set.rb
	activerecord/test/cases/attribute_set_test.rb

Encapsulate knowledge of type objects on `ActiveRecord::Result`

Move `attributes_before_type_cast` to `AttributeSet`

Conflicts:
	activerecord/lib/active_record/attribute_set.rb
	activerecord/test/cases/attribute_set_test.rb

Noticed that there was no section about Action View and added the heading.
Notable changes need to be compiled.

/cc @chancancode @zzak

[ci skip]

/cc @chancancode @zzak

Moved `Builder` to its own file, as it started looking very weird once I
added private methods to the `AttributeSet` class and the `Builder`
class started to grow.

Would like to refactor `fetch_value` to change to

```ruby
self[name].value(&block)
```

But that requires the attributes to know about their name, which they
currently do not.

This is a partial fix for #15853. It only works when a `preload`
is issued and not an `eager_load`. I've added a skipped failing
test-case to keep in mind that we need to deal with `eager_load`.

Fix a bug where NameError#name returns a qualified name in string

Replace x.sort_by!.select! with x.select!.sort_by!

Ruby's original behaviour is that :

  * It only returns a const name, not a qualified aname
  * It returns a symbol, not a string

Add a '--skip-routes' flag for the Controller generator.

This way it is possible to skip the addition of the 'get "foo/bar"' routes when
generating a controller.

Deal with regex match groups in excerpt

Original implementation has bugs if the regex contains a match group.

Example:

    excerpt('This is a beautiful? morning', /\b(beau\w*)\b/i, :radius => 5)
    Expected: "...is a beautiful? mor..."
    Actual: "...is a beautifulbeaut..."

The original phrase was being converted to a regex and returning the text
either side of the phrase as expected:

    'This is a beautiful? morning'.split(/beautiful/i, 2)
    # => ["This is a ", "? morning"]

When we have a match with groups the match is returned in the array.

Quoting the ruby docs: "If pattern is a Regexp, str is divided where the
pattern matches. [...] If pattern contains groups, the respective matches will
be returned in the array as well."

    'This is a beautiful? morning'.split(/\b(beau\w*)\b/iu, 2)
    # => ["This is a ", "beautiful", "? morning"]

If we assume we want to split on the first match – this fix makes that
assumption – we can pass the already assigned `phrase` variable as the place
to split (because we already know that a match exists from line 168).

Originally spotted by Louise Crow (@crowbot) at
https://github.com/mysociety/alaveteli/pull/1557

Improves readability of this line...

[ci skip]

Add warning section for `rescue_from Exception` in Guides

Always assume strings with non-numeric characters change numeric types

We previously only did this if the old value was zero, to make sure
numericality validations run and failed if the user gave 'wibble' as the
value, which would be type cast to 0. However, numericality validations
will fail if there are any non-numeric characters in the string, so 5 ->
'5wibble' should also be marked as changed.

Silence warning in test

We still had one file using `column_for_attribute` when it could return
nil, causing deprecation warnings in the tests.

Need to add individual `:nodoc:` for nested classes / modules to completely
remove the constants from the API.

Add #model_name instance method to ActiveModel::Naming