当使用JPA CriteriaQuery和连接时，Spring Data REST抛出错误

Question

当通过JPA/Hibernate使用Spring Data REST并通过REST公开弹簧JpaRepository时，我收到JPA Criteria查询的错误。这是一个Spring Boot应用程序。

夫妇相关实体：

@Entity 
public class Appointment { 
... 
... 
@ManyToOne(fetch=FetchType.EAGER) 
@JoinColumn(name="doctor_id", insertable=false, updatable=false) 
private Doctor doctor; 
... 
... 
} 

@Entity 
public class Doctor { 
... 
... 
@Column(name = "doctor_name") 
private String doctorName = ""; 
... 
... 
} 

试图返回预约匹配的医生名字的名单，我建为JPA规范如下：

public Specification<Appointment> getSpecification() { 
    return new Specification<Appointment>() { 

     Join<Appointment, Doctor> doctorJoin; 

     @Override 
     public Predicate toPredicate(Root<Appointment> root, 
       CriteriaQuery<?> query, 
       CriteriaBuilder cb) { 
      Predicate p = cb.conjunction(); 
      ... //other critieria 
      p = addDoctorCriteria(p, cb, root, Doctor_.doctorName, getDoctorName()); 

      return p; 
     } 


     private Predicate addDoctorCriteria(Predicate p, 
       CriteriaBuilder cb, Root<Appointment> root, SingularAttribute<Doctor, String> property, String value) { 

      value = value + '%'; 

      if (doctorJoin == null) { 
       doctorJoin = root.join(Appointment_.doctor); 
      } 

      p = cb.and(p, cb.like(cb.lower(doctorJoin.<String>get(property)), value)); 

      return p; 
     } 
    }; 
} 

这引发以下异常：

org.hibernate.hql.internal.ast.QuerySyntaxException: 
Invalid path: 'generatedAlias1.doctorName' 
[select count(generatedAlias0) from my.package.Appointment as generatedAlias0 
where (1=1) and (lower(generatedAlias1.doctorName) like :param0)]; 

看起来像加入查询是不正确的 - 没有'generat from子句中的edAlias1'。似乎在Spring试图获得行数来构建分页信息时发生。其他依赖于约会属性（即没有加入）的标准很好。

我在做JPA连接是否正确？有关如何纠正此错误的任何建议？

Answer 1

这是我如何得到这个工作，如果有人遇到这样的问题：

Root<Doctor> doctor = query.from(Doctor.class); 
Predicate j1 = cb.equal(root.get(Appointment_.doctor), doctor); 
Predicate c1 = cb.like(cb.lower(doctor.<String>get(Doctor_.doctorName)), getDoctorName() + '%'); 
p = cb.and(p, cb.and(j1, c1));