TableValuedAlias generation fixes

Fixed bug in newly implemented
:paramref:`.FunctionElement.table_valued.joins_implicitly` feature where
the parameter would not automatically propagate from the original
:class:`.TableValuedAlias` object to the secondary object produced when
calling upon :meth:`.TableValuedAlias.render_derived` or
:meth:`.TableValuedAlias.alias`.

Additionally repaired these issues in :class:`.TableValuedAlias`:

* repaired a potential memory issue which could occur when
repeatedly calling :meth:`.TableValuedAlias.render_derived` against
successive copies of the same object (for .alias(), we currently
have to still continue chaining from the previous element.  not sure
if this can be improved but this is standard behavior for .alias()
elsewhere)
* repaired issue where the individual element types would be lost when
calling upon :meth:`.TableValuedAlias.render_derived` or
:meth:`.TableValuedAlias.alias`.

Fixes: #7890
Change-Id: Ie5120c7ff1e5c1bba5aaf77c782a51c637860208

1 files changed, 25 insertions, 1 deletions

diff --git a/test/sql/test_functions.py b/test/sql/test_functions.py
index e08526419..c055bc150 100644
--- a/test/sql/test_functions.py
+++ b/test/sql/test_functions.py
@@ -26,7 +26,6 @@ from sqlalchemy import Table
 from sqlalchemy import testing
 from sqlalchemy import Text
 from sqlalchemy import true
-from sqlalchemy import types as sqltypes
 from sqlalchemy.dialects import mysql
 from sqlalchemy.dialects import oracle
 from sqlalchemy.dialects import postgresql
@@ -37,6 +36,7 @@ from sqlalchemy.sql import functions
 from sqlalchemy.sql import LABEL_STYLE_TABLENAME_PLUS_COL
 from sqlalchemy.sql import operators
 from sqlalchemy.sql import quoted_name
+from sqlalchemy.sql import sqltypes
 from sqlalchemy.sql import table
 from sqlalchemy.sql.compiler import BIND_TEMPLATES
 from sqlalchemy.sql.functions import FunctionElement
@@ -1425,6 +1425,30 @@ class TableValuedCompileTest(fixtures.TestBase, AssertsCompiledSQL):
             "LEFT OUTER JOIN b ON unnested.unnested = b.ref",
         )
 
+    def test_render_derived_maintains_tableval_type(self):
+        fn = func.json_something()
+
+        tv = fn.table_valued(column("x", String))
+
+        eq_(tv.column.type, testing.eq_type_affinity(sqltypes.TableValueType))
+        eq_(tv.column.type._elements[0].type, testing.eq_type_affinity(String))
+
+        tv = tv.render_derived()
+        eq_(tv.column.type, testing.eq_type_affinity(sqltypes.TableValueType))
+        eq_(tv.column.type._elements[0].type, testing.eq_type_affinity(String))
+
+    def test_alias_maintains_tableval_type(self):
+        fn = func.json_something()
+
+        tv = fn.table_valued(column("x", String))
+
+        eq_(tv.column.type, testing.eq_type_affinity(sqltypes.TableValueType))
+        eq_(tv.column.type._elements[0].type, testing.eq_type_affinity(String))
+
+        tv = tv.alias()
+        eq_(tv.column.type, testing.eq_type_affinity(sqltypes.TableValueType))
+        eq_(tv.column.type._elements[0].type, testing.eq_type_affinity(String))
+
     def test_star_with_ordinality(self):
         """
         SELECT * FROM generate_series(4,1,-1) WITH ORDINALITY;