feat(pg_dump): Add '--if-exists' option for pg_dump (and add tests)

dbbackup/db/postgresql.py

@@ -112,6 +112,7 @@ class PgDumpBinaryConnector(PgDumpConnector):
     restore_cmd = "pg_restore"
     single_transaction = True
     drop = True
+    if_exists = False
 
     def _create_dump(self):
         cmd = f"{self.dump_cmd} "
@@ -141,6 +142,9 @@ def _restore_dump(self, dump):
         if self.schemas:
             cmd += " -n " + " -n ".join(self.schemas)
 
+        if self.if_exists:
+            cmd += " --if-exists"
+
         cmd = f"{self.restore_prefix} {cmd} {self.restore_suffix}"
         stdout, stderr = self.run_command(cmd, stdin=dump, env=self.restore_env)
         return stdout, stderr

dbbackup/tests/test_connectors/test_postgresql.py

@@ -212,6 +212,17 @@ def test_create_dump_drop(self, mock_dump_cmd):
         self.connector.create_dump()
         self.assertNotIn(" --clean", mock_dump_cmd.call_args[0][0])
 
+    def test_create_dump_if_exists(self, mock_dump_cmd, mock_restore_cmd):
+        dump = self.connector.create_dump()
+        # Without
+        self.connector.if_exists = False
+        self.connector.restore_dump(dump)
+        self.assertNotIn(" --if-exists", mock_restore_cmd.call_args[0][0])
+        # With
+        self.connector.if_exists = True
+        self.connector.restore_dump(dump)
+        self.assertIn(" --if-exists", mock_restore_cmd.call_args[0][0])
+
     @patch(
         "dbbackup.db.postgresql.PgDumpBinaryConnector.run_command",
         return_value=(BytesIO(), BytesIO()),

docs/changelog.rst

@@ -4,7 +4,7 @@ Changelog
 Unreleased
 ----------
 
-* Nothing (yet)!
+* Add option `--if-exists` for pg_dump command
 
 4.2.1 (2024-08-23)
 ----------

docs/databases.rst

@@ -166,6 +166,13 @@ This corresponds to ``--clean`` argument of ``pg_dump`` and ``pg_restore``.
 
 Default: ``True``
 
+IF_EXISTS
+~~~~
+
+Use DROP ... IF EXISTS commands to drop objects in ``--clean`` mode of ``pg_dump``.
+
+Default: ``False``
+
 PostGIS
 -------