frontend: use context manager for SQLAlchemy execute

See #3130

    AttributeError: 'Engine' object has no attribute 'execute'

And also use text for raw SQL commands

    Use the text() construct, or the Connection.exec_driver_sql()
    method to invoke a driver-level SQL string.

And finially setting `future=True` which is going to be passed to
`create_engine` by Flask-SQLAlchemy to ensure compatibility between
SQLAlchemy 1.x and 2.0. Otherwise we would get

    AttributeError: 'Connection' object has no attribute 'commit'

frontend/coprs_frontend/coprs/__init__.py

@@ -41,7 +41,8 @@
 
 session = Session(app)
 
-db = SQLAlchemy(app)
+# Set `future=True` to ensure compatibility between SQLAlchemy 1.x and 2.0
+db = SQLAlchemy(app, engine_options={"future": True})
 
 @contextmanager
 def db_session_scope():

frontend/coprs_frontend/coprs/logic/batches_logic.py

@@ -6,6 +6,7 @@
 import anytree
 import backoff
 
+from sqlalchemy import text
 from sqlalchemy.exc import SQLAlchemyError
 from sqlalchemy_utils.functions import quote as sa_quote
 from coprs import app, db, cache
@@ -28,9 +29,10 @@ def _lock_table(table):
     # EXCLUSIVE mode locks the whole table for write operations
     # (while reading is not blocked) until the end of the transaction
     # (commit / rollback)
-    db.session.execute("LOCK TABLE {} IN EXCLUSIVE MODE;".format(
-        sa_quote(db.engine, table),
-    ))
+    with db.engine.connect() as connection:
+        connection.execute("LOCK TABLE {} IN EXCLUSIVE MODE;".format(
+            sa_quote(db.engine, table),
+        ))
 
 
 @contextlib.contextmanager

frontend/coprs_frontend/coprs/logic/builds_logic.py

@@ -166,7 +166,13 @@ def get_pending_jobs_bucket(cls, start, end):
                 AND NOT build.canceled
         """)
 
-        res = db.engine.execute(query, start=start, end=end, status=StatusEnum("pending"))
+        with db.engine.connect() as connection:
+            params = {
+                "start": start,
+                "end": end,
+                "status": StatusEnum("pending")
+            }
+            res = connection.execute(query, params)
         return res.first().result
 
     @classmethod
@@ -181,7 +187,13 @@ def get_running_jobs_bucket(cls, start, end):
                 -- builds that have ended_on=NULL
         """)
 
-        res = db.engine.execute(query, start=start, end=end, status=StatusEnum("running"))
+        with db.engine.connect() as connection:
+            params = {
+                "start": start,
+                "end": end,
+                "status": StatusEnum("running")
+            }
+            res = connection.execute(query, params)
         return res.first().result
 
     @classmethod

frontend/coprs_frontend/coprs/whoosheers.py

@@ -4,6 +4,7 @@
 
 from subprocess import Popen, PIPE
 from flask_whooshee import AbstractWhoosheer
+from sqlalchemy import text
 
 from coprs import app
 from coprs import models
@@ -78,25 +79,28 @@ def delete_package(cls, writer, package):
     def get_chroot_info(cls, copr):
         # NOTE: orm db session for Copr model is already committed at the point insert_*/update_* methods are called.
         # Hence we use db.engine directly (for a new session).
-        result = db.engine.execute(
-            """
-            SELECT os_release, os_version, arch
-            FROM mock_chroot
-            JOIN copr_chroot ON copr_chroot.mock_chroot_id=mock_chroot.id
-            WHERE copr_chroot.copr_id={0}
-            """.format(copr.id)
-        )
+
+        with db.engine.connect() as connection:
+            result = connection.execute(text(
+                """
+                SELECT os_release, os_version, arch
+                FROM mock_chroot
+                JOIN copr_chroot ON copr_chroot.mock_chroot_id=mock_chroot.id
+                WHERE copr_chroot.copr_id={0}
+                """.format(copr.id)
+            ))
         return ["{}-{}-{}".format(t[0], t[1], t[2]) for t in result.fetchall()]
 
     @classmethod
     def get_package_names(cls, copr):
-        result = db.engine.execute(
-            """
-            SELECT name
-            FROM package
-            WHERE copr_id={0}
-            """.format(copr.id)
-        )
+        with db.engine.connect() as connection:
+            result = connection.execute(text(
+                """
+                SELECT name
+                FROM package
+                WHERE copr_id={0}
+                """.format(copr.id)
+            ))
         return [row[0] for row in result.fetchall()]
 
     @classmethod
@@ -105,12 +109,13 @@ def on_commit(cls, app, changes):
         for change in changes:
             if change[0].__class__ in cls.models:
                 copr_id = change[0].get_search_related_copr_id()
-                db.engine.execute(
-                    """
-                    UPDATE copr SET latest_indexed_data_update = {0}
-                    WHERE copr.id = {1}
-                    """.format(int(time.time()), copr_id)
-                )
+                with db.engine.connect() as connection:
+                    connection.execute(text(
+                        """
+                        UPDATE copr SET latest_indexed_data_update = {0}
+                        WHERE copr.id = {1}
+                        """.format(int(time.time()), copr_id)
+                    ))
 
 
 class WhoosheeStamp(object):

frontend/coprs_frontend/tests/coprs_test_case.py

@@ -9,7 +9,7 @@
 import uuid
 
 import pytest
-from sqlalchemy import desc
+from sqlalchemy import desc, text
 import decorator
 
 import coprs
@@ -78,12 +78,15 @@ def setup_method(self, method):
     def teardown_method(self, method):
         # delete just data, not the tables
         self.db.session.rollback()
-        for tbl in reversed(self.db.metadata.sorted_tables):
-            self.db.engine.execute(tbl.delete())
 
-        # This table has after_create() hook with default data in models.py, so
-        # we actually need to drop it so the setup_method() re-creates the data
-        self.db.engine.execute('drop table dist_git_instance')
+        with self.db.engine.connect() as connection:
+            for tbl in reversed(self.db.metadata.sorted_tables):
+                connection.execute(tbl.delete())
+            # This table has after_create() hook with default data in models.py,
+            # so we actually need to drop it so the setup_method() re-creates
+            # the data
+            connection.execute(text('drop table dist_git_instance'))
+            connection.commit()
 
         self.app.config = self.original_config.copy()
         cache.clear()