jap使用时遇到failed to lazily initialize a collection of XXXX 问题

Could not write JSON: failed to lazily initialize a collection of role: com.blog.Entity.UserInfo.userRoles, could not initialize proxy - no Session; 
nested exception is com.fasterxml.jackson.databind.JsonMappingException: failed to lazily initialize a collection of role: com.blog.yongyu.signInStart.Entity.UserInfo.userRoles, could not initialize proxy - no Session (through reference chain: com.blog..Entity.BaseClass.DataResult[\"data\"]->java.util.ArrayList[0]->com.blog.Entity.UserInfo[\"role\"])",

postman发送请求时，报错信息如上。

原因在于：类User Info和Role使用OneToMany时，类UserInfo中用了懒加载fetch=FetchType.LAZY，导致在类UserInfo中取List<Role>时，加载数据的session已经关闭，出现报错。

解决方法：

1. 将懒加载替换成急加载fetch=FetchType.EAGER。不过，这样子违背了初始的想法，最好不要这样；
2. 修改配置文件application.properties，设置 spring.jpa.open-in-view=true。解释：Spring Boot中的spring.jpa.open-in-view = true属性是什么？

 

别人的答案：JPA中的failed to lazily initialize a collection of role:xxxx no session or session was closed异常分析与解决