Spring data jpa specification and pageable in #manytomany using join table repository - spring-boot

Question

I have a use case to filter and paginate the record with #manytomany relation using a separate join table.
Below are the relation and entities
public class User {
private Long userId;
private String userName
#OneToMany(mappedBy = "user")
private List<UserRole> userRole;
}
public class Role {
private Long roleId;
private String roleName
#OneToMany(mappedBy = "role")
private List<UserRole> userRole;
}
public class UserRole{
private Long id;
private Integer active
#ManyToOne
#MapsId("userId")
private User user;
#ManyToOne
#MapsId("roleId")
private Role role;
}
#Repository
public interface UserRoleRepository extends
JpaRepository<UserRole, String>,
JpaSpecificationExecutor<UserRole> {
}
public class UserRoleSpecification implements Specification<UserRole>
{
private SearchCriteria criteria;
public RuleEntitySpecification(SearchCriteria criteria ) {
this.criteria = criteria;
}
#Override
public Predicate toPredicate(Root<UserRole> root,
CriteriaQuery<?> query,
CriteriaBuilder criteriaBuilder) {
if(criteria.getOperation().equalsIgnoreCase("eq")) {
if(root.get(criteria.getKey()).getJavaType() == String.class)
{
return criteriaBuilder.like(root.get(criteria.getKey()),
"%" + criteria.getValue() + "%");
} else {
return criteriaBuilder.equal(root.get(criteria.getKey()),
criteria.getValue());
}
}
return null;
}
}
public class SearchCriteria implements Serializable {
private String key;
private String operation;
private Object value;
}
UserRoleSpecificationBuilder specBuilder = new UserRoleSpecificationBuilder();
specBuilder.with("active", "eq" , 1); // giving us proper result
Specification<UserRole> spec = specBuilder.build();
Pageable paging = PageRequest.of(0, 5, Sort.by("user.userId"));
Page<UserRole> pagedResult = userRoleRepository.findAll(spec,paging);
But when we try to filter based on Rule/User table properties like userName/roleName specBuilder.with("user.userName", "eq" , "xyz");, I am getting following exception:
org.springframework.dao.InvalidDataAccessApiUsageException:
Unable to locate Attribute with the the given name
[user.userName] on this ManagedType
Kindly suggest if there is any way to achieve the filter using UserRole Join Table repository and specification
Pagination is also required hence using repository of Type UserRole JoinTable.

Answer 1

#Override
public Predicate toPredicate(Root<UserRole> root,
CriteriaQuery<?> query,
CriteriaBuilder criteriaBuilder) {
if (criteria.getOperation().equalsIgnoreCase("eq")) {
String key = criteria.getKey();
Path path;
if (key.contains(".")) {
String attributeName1 = key.split("\\.")[0];
String attributeName2 = key.split("\\.")[1];
path = root.get(attributeName1).get(attributeName2);
} else {
path = root.get(key);
}
if (path.getJavaType() == String.class) {
return criteriaBuilder.like(path, "%" + criteria.getValue() + "%");
} else {
return criteriaBuilder.equal(root.get(key), criteria.getValue());
}
}
return null;
}