1 files changed, 193 insertions, 2 deletions

diff --git a/activerecord/CHANGELOG.md b/activerecord/CHANGELOG.md
index 22b1c8e95b..57d135d1aa 100644
--- a/activerecord/CHANGELOG.md
+++ b/activerecord/CHANGELOG.md
@@ -1,3 +1,194 @@
+*   Add `ActiveRecord::Base.suppress` to prevent the receiver from being saved
+    during the given block.
+
+    For example, here's a pattern of creating notifications when new comments
+    are posted. (The notification may in turn trigger an email, a push
+    notification, or just appear in the UI somewhere):
+
+        class Comment < ActiveRecord::Base
+          belongs_to :commentable, polymorphic: true
+          after_create -> { Notification.create! comment: self,
+            recipients: commentable.recipients }
+        end
+
+    That's what you want the bulk of the time. New comment creates a new
+    Notification. But there may well be off cases, like copying a commentable
+    and its comments, where you don't want that. So you'd have a concern
+    something like this:
+
+        module Copyable
+          def copy_to(destination)
+            Notification.suppress do
+              # Copy logic that creates new comments that we do not want triggering
+              # notifications.
+            end
+          end
+        end
+
+    *Michael Ryan*
+
+*   `:time` option added for `#touch`
+    Fixes #18905.
+
+    *Hyonjee Joo*
+
+*   Deprecated passing of `start` value to `find_in_batches` and `find_each`
+    in favour of `begin_at` value.
+
+    *Vipul A M*
+
+*   Add `foreign_key_exists?` method.
+
+    *Tõnis Simo*
+
+*   Use SQL COUNT and LIMIT 1 queries for `none?` and `one?` methods if no block or limit is given,
+    instead of loading the entire collection to memory.
+    This applies to relations (e.g. `User.all`) as well as associations (e.g. `account.users`)
+
+        # Before:
+
+        users.none?
+        # SELECT "users".* FROM "users"
+
+        users.one?
+        # SELECT "users".* FROM "users"
+
+        # After:
+
+        users.none?
+        # SELECT 1 AS one FROM "users" LIMIT 1
+
+        users.one?
+        # SELECT COUNT(*) FROM "users"
+
+    *Eugene Gilburg*
+
+*   Have `enum` perform type casting consistently with the rest of Active
+    Record, such as `where`.
+
+    *Sean Griffin*
+
+*   `scoping` no longer pollutes the current scope of sibling classes when using
+    STI. e.x.
+
+    StiOne.none.scoping do
+      StiTwo.all
+    end
+
+    Fixes #18806.
+
+    *Sean Griffin*
+
+*   `remove_reference` with `foreign_key: true` removes the foreign key before
+    removing the column. This fixes a bug where it was not possible to remove
+    the column on MySQL.
+
+    Fixes #18664.
+
+    *Yves Senn*
+
+*   `find_in_batches` now accepts an `:end_at` parameter that complements the `:start`
+     parameter to specify where to stop batch processing.
+
+    *Vipul A M*
+
+*   Fix rounding problem for PostgreSQL timestamp column.
+
+    If timestamp column have the precision, it need to format according to
+    the precision of timestamp column.
+
+    *Ryuta Kamizono*
+
+*   Respect the database default charset for `schema_migrations` table.
+
+    The charset of `version` column in `schema_migrations` table is depend
+    on the database default charset and collation rather than the encoding
+    of the connection.
+
+    *Ryuta Kamizono*
+
+*   Raise `ArgumentError` when passing `nil` or `false` to `Relation#merge`.
+
+    These are not valid values to merge in a relation so it should warn the users
+    early.
+
+    *Rafael Mendonça França*
+
+*   Use `SCHEMA` instead of `DB_STRUCTURE` for specifying structure file.
+
+    This makes the db:structure tasks consistent with test:load_structure.
+
+    *Dieter Komendera*
+
+*   Respect custom primary keys for associations when calling `Relation#where`
+
+    Fixes #18813.
+
+    *Sean Griffin*
+
+*   Fixed several edge cases which could result in a counter cache updating
+    twice or not updating at all for `has_many` and `has_many :through`.
+
+    Fixes #10865.
+
+    *Sean Griffin*
+
+*   Foreign keys added by migrations were given random, generated names. This
+    meant a different `structure.sql` would be generated every time a developer
+    ran migrations on their machine.
+
+    The generated part of foreign key names is now a hash of the table name and
+    column name, which is consistent every time you run the migration.
+
+    *Chris Sinjakli*
+
+*   Validation errors would be raised for parent records when an association
+    was saved when the parent had `validate: false`. It should not be the
+    responsibility of the model to validate an associated object unless the
+    object was created or modified by the parent.
+
+    This fixes the issue by skipping validations if the parent record is
+    persisted, not changed, and not marked for destruction.
+
+    Fixes #17621.
+
+    *Eileen M. Uchitelle, Aaron Patterson*
+
+*   Fix n+1 query problem when eager loading nil associations (fixes #18312)
+
+    *Sammy Larbi*
+
+*   Change the default error message from `can't be blank` to `must exist` for
+    the presence validator of the `:required` option on `belongs_to`/`has_one` associations.
+
+    *Henrik Nygren*
+
+*   Fixed ActiveRecord::Relation#group method when argument is SQL reserved key word:
+
+    Example:
+
+        SplitTest.group(:key).count
+        Property.group(:value).count
+
+    *Bogdan Gusiev*
+
+*   Added the `#or` method on ActiveRecord::Relation, allowing use of the OR
+    operator to combine WHERE or HAVING clauses.
+
+    Example:
+
+        Post.where('id = 1').or(Post.where('id = 2'))
+        # => SELECT * FROM posts WHERE (id = 1) OR (id = 2)
+
+    *Sean Griffin*, *Matthew Draper*, *Gael Muller*, *Olivier El Mekki*
+
+*   Don't define autosave association callbacks twice from
+    `accepts_nested_attributes_for`.
+
+    Fixes #18704.
+
+    *Sean Griffin*
+
 *   Integer types will no longer raise a `RangeError` when assigning an
     attribute, but will instead raise when going to the database.
 
@@ -7,7 +198,7 @@
     *Sean Griffin*
 
 *   Values which would error while being sent to the database (such as an
-    ASCII-8BIT string with invalid UTF-8 bytes on Sqlite3), no longer error on
+    ASCII-8BIT string with invalid UTF-8 bytes on SQLite3), no longer error on
     assignment. They will still error when sent to the database, but you are
     given the ability to re-assign it to a valid value.
 
@@ -62,7 +253,7 @@
     A deprecation warning will be emitted if you have a `:time` column, and have
     not explicitly opted out.
 
-    Fixes #3145
+    Fixes #3145.
 
     *Sean Griffin*