BUG: fix is_named_tuple for objects that are not subclass of tuple pandas-dev#40682 (pandas-dev#43253)

Author: fangchenli

doc/source/whatsnew/v1.4.0.rst

@@ -376,6 +376,7 @@ I/O
 - Bug in :func:`read_csv` with multi-header input and arguments referencing column names as tuples (:issue:`42446`)
 - Bug in :func:`read_fwf`, where difference in lengths of ``colspecs`` and ``names`` was not raising ``ValueError`` (:issue:`40830`)
 - Bug in :func:`Series.to_json` and :func:`DataFrame.to_json` where some attributes were skipped when serialising plain Python objects to JSON (:issue:`42768`, :issue:`33043`)
+- Column headers are dropped when constructing a :class:`DataFrame` from a sqlalchemy's ``Row`` object (:issue:`40682`)
 -
 
 Period

pandas/core/dtypes/inference.py

@@ -315,7 +315,7 @@ def is_named_tuple(obj) -> bool:
     >>> is_named_tuple((1, 2))
     False
     """
-    return isinstance(obj, tuple) and hasattr(obj, "_fields")
+    return isinstance(obj, abc.Sequence) and hasattr(obj, "_fields")
 
 
 def is_hashable(obj) -> bool:

pandas/tests/io/test_sql.py

@@ -2189,6 +2189,44 @@ def test_bigint_warning(self):
         with tm.assert_produces_warning(None):
             sql.read_sql_table("test_bigintwarning", self.conn)
 
+    def test_row_object_is_named_tuple(self):
+        # GH 40682
+        # Test for the is_named_tuple() function
+        # Placed here due to its usage of sqlalchemy
+
+        from sqlalchemy import (
+            Column,
+            Integer,
+            String,
+        )
+        from sqlalchemy.orm import sessionmaker
+
+        if _gt14():
+            from sqlalchemy.orm import declarative_base
+        else:
+            from sqlalchemy.ext.declarative import declarative_base
+
+        BaseModel = declarative_base()
+
+        class Test(BaseModel):
+            __tablename__ = "test_frame"
+            id = Column(Integer, primary_key=True)
+            foo = Column(String(50))
+
+        BaseModel.metadata.create_all(self.conn)
+        Session = sessionmaker(bind=self.conn)
+        session = Session()
+
+        df = DataFrame({"id": [0, 1], "foo": ["hello", "world"]})
+        df.to_sql("test_frame", con=self.conn, index=False, if_exists="replace")
+
+        session.commit()
+        foo = session.query(Test.id, Test.foo)
+        df = DataFrame(foo)
+        session.close()
+
+        assert list(df.columns) == ["id", "foo"]
+
 
 class _TestMySQLAlchemy:
     """