Infinite JSON in ManyToMany relationship mapped by Intermediary Table - spring-boot

Question

I have 2 entities that relate to one another. These 2 entities should map to each other in a Many-To-Many relationship, however, I need to also have a timestamp of their respective relationship (when it happened), so I am trying to map them using an intermediary table.
Initially, the relationship was One-To-Many, but I realized that I actually need a Many-To-Many as the business logic requires this. The structure is still the same, as in there is a Parent-Child relationship, but this time, a child should have multiple parents as well.
My BaseEntity is an abstract class that contains the fields present in all the other entities:
#Data
#MappedSuperclass
public abstract class BaseEntity {
#Id
#Min(100)
#Max(Integer.MAX_VALUE)
#GeneratedValue(strategy = GenerationType.IDENTITY)
protected Long id;
#CreationTimestamp
#Column(name = "Created_At", updatable = false)
protected ZonedDateTime createdDate;
#UpdateTimestamp
#Column(name = "Updated_At")
protected ZonedDateTime updatedDate;
#NotNull
#Column(name = "Is_Active")
protected Boolean active = true;
}
Then I have my 2 entities that should relate in a Many-To-Many style. This is my first entity and should be the parent:
#Data
#Entity
#NoArgsConstructor
#AllArgsConstructor
#Table(name = "User")
#EqualsAndHashCode(callSuper = true)
#TypeDefs( {
#TypeDef(name = "json", typeClass = JsonStringType.class),
#TypeDef(name = "jsonb", typeClass = JsonBinaryType.class)
})
public class UserEntity extends BaseEntity {
#NotBlank
#Column(name = "User_Name", columnDefinition = "varchar(255) default 'N/A'")
private String userName;
#Nullable
#JoinColumn(name = "User_Id")
#OneToMany(cascade = CascadeType.ALL, fetch = FetchType.LAZY)
private List<UserRole> roleList = new ArrayList<>();
}
My second entity is considered the child entity:
#Data
#Entity
#NoArgsConstructor
#AllArgsConstructor
#Table(name = "Role")
#Where(clause = "is_active = true")
#EqualsAndHashCode(callSuper = true)
public class RoleEntity extends BaseEntity {
#NotBlank
#Column(name = "Name")
private String name;
#JsonIgnore
#JoinColumn(name = "Role_Id")
#OneToMany(cascade = CascadeType.ALL, fetch = FetchType.LAZY)
private List<UserRole> userList = new ArrayList<>();
}
I also have my intermediary entity:
#Data
#Entity
#Getter
#NoArgsConstructor
#AllArgsConstructor
#Where(clause = "is_active = true")
#EqualsAndHashCode(callSuper = true)
#Table(name = "User_Role", uniqueConstraints= #UniqueConstraint(columnNames={"User_Id", "Role_Id"}))
public class UserRole extends BaseEntity {
// Adding #JsonIgnore here will only cause an error
#JoinColumn(name = "User_Id")
#ManyToOne(cascade = CascadeType.ALL, fetch = FetchType.LAZY, optional = false, targetEntity = UserEntity.class)
private UserEntity user;
#JoinColumn(name = "Role_Id")
#ManyToOne(cascade = CascadeType.ALL, fetch = FetchType.LAZY, optional = false, targetEntity = RoleEntity.class)
private RoleEntity role;
}
Problem now is that when I try to get my UserEntity, I get infinite recursion.
So far I've tried using #JsonIgnore, #JsonManagedReference, #JsonBackReference and it did not work or I simply don't know where or how to use them properly.
Recap:
2 entities mapped by Many-To-Many relationship;
Many-To-Many implemented using an intermediary entity and One-To-Many + Many-To-One associations;
Getting recursion when showing my UserEntity;
Update: I managed to get this fixed using a different approach described in my answer to this question.

Answer 1

I fixed this by implementing a Composite Key structure and just using the #JsonIgnore annotation:
#Getter
#Setter
#Embeddable
#EqualsAndHashCode
#NoArgsConstructor
#AllArgsConstructor
public class UserRoleKey implements Serializable {
#Column(name = "User_Id")
Long userId;
#Column(name = "Role_Id")
Long roleId;
}
This gets to be used in the intermediary entity, which now doesn't use my BaseEntity anymore.
#Data
#Entity
#NoArgsConstructor
#AllArgsConstructor
#Table(name = "User_Role", uniqueConstraints= #UniqueConstraint(columnNames={"User_Id", "Role_Id"}))
public class UserRole {
#JsonIgnore
#EmbeddedId
private UserRoleKey id;
#JsonIgnore
#MapsId("userId")
#JoinColumn(name = "User_Id")
#ManyToOne(optional = false, targetEntity = UserEntity.class)
private UserEntity user;
#MapsId("roleId")
#JoinColumn(name = "Role_Id")
#ManyToOne(optional = false, targetEntity = RoleEntity.class)
private RoleEntity role;
#CreationTimestamp
#Column(name = "Created_At", updatable = false)
private ZonedDateTime createdDate;
}
Now, for my two entities, I have this definition:
UserEntity class (definition of the role):
#Nullable
#OneToMany(cascade = CascadeType.ALL, fetch = FetchType.LAZY, mappedBy = "user", orphanRemoval = true)
private List<UserRole> roleList = new ArrayList<>();
RoleEntity class (definition of the user)
#Nullable
#JsonIgnore
#OneToMany(cascade = CascadeType.ALL, fetch = FetchType.LAZY, mappedBy = "role", orphanRemoval = true)
private List<UserRole> userList = new ArrayList<>();
This seems to be working and no longer returns an infinite JSON recursion.