Establish a relationship between actions and the agents targeted by them when actions are inserted into postgres

database/actions.go

@@ -202,6 +202,19 @@ func (db *DB) InsertAction(a mig.Action) (err error) {
 	if err != nil {
 		return fmt.Errorf("Failed to store action: '%v'", err)
 	}
+
+	// The following query establishes a relation between the new action and all
+	// agents targeted by the action.
+	_, err = db.c.Exec(fmt.Sprintf(`
+  insert into agent_action_relation (agent_id, action_id)
+  select $1, A.id
+  from agents A
+  where (%s);
+  `, a.Target), a.ID)
+	if err != nil {
+		return fmt.Errorf("Failed to establish relation between action and targeted agents: '%s'", err.Error())
+	}
+
 	return
 }