From af0e59ff16a2a02ec5dc1195212236e63fd941a7 Mon Sep 17 00:00:00 2001 From: Mike Bayer Date: Thu, 7 May 2020 10:53:15 -0400 Subject: Disable "check unicode returns" under Python 3 Disabled the "unicode returns" check that runs on dialect startup when running under Python 3, which for many years has occurred in order to test the current DBAPI's behavior for whether or not it returns Python Unicode or Py2K strings for the VARCHAR and NVARCHAR datatypes. The check still occurs by default under Python 2, however the mechanism to test the behavior will be removed in SQLAlchemy 2.0 when Python 2 support is also removed. This logic was very effective when it was needed, however now that Python 3 is standard, all DBAPIs are expected to return Python 3 strings for character datatypes. In the unlikely case that a third party DBAPI does not support this, the conversion logic within :class:`.String` is still available and the third party dialect may specify this in its upfront dialect flags by setting the dialect level flag ``returns_unicode_strings`` to one of :attr:`.String.RETURNS_CONDITIONAL` or :attr:`.String.RETURNS_BYTES`, both of which will enable Unicode conversion even under Python 3. As part of this change, disabling testing of the doctest tutorials under Python 2. Fixes: #5315 Change-Id: I1260e894611409d3b7fe1a92bd90c52043bbcf19 --- lib/sqlalchemy/engine/default.py | 21 ++++++++++++++++----- 1 file changed, 16 insertions(+), 5 deletions(-) (limited to 'lib/sqlalchemy/engine/default.py') diff --git a/lib/sqlalchemy/engine/default.py b/lib/sqlalchemy/engine/default.py index 20f731116..d9b4cdda6 100644 --- a/lib/sqlalchemy/engine/default.py +++ b/lib/sqlalchemy/engine/default.py @@ -94,12 +94,12 @@ class DefaultDialect(interfaces.Dialect): if util.py3k: supports_unicode_statements = True supports_unicode_binds = True - returns_unicode_strings = True + returns_unicode_strings = sqltypes.String.RETURNS_UNICODE description_encoding = None else: supports_unicode_statements = False supports_unicode_binds = False - returns_unicode_strings = False + returns_unicode_strings = sqltypes.String.RETURNS_UNKNOWN description_encoding = "use_encoding" name = "default" @@ -325,7 +325,14 @@ class DefaultDialect(interfaces.Dialect): except NotImplementedError: self.default_isolation_level = None - self.returns_unicode_strings = self._check_unicode_returns(connection) + if self.returns_unicode_strings is sqltypes.String.RETURNS_UNKNOWN: + if util.py3k: + raise exc.InvalidRequestError( + "RETURNS_UNKNOWN is unsupported in Python 3" + ) + self.returns_unicode_strings = self._check_unicode_returns( + connection + ) if ( self.description_encoding is not None @@ -415,9 +422,13 @@ class DefaultDialect(interfaces.Dialect): results = {check_unicode(test) for test in tests} if results.issuperset([True, False]): - return "conditional" + return sqltypes.String.RETURNS_CONDITIONAL else: - return results == {True} + return ( + sqltypes.String.RETURNS_UNICODE + if results == {True} + else sqltypes.String.RETURNS_BYTES + ) def _check_unicode_description(self, connection): # all DBAPIs on Py2K return cursor.description as encoded -- cgit v1.2.1