Registering relation-changed, preventing to be stuck in 'waiting' if …

…secrets weren't there at 'start' (#15)

src/charm.py

@@ -81,6 +81,9 @@ def __init__(self, *args):
         self.framework.observe(
             getattr(self.database.on, "endpoints_changed"), self._on_endpoints_changed
         )
+        self.framework.observe(
+            self.on[DATABASE_RELATION].relation_changed, self._on_relation_changed
+        )
         self.framework.observe(
             self.on[DATABASE_RELATION].relation_broken, self._on_relation_broken
         )
@@ -329,6 +332,13 @@ def _on_peer_relation_changed(self, _) -> None:
 
             self.unit.status = ActiveStatus()
 
+    def _on_relation_changed(self, _) -> None:
+        """Handle the database relation broken event."""
+        if self._database_config:
+            self.unit.status = ActiveStatus()
+        else:
+            self.unit.status = WaitingStatus()
+
     def _on_relation_broken(self, _) -> None:
         """Handle the database relation broken event."""
         self._stop_continuous_writes()