Autoload ActiveModel::StrictValidationFailed

Currently, if environment doesn’t eager load code, invoking this
constant before calling #valid? on a model instance results in a
NameError.

[ci skip] Added examples for telephone_field_tag and url_field_tag methods

[ci skip] Added examples for search_field_tag method

[ci skip] Added examples for color_field_tag method

Reorder i18n guide

Currently, the section called "How to store your custom translations"
has several subheadings that make no sense, such as "Translations for
ActiveRecord models." These make more sense under the "Overview of the
I18n API Features" section. I moved the "How to store..." section down
to the more appropriate sub-headings "Using Different Backends" and
"Using Different Exception Handlers" and removed the "Customize your
i18n setup" header.

Changed the NullRelation so that when count is called with #group it wil...

* This is a follow up to: fe4b0eee
* The originating PR is #14222
* It should fix the build

additional note about routes in functional tests for engines [ci skip]

Changed the NullRelation so that when count is called with #group it will properly return an empty hash instead of zero. Fixes issue #14721

Conflicts:
	activerecord/CHANGELOG.md

Closes #14222.

This is a follow up to #6104

This does not have the backwards compatibility issues brought up in
implementation to break.

Avoid suggesting dangerous code in i18n guide

Calling `to_sym` on user input opens apps up to Denial of Service attacks, via the symbol table being expanded to consume vast swathes of memory.

It is a fairly common configuration to have DNS configured such that all subdomains route to your Rails app, in which case an attacker visits `www1.foo.com`, `www2.foo.com`, and so on until something gives.

It is far less likely to have this problem with TLDs, so that change was only for consistency.

Improve tests for duplicable, remove unnecessary constant

1. Improve tests
2. Remove unnecessary constant
3. Add docs for BigDecimal#duplicable?

Update AC::Metal documentation example

Include proper module since AV was extracted form AP as mentioned in #14659.

Refactor counter cache create and destroy

Changed change_column in PG schema_statements.rb to make sure that the u...

Changed change_column in PG schema_statements.rb to make sure that the uuid_generate function was not being quoted.

Display diagnostics in text format for xhr request

use YAML.load_file in database tasks example

Fix count on association relation (calls to empty and size).

rather than YAML.load(File.read(path)). YAML.load_file is also used in
guides/rails_guides/helper.rb since 2011, the only other precedent I could find.

[ci skip] Add missing end in one of the examples in Migrations.md.

Remove surplus period from assertion messages

Fix subscriptions not being unsubscribed.

968c581e have fixed the EagerLoadTest, but
not in the correct way.

The problem was when `empty?` or `size` was called on relation. It was
triggering `count(:all)`, which was passing `:all` as the column name to `count`
on Calculations.

On the other hand, the method `calculate` on Calculations was calling
`construct_relation_for_association_calculations` instead of `perform_calculation`,
because `has_include?` was returning `true` since `column_name` was present.

To prevent calling the wrong method to perform the calculation, we have to check
if the `column_name` is present and if it is different from `:all` (which is now used
to correctly do `count` with `select`).

More information here: https://github.com/rails/rails/commit/968c581ea34b5236af14805e6a77913b1cb36238#commitcomment-6006135

968c581e have introduced this bug #14744
on Association Relation when the method `empty?` or `size` was called.

Example:
  # Given an author that does have 3 posts, but none of them with the
  # title 'Some Title'
  Author.last.posts.where(title: 'Some Title').size
  # => 3

It was occurring, because the Association Relation had implemented these
methods based on `@association`, this way giving wrong results.

To fix it, was necessary to remove the methods `empty?` and `size` from
Association Relation. It just have to use these methods from Relation.

Example:
  # Given an author that does have 3 posts, but none of them with the
  # title 'Some Title'
  Author.last.posts.where(title: 'Some Title').size
  # => 0
  # Now it will return the correct value.

Fixes #14744.

Like rake tasks and runner blocks these blocks should also being shared
between applications since they are stored at the classes.

Fixes #14748