java - Spring Data JPA、Hibernate、@ManyToOne(fetch=FetchType.LAZY) 和 org.hibernate.LazyInitializationException : could not initialize proxy - no Session

Question

在Employee and Phone example

如何使 Hibernate Lazy 初始化工作(在 Spring Boot 中)？

org.hibernate.LazyInitializationException: could not initialize proxy - no Session
    at org.hibernate.proxy.AbstractLazyInitializer.initialize(AbstractLazyInitializer.java:165) ~[hibernate-core-4.3.11.Final.jar:4.3.11.Final]
    at org.hibernate.proxy.AbstractLazyInitializer.getImplementation(AbstractLazyInitializer.java:286) ~[hibernate-core-4.3.11.Final.jar:4.3.11.Final]
    at org.hibernate.proxy.pojo.javassist.JavassistLazyInitializer.invoke(JavassistLazyInitializer.java:185) ~[hibernate-core-4.3.11.Final.jar:4.3.11.Final]
    at com.example.domain.Employee_$$_jvstb7e_2.toString(Employee_$$_jvstb7e_2.java) ~[bin/:na]
    at java.lang.String.valueOf(String.java:2994) ~[na:1.8.0_74]
    at java.lang.StringBuilder.append(StringBuilder.java:131) ~[na:1.8.0_74]
    at com.example.domain.Phone.toString(Phone.java:13) ~[bin/:na]
    at com.example.SpringBootQuerydslTestBean$1.run(SpringBootQuerydslTestBean.java:49) ~[bin/:na]
    at org.springframework.boot.SpringApplication.callRunner(SpringApplication.java:806) [spring-boot-1.3.5.RELEASE.jar:1.3.5.RELEASE]
    ... 6 common frames omitted

Java code

public class Phone {
    ...
    @ManyToOne(fetch=FetchType.LAZY)
    private Employee owner;

附言有些人建议使用 FetchType.EAGER，如 org.hibernate.LazyInitializationException: could not initialize proxy - no Session ,但是让延迟加载工作(在 Spring Boot、Spring Data JPA 中)正是我的目标。

Answer 1

感谢 M. Deinum 的提示。

这个特殊情况通过在 Employee 中添加 toString() 来重新定义 Lombok toString()

来解决

@Override
    public String toString() {
        return "Employee [id=" + id + ", firstName=" + firstName + ", lastName=" + lastName + "]";
    }

还有specifying exactly Fetch type

代码在 https://github.com/paulvi/spring-boot-querydsl