fix: fix to reload table when checking if table exists (#1002)

* fix: fix to reload table

* changes

* lint

Author: asthamohta

google/cloud/spanner_v1/table.py

@@ -77,6 +77,11 @@ def _exists(self, snapshot):
         :rtype: bool
         :returns: True if the table exists, else false.
         """
+        if (
+            self._database.database_dialect
+            == DatabaseDialect.DATABASE_DIALECT_UNSPECIFIED
+        ):
+            self._database.reload()
         if self._database.database_dialect == DatabaseDialect.POSTGRESQL:
             results = snapshot.execute_sql(
                 _EXISTS_TEMPLATE.format("WHERE TABLE_NAME = $1"),

tests/system/test_table_api.py

@@ -29,6 +29,16 @@ def test_table_exists_not_found(shared_database):
     assert not table.exists()
 
 
+def test_table_exists_reload_database_dialect(
+    shared_instance, shared_database, not_emulator
+):
+    database = shared_instance.database(shared_database.database_id)
+    assert database.database_dialect == DatabaseDialect.DATABASE_DIALECT_UNSPECIFIED
+    table = database.table("all_types")
+    assert table.exists()
+    assert database.database_dialect != DatabaseDialect.DATABASE_DIALECT_UNSPECIFIED
+
+
 def test_db_list_tables(shared_database):
     tables = shared_database.list_tables()
     table_ids = set(table.table_id for table in tables)