1.2.0

Released: December 27, 2017

• [bug] [sql] Fixed bug where __repr__ of ColumnDefault would fail
  if the argument were a tuple. Pull request courtesy Nicolas Caniart.

  This change is also backported to: 1.1.15

  References: #4126

• [bug] [declarative] [orm] Fixed bug where a descriptor that is elsewhere a mapped column
  or relationship within a hierarchy based on AbstractConcreteBase
  would be referred towards during a refresh operation, causing an error
  as the attribute is not mapped as a mapper property.
  A similar issue can arise for other attributes like the "type" column
  added by AbstractConcreteBase if the class fails to include
  "concrete=True" in its mapper, however the check here should also
  prevent that scenario from causing a problem.

  This change is also backported to: 1.1.15

  References: #4124

• [bug] [ext] [orm] Fixed bug where the association proxy would inadvertently link itself
  to an AliasedClass object if it were called first with
  the AliasedClass as a parent, causing errors upon subsequent
  usage.

  This change is also backported to: 1.1.15

  References: #4116

• [bug] [mysql] MySQL 5.7.20 now warns for use of the @tx_isolation variable; a version
  check is now performed and uses @transaction_isolation instead
  to prevent this warning.

  This change is also backported to: 1.1.15

  References: #4120

• [feature] [orm] Added a new data member to the identity key tuple
  used by the ORM's identity map, known as the
  "identity_token". This token defaults to None but
  may be used by database sharding schemes to differentiate
  objects in memory with the same primary key that come
  from different databases. The horizontal sharding
  extension integrates this token applying the shard
  identifier to it, thus allowing primary keys to be
  duplicated across horizontally sharded backends.

  References: #4137

• [bug] [mysql] Fixed regression from issue 1.2.0b3 where "MariaDB" version comparison can
  fail for some particular MariaDB version strings under Python 3.

  References: #4115

• [enhancement] [sql] Implemented "DELETE..FROM" syntax for PostgreSQL, MySQL, MS SQL Server
  (as well as within the unsupported Sybase dialect) in a manner similar
  to how "UPDATE..FROM" works. A DELETE statement that refers to more than
  one table will switch into "multi-table" mode and render the appropriate
  "USING" or multi-table "FROM" clause as understood by the database.
  Pull request courtesy Pieter Mulder.

  References: #959

• [bug] [sql] Reworked the new "autoescape" feature introduced in
  change_2694 in 1.2.0b2 to be fully automatic; the escape
  character now defaults to a forwards slash "/" and
  is applied to percent, underscore, as well as the escape
  character itself, for fully automatic escaping. The
  character can also be changed using the "escape" parameter.

  References: #2694

• [bug] [sql] Fixed bug where the Table.tometadata() method would not properly
  accommodate Index objects that didn't consist of simple
  column expressions, such as indexes against a text() construct,
  indexes that used SQL expressions or func, etc. The routine
  now copies expressions fully to a new Index object while
  substituting all table-bound Column objects for those
  of the target table.

  References: #4147

• [bug] [sql] Changed the "visit name" of ColumnElement from "column" to
  "column_element", so that when this element is used as the basis for a
  user-defined SQL element, it is not assumed to behave like a table-bound
  ColumnClause when processed by various SQL traversal utilities,
  as are commonly used by the ORM.

  References: #4142

• [bug] [ext] [sql] Fixed issue in ARRAY datatype which is essentially the same
  issue as that of #3832, except not a regression, where
  column attachment events on top of ARRAY would not fire
  correctly, thus interfering with systems which rely upon this. A key
  use case that was broken by this is the use of mixins to declare
  columns that make use of MutableList.as_mutable().

  References: #4141

• [engine] [feature] The "password" attribute of the url.URL object can now be
  any user-defined or user-subclassed string object that responds to the
  Python str() builtin. The object passed will be maintained as the
  datamember url.URL.password_original and will be consulted
  when the url.URL.password attribute is read to produce the
  string value.

  References: #4089

• [bug] [orm] Fixed bug in contains_eager() query option where making use of a
  path that used PropComparator.of_type() to refer to a subclass
  across more than one level of joins would also require that the "alias"
  argument were provided with the same subtype in order to avoid adding
  unwanted FROM clauses to the query; additionally, using
  contains_eager() across subclasses that use aliased() objects
  of subclasses as the PropComparator.of_type() argument will also
  render correctly.

  References: #4130

• [feature] [postgresql] Added new postgresql.MONEY datatype. Pull request courtesy
  Cleber J Santos.

• [bug] [sql] Fixed bug in new "expanding bind parameter" feature whereby if multiple
  params were used in one statement, the regular expression would not
  match the parameter name correctly.

  References: #4140

• [enhancement] [ext] Added new method baked.Result.with_post_criteria() to baked
  query system, allowing non-SQL-modifying transformations to take place
  after the query has been pulled from the cache. Among other things,
  this method can be used with horizontal_shard.ShardedQuery
  to set the shard identifier. horizontal_shard.ShardedQuery
  has also been modified such that its ShardedQuery.get() method
  interacts correctly with that of baked.Result.

  References: #4135

• [bug] [oracle] Added some additional rules to fully handle Decimal('Infinity'),
  Decimal('-Infinity') values with cx_Oracle numerics when using
  asdecimal=True.

  References: #4064

• [bug] [mssql] Fixed bug where sqltypes.BINARY and sqltypes.VARBINARY datatypes
  would not include correct bound-value handlers for pyodbc,
  which allows the pyodbc.NullParam value to be passed that
  helps with FreeTDS.

  References: #4121

• [feature] [misc] Added a new errors section to the documentation with background
  about common error messages. Selected exceptions within SQLAlchemy
  will include a link in their string output to the relevant section
  within this page.

• [bug] [orm] The Query.exists() method will now disable eager loaders for when
  the query is rendered. Previously, joined-eager load joins would be rendered
  unnecessarily as well as subquery eager load queries would be needlessly
  generated. The new behavior matches that of the Query.subquery()
  method.

  References: #4032