[FIXED] Spring Boot Non Unique Result Exception

Issue

Hello everyone I am using SpringBoot with Mysql . I have this error when i try to show information

I have below code in my controller :

query did not return a unique result: 2; nested exception is javax.persistence.NonUniqueResultException: query did not return a unique result: 2
org.springframework.dao.IncorrectResultSizeDataAccessException: query did not return a unique result: 2; nested exception is javax.persistence.NonUniqueResultException: query did not return a unique result: 2

Code

 @GetMapping("showdeveforma/{id}")
 public String ShowDeveFormation(Model m , @PathVariable Long id)

 { 
     Formation frm = frmreop.findById(id).get();

     m.addAttribute("avis", srv.findByforma(frm));

     return"ChefProjetAffichageAffectationDeveForma";
 }

Solution

Your DAO method returns more than one row but you have a single value as the result type defined and not a Collection.

Answered By - Simon Martinelli