[MISC] Add database field in the provider-side databag (#84)

* Update postgresql_provider.py

* fix lint / unit

* fix unittest

* wip

Author: deusebio

src/relations/postgresql_provider.py

@@ -92,6 +92,9 @@ def _on_database_requested(self, event: DatabaseRequestedEvent) -> None:
             self.database_provides.set_version(
                 event.relation.id, self.charm.postgresql.get_postgresql_version()
             )
+
+            # Set the database name
+            self.database_provides.set_database(event.relation.id, database)
         except (
             PostgreSQLCreateDatabaseError,
             PostgreSQLCreateUserError,

tests/unit/test_postgresql_provider.py

@@ -63,12 +63,7 @@ def request_database(self):
         self.harness.update_relation_data(
             self.rel_id,
             self.app,
-            {
-                "data": "",
-                "username": "",
-                "password": "",
-                "version": "",
-            },
+            {"data": "", "username": "", "password": "", "version": "", "database": ""},
         )
 
         # Simulate the request of a new database plus extra user roles.
@@ -140,6 +135,7 @@ def test_on_database_requested(
                     "username": user,
                     "password": "test-password",
                     "version": POSTGRESQL_VERSION,
+                    "database": f"{DATABASE}",
                 },
             )