- The typing system now handles the task of rendering "literal bind" values,

e.g. values that are normally bound parameters but due to context must
be rendered as strings, typically within DDL constructs such as
CHECK constraints and indexes (note that "literal bind" values
become used by DDL as of :ticket:`2742`).  A new method
:meth:`.TypeEngine.literal_processor` serves as the base, and
:meth:`.TypeDecorator.process_literal_param` is added to allow wrapping
of a native literal rendering method. [ticket:2838]
- enhance _get_colparams so that we can send flags like literal_binds into
INSERT statements
- add support in PG for inspecting standard_conforming_strings
- add a new series of roundtrip tests based on INSERT of literal plus SELECT
for basic literal rendering in dialect suite

1 files changed, 16 insertions, 9 deletions

diff --git a/lib/sqlalchemy/dialects/postgresql/base.py b/lib/sqlalchemy/dialects/postgresql/base.py
index fdb6e3b4a..55c6b315a 100644
--- a/lib/sqlalchemy/dialects/postgresql/base.py
+++ b/lib/sqlalchemy/dialects/postgresql/base.py
@@ -210,7 +210,7 @@ import re
 
 from ... import sql, schema, exc, util
 from ...engine import default, reflection
-from ...sql import compiler, expression, util as sql_util, operators
+from ...sql import compiler, expression, operators
 from ... import types as sqltypes
 
 try:
@@ -954,25 +954,30 @@ class PGCompiler(compiler.SQLCompiler):
 
     def visit_ilike_op_binary(self, binary, operator, **kw):
         escape = binary.modifiers.get("escape", None)
+
         return '%s ILIKE %s' % \
                 (self.process(binary.left, **kw),
                     self.process(binary.right, **kw)) \
-                + (escape and
-                        (' ESCAPE ' + self.render_literal_value(escape, None))
-                        or '')
+            + (
+                ' ESCAPE ' +
+                self.render_literal_value(escape, sqltypes.STRINGTYPE)
+                if escape else ''
+            )
 
     def visit_notilike_op_binary(self, binary, operator, **kw):
         escape = binary.modifiers.get("escape", None)
         return '%s NOT ILIKE %s' % \
                 (self.process(binary.left, **kw),
                     self.process(binary.right, **kw)) \
-                + (escape and
-                        (' ESCAPE ' + self.render_literal_value(escape, None))
-                        or '')
+            + (
+                ' ESCAPE ' +
+                self.render_literal_value(escape, sqltypes.STRINGTYPE)
+                if escape else ''
+            )
 
     def render_literal_value(self, value, type_):
         value = super(PGCompiler, self).render_literal_value(value, type_)
-        # TODO: need to inspect "standard_conforming_strings"
+
         if self.dialect._backslash_escapes:
             value = value.replace('\\', '\\\\')
         return value
@@ -1357,7 +1362,6 @@ class PGDialect(default.DefaultDialect):
     inspector = PGInspector
     isolation_level = None
 
-    # TODO: need to inspect "standard_conforming_strings"
     _backslash_escapes = True
 
     def __init__(self, isolation_level=None, **kwargs):
@@ -1379,6 +1383,9 @@ class PGDialect(default.DefaultDialect):
         # http://www.postgresql.org/docs/9.3/static/release-9-2.html#AEN116689
         self.supports_smallserial = self.server_version_info >= (9, 2)
 
+        self._backslash_escapes = connection.scalar(
+                                    "show standard_conforming_strings"
+                                    ) == 'off'
 
     def on_connect(self):
         if self.isolation_level is not None: