'Many To One' attribute type should not be a container

Issue

I have this class:

import org.springframework.security.core.userdetails.UserDetails;

@Entity
@Table(name="t_user")
@JsonInclude(JsonInclude.Include.NON_NULL)
@JsonIgnoreProperties(ignoreUnknown = true)
@Data
public class User implements Serializable, UserDetails {

@Override
    public Collection<? extends GrantedAuthority> getAuthorities() {
        return null;
    }
..
}

but I have this compilation error:

'Many To One' attribute type should not be a container 

Solution

@ManyToOne should annotate a field not a collection. For collection fields the right annotation is @OneToMany.

So if you have

@ManyToOne
private List<Something> list;

that should be

@OneToMany
private List<Something> list;

Answered By – Panagiotis Bougioukos

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