add explicit REGCONFIG, pg full text functions

Added support for explicit use of PG full text functions with asyncpg and
psycopg (SQLAlchemy 2.0 only), with regards to the ``REGCONFIG`` type cast
for the first argument, which previously would be incorrectly cast to a
VARCHAR, causing failures on these dialects that rely upon explicit type
casts. This includes support for :class:`_postgresql.to_tsvector`,
:class:`_postgresql.to_tsquery`, :class:`_postgresql.plainto_tsquery`,
:class:`_postgresql.phraseto_tsquery`,
:class:`_postgresql.websearch_to_tsquery`,
:class:`_postgresql.ts_headline`, each of which will determine based on
number of arguments passed if the first string argument should be
interpreted as a PostgreSQL "REGCONFIG" value; if so, the argument is typed
using a newly added type object :class:`_postgresql.REGCONFIG` which is
then explicitly cast in the SQL expression.

Fixes: #8977
Change-Id: Ib36698a984fd4194bd6e0eb663105f790f3db7d3

1 files changed, 6 insertions, 0 deletions

diff --git a/lib/sqlalchemy/dialects/postgresql/asyncpg.py b/lib/sqlalchemy/dialects/postgresql/asyncpg.py
index b8f614eba..3c1eaf918 100644
--- a/lib/sqlalchemy/dialects/postgresql/asyncpg.py
+++ b/lib/sqlalchemy/dialects/postgresql/asyncpg.py
@@ -142,6 +142,7 @@ from .base import PGDialect
 from .base import PGExecutionContext
 from .base import PGIdentifierPreparer
 from .base import REGCLASS
+from .base import REGCONFIG
 from ... import exc
 from ... import pool
 from ... import util
@@ -160,6 +161,10 @@ class AsyncpgString(sqltypes.String):
     render_bind_cast = True
 
 
+class AsyncpgREGCONFIG(REGCONFIG):
+    render_bind_cast = True
+
+
 class AsyncpgTime(sqltypes.Time):
     render_bind_cast = True
 
@@ -899,6 +904,7 @@ class PGDialect_asyncpg(PGDialect):
         PGDialect.colspecs,
         {
             sqltypes.String: AsyncpgString,
+            REGCONFIG: AsyncpgREGCONFIG,
             sqltypes.Time: AsyncpgTime,
             sqltypes.Date: AsyncpgDate,
             sqltypes.DateTime: AsyncpgDateTime,