fix: build correct model

Author: Gu1nness

lib/charms/data_platform_libs/v1/data_interfaces.py

@@ -2505,22 +2505,22 @@ def _is_pg_plugin_enabled(plugin: str, connection_string: str) -> bool:
             )
             return False
 
-    def is_postgresql_plugin_enabled(self, plugin: str, relation_id: int = 0) -> bool:
+    def is_postgresql_plugin_enabled(self, plugin: str, relation_index: int = 0) -> bool:
         """Returns whether a plugin is enabled in the database.
 
         Args:
             plugin: name of the plugin to check.
-            relation_id: Optional index to check the database (default: 0 - first relation).
+            relation_index: Optional index to check the database (default: 0 - first relation).
         """
         if not psycopg2:
             return False
 
         # Can't check a non existing relation.
-        if len(self.relations) <= relation_id:
+        if len(self.relations) <= relation_index:
             return False
 
-        relation_id = self.relations[relation_id].id
-        model = self.interface.build_model(relation_id=relation_id)
+        relation = self.relations[relation_index]
+        model = self.interface.build_model(relation_id=relation.id, component=relation.app)
         for request in model.requests:
             if request.endpoints and request.username and request.password:
                 host = request.endpoints.split(":")[0]