rails--rails/activerecord/CHANGELOG.md

• 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

• Allow :precision option for time type columns.

  Ryuta Kamizono

• 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.

  Fixes several vague issues which were never reported directly. See the commit message from the commit which added this line for some examples.

  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 assignment. They will still error when sent to the database, but you are given the ability to re-assign it to a valid value.

  Fixes #18580.

  Sean Griffin

• Don't remove join dependencies in Relation#exists?

  Fixes #18632.

  Sean Griffin

• Invalid values assigned to a JSON column are assumed to be nil.

  Fixes #18629.

  Sean Griffin

• Add ActiveRecord::Base#accessed_fields, which can be used to quickly discover which fields were read from a model when you are looking to only select the data you need from the database.

  Sean Griffin

• Introduce the :if_exists option for drop_table.

  Example:

  drop_table(:posts, if_exists: true)
  

  That would execute:

  DROP TABLE IF EXISTS posts
  

  If the table doesn't exist, if_exists: false (the default) raises an exception whereas if_exists: true does nothing.

  Cody Cutrer, Stefan Kanev, Ryuta Kamizono

• Don't run SQL if attribute value is not changed for update_attribute method.

  Prathamesh Sonpatki

• time columns can now get affected by time_zone_aware_attributes. If you have set config.time_zone to a value other than 'UTC', they will be treated as in that time zone by default in Rails 5.1. If this is not the desired behavior, you can set

  ActiveRecord::Base.time_zone_aware_types = [:datetime]
  

  A deprecation warning will be emitted if you have a :time column, and have not explicitly opted out.

  Fixes #3145.

  Sean Griffin

• Tests now run after_commit callbacks. You no longer have to declare uses_transaction ‘test name’ to test the results of an after_commit.

  after_commit callbacks run after committing a transaction whose parent is not joinable?: un-nested transactions, transactions within test cases, and transactions in console --sandbox.

  arthurnn, Ravil Bayramgalin, Matthew Draper

• nil as a value for a binary column in a query no longer logs as "", and instead logs as just "nil".

  Sean Griffin

• attribute_will_change! will no longer cause non-persistable attributes to be sent to the database.

  Fixes #18407.

  Sean Griffin

• Remove support for the protected_attributes gem.

  Carlos Antonio da Silva, Roberto Miranda

• Fix accessing of fixtures having non-string labels like Fixnum.

  Prathamesh Sonpatki

• Remove deprecated support to preload instance-dependent associations.

  Yves Senn

• Remove deprecated support for PostgreSQL ranges with exclusive lower bounds.

  Yves Senn

• Remove deprecation when modifying a relation with cached arel. This raises an ImmutableRelation error instead.

  Yves Senn

• Added ActiveRecord::SecureToken in order to encapsulate generation of unique tokens for attributes in a model using SecureRandom.

  Roberto Miranda

• Change the behavior of boolean columns to be closer to Ruby's semantics.

  Before this change we had a small set of "truthy", and all others are "falsy".

  Now, we have a small set of "falsy" values and all others are "truthy" matching Ruby's semantics.

  Rafael Mendonça França

• Deprecate ActiveRecord::Base.errors_in_transactional_callbacks=.

  Rafael Mendonça França

• Change transaction callbacks to not swallow errors.

  Before this change any errors raised inside a transaction callback were getting rescued and printed in the logs.

  Now these errors are not rescued anymore and just bubble up, as the other callbacks.

  Rafael Mendonça França

• Remove deprecated sanitize_sql_hash_for_conditions.

  Rafael Mendonça França

• Remove deprecated Reflection#source_macro.

  Rafael Mendonça França

• Remove deprecated symbolized_base_class and symbolized_sti_name.

  Rafael Mendonça França

• Remove deprecated ActiveRecord::Base.disable_implicit_join_references=.

  Rafael Mendonça França

• Remove deprecated access to connection specification using a string accessor.

  Now all strings will be handled as a URL.

  Rafael Mendonça França

• Change the default null value for timestamps to false.

  Rafael Mendonça França

• Return an array of pools from connection_pools.

  Rafael Mendonça França

• Return a null column from column_for_attribute when no column exists.

  Rafael Mendonça França

• Remove deprecated serialized_attributes.

  Rafael Mendonça França

• Remove deprecated automatic counter caches on has_many :through.

  Rafael Mendonça França

• Change the way in which callback chains can be halted.

  The preferred method to halt a callback chain from now on is to explicitly throw(:abort). In the past, returning false in an ActiveRecord before_ callback had the side effect of halting the callback chain. This is not recommended anymore and, depending on the value of the config.active_support.halt_callback_chains_on_return_false option, will either not work at all or display a deprecation warning.

  claudiob

• Clear query cache on rollback.

  Florian Weingarten

• Fixed setting of foreign_key for through associations while building of new record.

  Fixes #12698.

  Ivan Antropov

• Improve a dump of the primary key support. If it is not a default primary key, correctly dump the type and options.

  Fixes #14169, #16599.

  Ryuta Kamizono

• Format the datetime string according to the precision of the datetime field.

  Incompatible to rounding behavior between MySQL 5.6 and earlier.

  In 5.5, when you insert 2014-08-17 12:30:00.999999 the fractional part is ignored. In 5.6, it's rounded to 2014-08-17 12:30:01:

  http://bugs.mysql.com/bug.php?id=68760

  Ryuta Kamizono

• Allow precision option for MySQL datetimes.

  Ryuta Kamizono

• Fixed automatic inverse_of for models nested in module.

  Andrew McCloud

• Change ActiveRecord::Relation#update behavior so that it can be called without passing ids of the records to be updated.

  This change allows to update multiple records returned by ActiveRecord::Relation with callbacks and validations.

  # Before
  # ArgumentError: wrong number of arguments (1 for 2)
  Comment.where(group: 'expert').update(body: "Group of Rails Experts")
  
  # After
  # Comments with group expert updated with body "Group of Rails Experts"
  Comment.where(group: 'expert').update(body: "Group of Rails Experts")
  

  Prathamesh Sonpatki

• Fix reaping_frequency option when the value is a string.

  This usually happens when it is configured using DATABASE_URL.

  korbin

• Fix error message when trying to create an associated record and the foreign key is missing.

  Before this fix the following exception was being raised:

  NoMethodError: undefined method `val' for #<Arel::Nodes::BindParam:0x007fc64d19c218>
  

  Now the message is:

  ActiveRecord::UnknownAttributeError: unknown attribute 'foreign_key' for Model.
  

  Rafael Mendonça França

• When a table has a composite primary key, the primary_key method for SQLite3 and PostgreSQL adapters was only returning the first field of the key. Ensures that it will return nil instead, as Active Record doesn't support composite primary keys.

  Fixes #18070.

  arthurnn

• validates_size_of / validates_length_of do not count records, which are marked_for_destruction?.

  Fixes #7247.

  Yves Senn

• Ensure first! and friends work on loaded associations.

  Fixes #18237.

  Sean Griffin

• eager_load preserves readonly flag for associations.

  Closes #15853.

  Takashi Kokubun

• Provide :touch option to save() to accommodate saving without updating timestamps.

  Fixes #18202.

  Dan Olson

• Provide a more helpful error message when an unsupported class is passed to serialize.

  Fixes #18224.

  Sean Griffin

• Add bigint primary key support for MySQL.

  Example:

  create_table :foos, id: :bigint do |t|
  end
  

  Ryuta Kamizono

• Support for any type primary key.

  Fixes #14194.

  Ryuta Kamizono

• Dump the default nil for PostgreSQL UUID primary key.

  Ryuta Kamizono

• Add a :foreign_key option to references and associated migration methods. The model and migration generators now use this option, rather than the add_foreign_key form.

  Sean Griffin

• Don't raise when writing an attribute with an out-of-range datetime passed by the user.

  Grey Baker

• Replace deprecated ActiveRecord::Tasks::DatabaseTasks#load_schema with ActiveRecord::Tasks::DatabaseTasks#load_schema_for.

  Yves Senn

• Fixes bug with 'ActiveRecord::Type::Numeric' that causes negative values to be marked as having changed when set to the same negative value.

  Closes #18161.

  Daniel Fox

• Introduce force: :cascade option for create_table. Using this option will recreate tables even if they have dependent objects (like foreign keys). db/schema.rb now uses force: :cascade. This makes it possible to reload the schema when foreign keys are in place.

  Matthew Draper, Yves Senn

• db:schema:load and db:structure:load no longer purge the database before loading the schema. This is left for the user to do. db:test:prepare will still purge the database.

  Closes #17945.

  Yves Senn

• Fix undesirable RangeError by Type::Integer. Add Type::UnsignedInteger.

  Ryuta Kamizono

• Add foreign_type option to has_one and has_many association macros.

  This option enables to define the column name of associated object's type for polymorphic associations.

  Ulisses Almeida, Kassio Borges

• Remove deprecated behavior allowing nested arrays to be passed as query values.

  Melanie Gilman

• Deprecate passing a class as a value in a query. Users should pass strings instead.

  Melanie Gilman

• add_timestamps and remove_timestamps now properly reversible with options.

  Noam Gagliardi-Rabinovich

• ActiveRecord::ConnectionAdapters::ColumnDumper#column_spec and ActiveRecord::ConnectionAdapters::ColumnDumper#prepare_column_options no longer have a types argument. They should access connection#native_database_types directly.

  Yves Senn

Please check 4-2-stable for previous changes.