fix: Date→datetime and Boolean→int via colspecs TypeDecorator

Previous output_converter approach didn't work because the GaussDB ODBC
driver already returns Python objects (datetime/int), not raw bytes —
pyodbc's add_output_converter only fires on raw bytes.

New approach: register _GaussDBOdbcDate and _GaussDBOdbcBoolean as
TypeDecorator subclasses in both colspecs (for user-defined columns)
and ischema_names (for reflected columns), ensuring result processors
fire on ALL Date/Boolean columns regardless of how they were defined.

Author: jarrenL

src/gaussdb_sqlalchemy/base.py

@@ -10,6 +10,9 @@
 from sqlalchemy.dialects.postgresql.base import PGDDLCompiler
 from sqlalchemy.dialects.postgresql.base import PGIdentifierPreparer
 from sqlalchemy.dialects.postgresql.base import PGTypeCompiler
+from sqlalchemy.dialects.postgresql.base import PGExecutionContext
+from sqlalchemy.dialects.postgresql import DATE as _PG_DATE
+from sqlalchemy.dialects.postgresql import BOOLEAN as _PG_BOOLEAN
 from sqlalchemy.exc import NoSuchTableError
 from sqlalchemy import schema as sa_schema
 from sqlalchemy import types as sqltypes
@@ -19,6 +22,56 @@
 from sqlalchemy.sql import operators
 from sqlalchemy.sql.compiler import OPERATORS
 
+import datetime as _dt
+
+
+class _GaussDBOdbcDate(sqltypes.TypeDecorator):
+    """Date type that normalises ODBC driver datetime returns to date.
+
+    The GaussDB ODBC driver on Windows returns ``datetime.datetime``
+    for DATE columns instead of ``datetime.date``.  pyodbc's
+    ``add_output_converter`` cannot fix this because the driver already
+    converted the raw bytes to a Python object before pyodbc sees it.
+
+    This TypeDecorator wraps the standard PG DATE type and adds a
+    result processor that strips the time component.
+    """
+
+    impl = _PG_DATE
+    cache_ok = True
+
+    def process_result_value(self, value, dialect):
+        if value is None:
+            return value
+        if isinstance(value, _dt.datetime):
+            return value.date()
+        if isinstance(value, _dt.date):
+            return value
+        return value
+
+
+class _GaussDBOdbcBoolean(sqltypes.TypeDecorator):
+    """Boolean type that normalises ODBC driver integer returns to bool.
+
+    The GaussDB ODBC driver returns ``int`` (1/0) for boolean columns.
+    SQLAlchemy's default ``Boolean.result_processor`` is a no-op when
+    ``supports_native_boolean`` is True, so we must add our own.
+    """
+
+    impl = _PG_BOOLEAN
+    cache_ok = True
+
+    def process_result_value(self, value, dialect):
+        if value is None:
+            return value
+        if isinstance(value, bool):
+            return value
+        if isinstance(value, (bytes, bytearray)):
+            value = value.decode("utf-8")
+        if isinstance(value, str):
+            return value.strip().lower() in ("1", "t", "true", "y")
+        return bool(value)
+
 
 class GaussDBCompiler(PGCompiler):
     def visit_concat_op_binary(self, binary, operator_, **kw):
@@ -173,9 +226,6 @@ def visit_large_binary(self, type_, **kw):
         return super().visit_large_binary(type_, **kw)
 
 
-from sqlalchemy.dialects.postgresql.base import PGExecutionContext
-
-
 class GaussDBMExecutionContext(PGExecutionContext):
     def get_lastrowid(self):
         try:
@@ -218,9 +268,13 @@ class GaussDBDialect(PGDialect):
     gaussdb_compatibility = None
 
     # Register GaussDB M-compat binary types for reflection.
+    # Override date/boolean with ODBC-aware variants that normalise
+    # driver returns (datetime→date, int→bool).
     ischema_names = dict(PGDialect.ischema_names)
     ischema_names["blob"] = LargeBinary
     ischema_names["longblob"] = LargeBinary
+    ischema_names["date"] = _GaussDBOdbcDate
+    ischema_names["boolean"] = _GaussDBOdbcBoolean
 
     def initialize(self, connection):
         super().initialize(connection)

src/gaussdb_sqlalchemy/odbc.py

@@ -23,11 +23,19 @@
 
 from . import odbc_dbapi
 from .alembic import register_alembic_impl
-from .base import GaussDBDialect
+from .base import GaussDBDialect, _GaussDBOdbcDate, _GaussDBOdbcBoolean
 
 
 register_alembic_impl()
 
+
+# Inherit PG colspecs and override Date/Boolean with ODBC-aware variants.
+# This ensures that BOTH user-defined Column(Date) and reflected columns
+# get the result processors that normalise ODBC driver returns.
+_cspecs = dict(GaussDBDialect.colspecs)
+_cspecs[sqltypes.Date] = _GaussDBOdbcDate
+_cspecs[sqltypes.Boolean] = _GaussDBOdbcBoolean
+
 # Query-string keys that are not forwarded as ODBC connection attributes.
 _CONTROL_KEYS = {"driver", "dsn"}
 
@@ -38,6 +46,7 @@ class GaussDBDialect_odbc(GaussDBDialect):
     driver = "odbc"
     default_paramstyle = "qmark"
     supports_statement_cache = True
+    colspecs = _cspecs
 
     @classmethod
     def import_dbapi(cls):