feat: [RepositorioRecurso]: Creada una función para obtener la media de estrellas

src/main/java/com/ujaen/tfg/mangaffinity/repositorios/RepositorioRecurso.java

@@ -116,4 +116,15 @@ public class RepositorioRecurso {
                 .getResultList();
     }
 
+    @Transactional(readOnly = true)
+    public Double calcularMediaEstrellasPorRecurso(Long recursoId) {
+        Double media = em.createQuery(
+                        "SELECT AVG(r.estrellas) FROM Resena r WHERE r.recurso.id = :recursoId",
+                        Double.class)
+                .setParameter("recursoId", recursoId)
+                .getSingleResult();
+
+        return media != null ? media : 0.0;
+    }
+
 }
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