jap使用時遇到failed to lazily initialize a collection of XXXX 問題

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發送請求時，報錯信息如上。

原因在於：類User Info和Role使用OneToMany時，類UserInfo中用了懶加載fetch=FetchType.LAZY，導致在類UserInfo中取List<Role>時，加載數據的session已經關閉，出現報錯。

解決方法：

1. 將懶加載替換成急加載fetch=FetchType.EAGER。不過，這樣子違背了初始的想法，最好不要這樣；
2. 修改配置文件application.properties，設置 spring.jpa.open-in-view=true。解釋：Spring Boot中的spring.jpa.open-in-view = true屬性是什么？

 

別人的答案：JPA中的failed to lazily initialize a collection of role:xxxx no session or session was closed異常分析與解決