java - How to post list of users in Spring -

i have domain class in spring:

@entity @table(name="like") public class {  @id @generatedvalue(strategy = generationtype.identity) long id;  @manytoone(cascade= cascadetype.merge, targetentity = user.class) @joincolumn(name = "user_id") @ondelete(action= ondeleteaction.cascade) set<user> user;  @onetomany(mappedby = "like", orphanremoval = true ,cascade= cascadetype.all, targetentity = picture.class) @ondelete(action= ondeleteaction.cascade) set<picture> pictures;  public like() { }  public like(set<user> user) {     this.user = user; }  public long getid() {     return id; }  public void setid(long id) {     this.id = id; } @jsonignore public set<user> getuser() {     return user; } @jsonignore public void setuser(set<user> user) {     this.user = user; }  @jsonignore public set<picture> getpictures() {     return pictures; } @jsonignore public void setpictures(set<picture> pictures) {     this.pictures = pictures; } } } 

and have table in sql script

create table if not exists `like` ( `id` int not null primary key auto_increment, `user_id` bigint, foreign key (user_id) references `user`(id) )engine=innodb default charset=utf8; 

and problem when send post request in postman:

java.lang.illegalargumentexception: can not set java.lang.long field com.nyters.webapp.domain.user.id java.util.hashset

controllerlike.java

  @restcontroller   @requestmapping("api/like")   public class likecontroller {    private likeservice likeservice;    @autowired   public likecontroller(likeservice likeservice){   this.likeservice = likeservice;  }     @requestmapping(path = "/{id}", method = requestmethod.get)     public responseentity<likedto> findone(@pathvariable long id) {    likedto picturedto = likeservice.findone(id);     if (picturedto != null) {     return new responseentity<>(picturedto, httpstatus.ok);   } else {     return new responseentity<>(httpstatus.not_found);   }   }  @requestmapping(method = requestmethod.get) public responseentity<list<likedto>> findall() { list<likedto> likedtos = likeservice.findall();  if (likedtos != null) {     return new responseentity<>(likedtos, httpstatus.ok); } else {     return new responseentity<>(httpstatus.not_found); } }   @requestmapping(method = requestmethod.post)  public responseentity<likedto> save(@requestbody string likedtostring)   throws   ioexception {   likedto likedto = new objectmapper().readvalue(likedtostring,    likedto.class);   likedto saved = likeservice.save(likedto);  if (saved != null) {     return new responseentity<>(saved, httpstatus.ok); } else {     return new responseentity<>(httpstatus.not_found); } } 

i guess prob mapping

like.java

@fetch(value = fetchmode.select) @onetomany(cascade = cascadetype.all) @joincolumn(name = "user_id") @jsonignore private list<user> userlist; //based on user_id u can fetch userlist db 

user.java

@id @generatedvalue(strategy = generationtype.auto) @column(name = "user_id") private long user_id;