Thymeleaf access object in outerloop from innerloop - spring-boot

Question

i am looping through a list of "roles" , inside each one i loop through a list of "notifications" ( a role can have many notifications )
<div class="row justify-content-center">
<div class="col-sm-3" th:each="role : ${roles}">
<div class="card">
<div class="card-body">
<h5 class="card-title" th:text="${role.name}"></h5>
Notifications :
<div class="input-group mb-3">
<th:block th:each="notif : ${notif_list}">
<div class="custom-control custom-control-inline">
<input type="checkbox" class="custom-control-input"
th:id="${notif.id_notif_type}"
th:value="${notif.id_notif_type}" th:field="${role.notifs}">
<label class="custom-control-label" th:text="${notif.type}"
th:for="${notif.id_notif_type}"></label>
</div>
</th:block>
</div>
</div>
</div>
</div>
</div>
i want access an object "role" inside the notification loop by using th:field="${role.notifs}
here is my Role class :
#Entity
#Table(name = "roles")
#Transactional
public class Role implements Serializable{
public Role() {
}
public Role(Integer id, String name) {
super();
this.id = id;
this.name = name;
}
#Id
#Column(name = "role_id")
#GeneratedValue(strategy = GenerationType.IDENTITY)
private Integer id;
private String name;
#ManyToMany(cascade = CascadeType.MERGE, fetch = FetchType.EAGER)
#JoinTable(name = "roles_notifs", joinColumns = #JoinColumn(name = "role_id"), inverseJoinColumns = #JoinColumn(name = "notif_id"))
private Set<NotifType> notifs = new HashSet<>();
public Integer getId() {
return id;
}
public void setId(Integer id) {
this.id = id;
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public Set<NotifType> getNotifs() {
return notifs;
}
public void setNotifs(Set<NotifType> notifs) {
this.notifs = notifs;
}
public void addNotif(NotifType notif) {
notifs.add(notif);
}
public void removeNotif(NotifType notif) {
notifs.remove(notif);
}
#Override
public String toString() {
return name;
}
#Override
public int hashCode() {
final int prime = 31;
int result = 1;
result = prime * result + ((id == null) ? 0 : id.hashCode());
return result;
}
#Override
public boolean equals(Object obj) {
if (this == obj)
return true;
if (obj == null)
return false;
if (getClass() != obj.getClass())
return false;
Role other = (Role) obj;
if (id == null) {
if (other.id != null)
return false;
} else if (!id.equals(other.id))
return false;
return true;
}
i got an error on ${role.notifs} , so how can i access the outer object "role" from the inner loop.
i got this error Neither BindingResult nor plain target object for bean name 'role' available as request attribute