Fix: Use empty event for unsupported dialects (#421)

Author: adrien-berchet

geoalchemy2/__init__.py

@@ -7,6 +7,7 @@
 
 from geoalchemy2 import functions  # noqa
 from geoalchemy2 import types  # noqa
+from geoalchemy2.dialects import common
 from geoalchemy2.dialects import postgresql
 from geoalchemy2.dialects import sqlite
 from geoalchemy2.dialects.common import _check_spatial_type
@@ -27,12 +28,7 @@ def _select_dialect(dialect_name):
         "postgresql": postgresql,
         "sqlite": sqlite,
     }
-    try:
-        return known_dialects[dialect_name]
-    except KeyError:
-        raise ValueError(
-            f"The dialect '{dialect_name}' is unknown, please choose one of {known_dialects.keys()}"
-        )
+    return known_dialects.get(dialect_name, common)
 
 
 def _setup_ddl_event_listeners():

tests/test_functional.py

@@ -32,6 +32,7 @@
 from sqlalchemy.testing.assertions import ComparesTables
 
 import geoalchemy2
+import geoalchemy2.dialects
 from geoalchemy2 import Geography
 from geoalchemy2 import Geometry
 from geoalchemy2 import Raster
@@ -92,6 +93,39 @@ def test_no_geom_type(self, conn):
             # Drop the table
             t.drop(bind=conn)
 
+    @test_only_with_dialects("postgresql")
+    def test_common_dialect(self, conn, monkeypatch, metadata, Lake):
+        monkeypatch.setattr(conn.dialect, "name", "UNKNOWN DIALECT")
+
+        marks = []
+
+        def before_create(table, bind, **kw):
+            marks.append("before_create")
+            return
+
+        def after_create(table, bind, **kw):
+            marks.append("after_create")
+            return
+
+        def before_drop(table, bind, **kw):
+            marks.append("before_drop")
+            return
+
+        def after_drop(table, bind, **kw):
+            marks.append("after_drop")
+            return
+
+        monkeypatch.setattr(geoalchemy2.dialects.common, "before_create", value=before_create)
+        monkeypatch.setattr(geoalchemy2.dialects.common, "after_create", value=after_create)
+        monkeypatch.setattr(geoalchemy2.dialects.common, "before_drop", value=before_drop)
+        monkeypatch.setattr(geoalchemy2.dialects.common, "after_drop", value=after_drop)
+
+        metadata.drop_all(conn, checkfirst=True)
+        metadata.create_all(conn)
+        metadata.drop_all(conn, checkfirst=True)
+
+        assert marks == ["before_create", "after_create", "before_drop", "after_drop"]
+
 
 class TestMiscellaneous:
     @test_only_with_dialects("sqlite")