When the connection url does not have an explicit driver, default to the provider driver

pygeoapi/provider/sql.py

@@ -71,6 +71,7 @@
 from sqlalchemy.orm import Session, load_only
 from sqlalchemy.sql.expression import and_
 from sqlalchemy.schema import Table
+from sqlalchemy.engine import make_url
 
 from pygeoapi.crs import get_transform_from_spec, get_srid
 from pygeoapi.provider.base import (
@@ -679,6 +680,11 @@ def get_engine(
             port=int(port),
             database=database
         )
+    else:
+        url = make_url(conn_str)
+        if url.drivername == url.get_backend_name():
+            url = url.set(drivername=driver_name)
+        conn_str = url
 
     # Separate connection-pool tuning from DBAPI connect args. Pool keys are
     # applied to create_engine() directly; everything left in connect_args is

tests/provider/test_postgresql_provider.py

@@ -1010,3 +1010,11 @@ def test_provider_count_false_with_resulttype_hits(config):
 
     # Assert
     assert results['numberMatched'] == 14776
+
+
+def test_get_engine_use_provider_driver():
+    engine = postgresql_provider_module.get_engine(
+        'postgresql+psycopg2', 'host', '5432', 'db', 'user', 'password',
+        'postgresql://user:password@host:5432/db'
+    )
+    assert engine.dialect.driver == 'psycopg2'