1 files changed, 261 insertions, 5 deletions
diff --git a/activerecord/CHANGELOG.md b/activerecord/CHANGELOG.md
index d289f616b8..f1f9cf1ffd 100644
--- a/activerecord/CHANGELOG.md
+++ b/activerecord/CHANGELOG.md
@@ -1,8 +1,264 @@
+*   Properly detect if a connection is still active before using it
+    in multi-threaded environments.
+
+    Fixes #12867.
+
+    *Kevin Casey*, *Matthew Draper*, *William (B.J.) Snow Orvis*
+
+*   When inverting add_index use the index name if present instead of
+    the columns.
+
+    If there are two indices with matching columns and one of them is
+    explicitly named then reverting the migration adding the named one
+    would instead drop the unnamed one.
+
+    The inversion of add_index will now drop the index by its name if
+    it is present.
+
+    *Hubert Dąbrowski*
+
+*   Add flag to disable schema dump after migration.
+
+    Add a config parameter on Active Record named `dump_schema_after_migration`
+    which is true by default. Now schema dump does not happen at the
+    end of migration rake task if `dump_schema_after_migration` is false.
+
+    *Emil Soman*
+
+*   `find_in_batches`, `find_each`, `Result#each` and `Enumerable#index_by` now
+    return an `Enumerator` that can calculate its size.
+
+    See also #13938.
+
+    *Marc-André Lafortune*
+
+*   Make sure transaction state gets reset after a commit operation on the record.
+
+    If a new transaction was open inside a callback, the record was loosing track
+    of the transaction level state, and it was leaking that state.
+
+    Fixes #12566.
+
+    *arthurnn*
+
+*   Pass `has_and_belongs_to_many` `:autosave` option to
+    the underlying `has_many :through` association.
+
+    Fixes #13923.
+
+    *Yves Senn*
+
+*   PostgreSQL implementation of `SchemaStatements#index_name_exists?`.
+
+    The database agnostic implementation does not detect with indexes that are
+    not supported by the ActiveRecord schema dumper. For example, expressions
+    indexes would not be detected.
+
+    Fixes #11018.
+
+    *Jonathan Baudanza*
+
+*   Parsing PostgreSQL arrays with empty strings now works correctly.
+
+    Previously, if you tried to parse `{"1","","2","","3"}` the result
+    would be `["1","2","3"]`, removing the empty strings from the array,
+    which would be incorrect. Now it will correctly produce `["1","","2","","3"]`
+    as the result of parsing the above PostgreSQL array.
+
+    Fixes #13907.
+
+    *Maurício Linhares*
+
+*   Associations now raise `ArgumentError` on name conflicts.
+
+    Dangerous association names conflicts include instance or class methods already
+    defined by `ActiveRecord::Base`.
+
+    Example:
+
+        class Car < ActiveRecord::Base
+          has_many :errors
+        end
+        # Will raise ArgumentError.
+
+    Fixes #13217.
+
+    *Lauro Caetano*
+
+*   Fix regressions on `select_*` methods.
+    When `select_*` methods receive a `Relation` object, they should be able to
+    get the arel/binds from it.
+    Also fix regressions on `select_rows` that was ignoring the binds.
+
+    Fixes #7538, #12017, #13731, #12056.
+
+    *arthurnn*
+
+*   Active Record objects can now be correctly dumped, loaded and dumped again
+    without issues.
+
+    Previously, if you did `YAML.dump`, `YAML.load` and then `YAML.dump` again
+    in an Active Record model that used serialization it would fail at the last
+    dump due to the fields not being correctly serialized before being dumped
+    to YAML. Now it is possible to dump and load the same object as many times
+    as needed without any issues.
+
+    Fixes #13861.
+
+    *Maurício Linhares*
+
+*   `find_in_batches` now returns an `Enumerator` when called without a block, so that it
+    can be chained with other `Enumerable` methods.
+
+    *Marc-André Lafortune*
+
+*   `enum` now raises on "dangerous" name conflicts.
+
+    Dangerous name conflicts includes instance or class method conflicts
+    with methods defined within `ActiveRecord::Base` but not its ancestors,
+    as well as conflicts with methods generated by other enums on the same
+    class.
+
+    Fixes #13389.
+
+    *Godfrey Chan*
+
+*   `scope` now raises on "dangerous" name conflicts.
+
+    Similar to dangerous attribute methods, a scope name conflict is
+    dangerous if it conflicts with an existing class method defined within
+    `ActiveRecord::Base` but not its ancestors.
+
+    See also #13389.
+
+    *Godfrey Chan*, *Philippe Creux*
+
+*   Correctly send an user provided statement to a `lock!()` call.
+
+        person.lock! 'FOR SHARE NOWAIT'
+        # Before: SELECT * ... LIMIT 1 FOR UPDATE
+        # After: SELECT * ... LIMIT 1 FOR SHARE NOWAIT
+
+    Fixes #13788.
+
+    *Maurício Linhares*
+
+*   Handle aliased attributes `select()`, `order()` and `reorder()`.
+
+    *Tsutomu Kuroda*
+
+*   Reset the collection association when calling `reset` on it.
+
+    Before:
+
+        post.comments.loaded? # => true
+        post.comments.reset
+        post.comments.loaded? # => true
+
+    After:
+
+        post.comments.loaded? # => true
+        post.comments.reset
+        post.comments.loaded? # => false
+
+    Fixes #13777.
+
+    *Kelsey Schlarman*
+
+*   Make enum fields work as expected with the `ActiveModel::Dirty` API.
+
+    Before this change, using the dirty API would have surprising results:
+
+        conversation = Conversation.new
+        conversation.status = :active
+        conversation.status = :archived
+        conversation.status_was # => 0
+
+    After this change, the same code would result in:
+
+        conversation = Conversation.new
+        conversation.status = :active
+        conversation.status = :archived
+        conversation.status_was # => "active"
+
+    *Rafael Mendonça França*
+
+*   `has_one` and `belongs_to` accessors don't add ORDER BY to the queries
+    anymore.
+
+    Since Rails 4.0, we add an ORDER BY in the `first` method to ensure
+    consistent results among different database engines. But for singular
+    associations this behavior is not needed since we will have one record to
+    return. As this ORDER BY option can lead some performance issues we are
+    removing it for singular associations accessors.
+
+    Fixes #12623.
+
+    *Rafael Mendonça França*
+
+*   Prepend table name for column names passed to `Relation#select`.
+
+    Example:
+
+        Post.select(:id)
+        # Before: => SELECT id FROM "posts"
+        # After: => SELECT "posts"."id" FROM "posts"
+
+    *Yves Senn*
+
+*   Fail early with "Primary key not included in the custom select clause"
+    in `find_in_batches`.
+
+    Before this patch, the exception was raised after the first batch was
+    yielded to the block. This means that you only get it, when you hit the
+    `batch_size` treshold. This could shadow the issue in development.
+
+    *Alexander Balashov*
+
+*   Ensure `second` through `fifth` methods act like the `first` finder.
+
+    The famous ordinal Array instance methods defined in ActiveSupport
+    (`first`, `second`, `third`, `fourth`, and `fifth`) are now available as
+    full-fledged finders in ActiveRecord. The biggest benefit of this is ordering
+    of the records returned now defaults to the table's primary key in ascending order.
+
+    Fixes #13743.
+
+    Example:
+
+        User.all.second
+
+        # Before
+        # => 'SELECT  "users".* FROM "users"'
+
+        # After
+        # => SELECT  "users".* FROM "users"   ORDER BY "users"."id" ASC LIMIT 1 OFFSET 1'
+
+        User.offset(3).second
+
+        # Before
+        # => 'SELECT "users".* FROM "users"  LIMIT -1 OFFSET 3' # sqlite3 gem
+        # => 'SELECT "users".* FROM "users"  OFFSET 3' # pg gem
+        # => 'SELECT `users`.* FROM `users`  LIMIT 18446744073709551615 OFFSET 3' # mysql2 gem
+
+        # After
+        # => SELECT  "users".* FROM "users"   ORDER BY "users"."id" ASC LIMIT 1 OFFSET 4'
+
+    *Jason Meller*
+
+*   ActiveRecord states are now correctly restored after a rollback for
+    models that did not define any transactional callbacks (i.e.
+    `after_commit`, `after_rollback` or `after_create`).
+
+    Fixes #13744.
+
+    *Godfrey Chan*
+
 *   Make `touch` fire the `after_commit` and `after_rollback` callbacks.
 
     *Harry Brundage*
 
-*   Enable partial indexes for sqlite >= 3.8.0
+*   Enable partial indexes for `sqlite >= 3.8.0`.
 
     See http://www.sqlite.org/partialindex.html
 
@@ -130,7 +386,7 @@
     This ensures that `change_table` and `create_table` will use
     similar objects.
 
-    Fixes #13577 and #13503.
+    Fixes #13577, #13503.
 
     *Nishant Modak*, *Prathamesh Sonpatki*, *Rafael Mendonça França*
 
@@ -675,7 +931,7 @@
 
     *Severin Schoepke*
 
-*   `ActiveRecord::Store` works together with PG `hstore` columns.
+*   `ActiveRecord::Store` works together with PostgreSQL `hstore` columns.
 
     Fixes #12452.
 
@@ -961,7 +1217,7 @@
 
     *Yves Senn* , *Severin Schoepke*
 
-*   Fix multidimensional PG arrays containing non-string items.
+*   Fix multidimensional PostgreSQL arrays containing non-string items.
 
     *Yves Senn*
 
@@ -979,7 +1235,7 @@
 
     *Richard Schneeman*
 
-*   Removed redundant override of `xml` column definition for PG,
+*   Removed redundant override of `xml` column definition for PostgreSQL,
     in order to use `xml` column type instead of `text`.
 
     *Paul Nikitochkin*, *Michael Nikitochkin*