From f7731e21978d6ce79d90677d29440309ed8babf8 Mon Sep 17 00:00:00 2001
From: jbrockmendel <jbrockmendel@gmail.com>
Date: Tue, 16 Mar 2021 13:30:53 -0700
Subject: [PATCH] Backport PR #40471: compat: sqlalchemy deprecations

---
 pandas/io/sql.py            | 42 ++++++++++++++++++++++++++++++-------
 pandas/tests/io/test_sql.py | 25 ++++++++++++++++------
 2 files changed, 54 insertions(+), 13 deletions(-)

diff --git a/pandas/io/sql.py b/pandas/io/sql.py
index 02b06b164a2a1..b93f097b93441 100644
--- a/pandas/io/sql.py
+++ b/pandas/io/sql.py
@@ -5,6 +5,7 @@
 
 from contextlib import contextmanager
 from datetime import date, datetime, time
+from distutils.version import LooseVersion
 from functools import partial
 import re
 from typing import Iterator, List, Optional, Union, overload
@@ -55,6 +56,16 @@ def _is_sqlalchemy_connectable(con):
         return False
 
 
+def _gt14() -> bool:
+    """
+    Check if sqlalchemy.__version__ is at least 1.4.0, when several
+    deprecations were made.
+    """
+    import sqlalchemy
+
+    return LooseVersion(sqlalchemy.__version__) >= LooseVersion("1.4.0")
+
+
 def _convert_params(sql, params):
     """Convert SQL and params args to DBAPI2.0 compliant format."""
     args = [sql]
@@ -715,7 +726,10 @@ def sql_schema(self):
 
     def _execute_create(self):
         # Inserting table into database, add to MetaData object
-        self.table = self.table.tometadata(self.pd_sql.meta)
+        if _gt14():
+            self.table = self.table.to_metadata(self.pd_sql.meta)
+        else:
+            self.table = self.table.tometadata(self.pd_sql.meta)
         self.table.create()
 
     def create(self):
@@ -1409,9 +1423,17 @@ def to_sql(
             # Only check when name is not a number and name is not lower case
             engine = self.connectable.engine
             with self.connectable.connect() as conn:
-                table_names = engine.table_names(
-                    schema=schema or self.meta.schema, connection=conn
-                )
+                if _gt14():
+                    from sqlalchemy import inspect
+
+                    insp = inspect(conn)
+                    table_names = insp.get_table_names(
+                        schema=schema or self.meta.schema
+                    )
+                else:
+                    table_names = engine.table_names(
+                        schema=schema or self.meta.schema, connection=conn
+                    )
             if name not in table_names:
                 msg = (
                     f"The provided table name '{name}' is not found exactly as "
@@ -1426,9 +1448,15 @@ def tables(self):
         return self.meta.tables
 
     def has_table(self, name, schema=None):
-        return self.connectable.run_callable(
-            self.connectable.dialect.has_table, name, schema or self.meta.schema
-        )
+        if _gt14():
+            import sqlalchemy as sa
+
+            insp = sa.inspect(self.connectable)
+            return insp.has_table(name, schema or self.meta.schema)
+        else:
+            return self.connectable.run_callable(
+                self.connectable.dialect.has_table, name, schema or self.meta.schema
+            )
 
     def get_table(self, table_name, schema=None):
         schema = schema or self.meta.schema
diff --git a/pandas/tests/io/test_sql.py b/pandas/tests/io/test_sql.py
index 16d4bc65094f8..f8a8b662f2652 100644
--- a/pandas/tests/io/test_sql.py
+++ b/pandas/tests/io/test_sql.py
@@ -44,10 +44,11 @@
 import pandas._testing as tm
 
 import pandas.io.sql as sql
-from pandas.io.sql import read_sql_query, read_sql_table
+from pandas.io.sql import _gt14, read_sql_query, read_sql_table
 
 try:
     import sqlalchemy
+    from sqlalchemy import inspect
     from sqlalchemy.ext import declarative
     from sqlalchemy.orm import session as sa_session
     import sqlalchemy.schema
@@ -1331,7 +1332,11 @@ def test_create_table(self):
         pandasSQL = sql.SQLDatabase(temp_conn)
         pandasSQL.to_sql(temp_frame, "temp_frame")
 
-        assert temp_conn.has_table("temp_frame")
+        if _gt14():
+            insp = inspect(temp_conn)
+            assert insp.has_table("temp_frame")
+        else:
+            assert temp_conn.has_table("temp_frame")
 
     def test_drop_table(self):
         temp_conn = self.connect()
@@ -1343,11 +1348,18 @@ def test_drop_table(self):
         pandasSQL = sql.SQLDatabase(temp_conn)
         pandasSQL.to_sql(temp_frame, "temp_frame")
 
-        assert temp_conn.has_table("temp_frame")
+        if _gt14():
+            insp = inspect(temp_conn)
+            assert insp.has_table("temp_frame")
+        else:
+            assert temp_conn.has_table("temp_frame")
 
         pandasSQL.drop_table("temp_frame")
 
-        assert not temp_conn.has_table("temp_frame")
+        if _gt14():
+            assert not insp.has_table("temp_frame")
+        else:
+            assert not temp_conn.has_table("temp_frame")
 
     def test_roundtrip(self):
         self._roundtrip()
@@ -1689,9 +1701,10 @@ def test_nan_string(self):
         tm.assert_frame_equal(result, df)
 
     def _get_index_columns(self, tbl_name):
-        from sqlalchemy.engine import reflection
+        from sqlalchemy import inspect
+
+        insp = inspect(self.conn)
 
-        insp = reflection.Inspector.from_engine(self.conn)
         ixs = insp.get_indexes(tbl_name)
         ixs = [i["column_names"] for i in ixs]
         return ixs