BUG: read_sql_table unable to read views (pandas-dev#54185)

Author: mroeschke

doc/source/whatsnew/v2.1.0.rst

@@ -528,6 +528,7 @@ I/O
 - Bug in :func:`read_hdf` not properly closing store after a ``IndexError`` is raised (:issue:`52781`)
 - Bug in :func:`read_html`, style elements were read into DataFrames (:issue:`52197`)
 - Bug in :func:`read_html`, tail texts were removed together with elements containing ``display:none`` style (:issue:`51629`)
+- Bug in :func:`read_sql_table` raising an exception when reading a view (:issue:`52969`)
 - Bug in :func:`read_sql` when reading multiple timezone aware columns with the same column name (:issue:`44421`)
 - Bug in :func:`read_xml` stripping whitespace in string data (:issue:`53811`)
 - Bug in :meth:`DataFrame.to_html` where ``colspace`` was incorrectly applied in case of multi index columns (:issue:`53885`)

pandas/io/sql.py

@@ -1655,7 +1655,7 @@ def read_table(
         SQLDatabase.read_query
 
         """
-        self.meta.reflect(bind=self.con, only=[table_name])
+        self.meta.reflect(bind=self.con, only=[table_name], views=True)
         table = SQLTable(table_name, self, index=index_col, schema=schema)
         if chunksize is not None:
             self.returns_generator = True
@@ -1989,7 +1989,9 @@ def get_table(self, table_name: str, schema: str | None = None) -> Table:
     def drop_table(self, table_name: str, schema: str | None = None) -> None:
         schema = schema or self.meta.schema
         if self.has_table(table_name, schema):
-            self.meta.reflect(bind=self.con, only=[table_name], schema=schema)
+            self.meta.reflect(
+                bind=self.con, only=[table_name], schema=schema, views=True
+            )
             with self.run_transaction():
                 self.get_table(table_name, schema).drop(bind=self.con)
             self.meta.clear()
@@ -2411,7 +2413,15 @@ def to_sql(
 
     def has_table(self, name: str, schema: str | None = None) -> bool:
         wld = "?"
-        query = f"SELECT name FROM sqlite_master WHERE type='table' AND name={wld};"
+        query = f"""
+        SELECT
+            name
+        FROM
+            sqlite_master
+        WHERE
+            type IN ('table', 'view')
+            AND name={wld};
+        """
 
         return len(self.execute(query, [name]).fetchall()) > 0
 

pandas/tests/io/test_sql.py

@@ -29,6 +29,7 @@
 from io import StringIO
 from pathlib import Path
 import sqlite3
+import uuid
 
 import numpy as np
 import pytest
@@ -932,6 +933,68 @@ def insert_on_conflict(table, conn, keys, data_iter):
         pandasSQL.drop_table("test_insert_conflict")
 
 
+@pytest.mark.db
+@pytest.mark.parametrize("conn", postgresql_connectable)
+def test_read_view_postgres(conn, request):
+    # GH 52969
+    conn = request.getfixturevalue(conn)
+
+    from sqlalchemy.engine import Engine
+    from sqlalchemy.sql import text
+
+    table_name = f"group_{uuid.uuid4().hex}"
+    view_name = f"group_view_{uuid.uuid4().hex}"
+
+    sql_stmt = text(
+        f"""
+    CREATE TABLE {table_name} (
+        group_id INTEGER,
+        name TEXT
+    );
+    INSERT INTO {table_name} VALUES
+        (1, 'name');
+    CREATE VIEW {view_name}
+    AS
+    SELECT * FROM {table_name};
+    """
+    )
+    if isinstance(conn, Engine):
+        with conn.connect() as con:
+            with con.begin():
+                con.execute(sql_stmt)
+    else:
+        with conn.begin():
+            conn.execute(sql_stmt)
+    result = read_sql_table(view_name, conn)
+    expected = DataFrame({"group_id": [1], "name": "name"})
+    tm.assert_frame_equal(result, expected)
+
+
+def test_read_view_sqlite(sqlite_buildin):
+    # GH 52969
+    create_table = """
+CREATE TABLE groups (
+   group_id INTEGER,
+   name TEXT
+);
+"""
+    insert_into = """
+INSERT INTO groups VALUES
+    (1, 'name');
+"""
+    create_view = """
+CREATE VIEW group_view
+AS
+SELECT * FROM groups;
+"""
+    sqlite_buildin.execute(create_table)
+    sqlite_buildin.execute(insert_into)
+    sqlite_buildin.execute(create_view)
+    result = pd.read_sql("SELECT * FROM group_view", sqlite_buildin)
+    expected = DataFrame({"group_id": [1], "name": "name"})
+    tm.assert_frame_equal(result, expected)
+
+
 def test_execute_typeerror(sqlite_iris_engine):
     with pytest.raises(TypeError, match="pandas.io.sql.execute requires a connection"):
         with tm.assert_produces_warning(