I have a many to many User <-> Roles relation.
The User entity looks like this:
#Entity
#Table(name = "user",
uniqueConstraints = {#UniqueConstraint(columnNames = {"username", "email"})})
public class User {
#Id
#GeneratedValue(strategy = GenerationType.IDENTITY)
#Column(name = "id", unique = true, nullable = false)
private Long id;
#ManyToMany(cascade = CascadeType.ALL)
#JoinTable(name = "user_roles",
joinColumns = #JoinColumn(name = "user_id", referencedColumnName = "id"),
inverseJoinColumns = #JoinColumn(name = "role_id", referencedColumnName = "id"))
private Set<Role> roles = new HashSet<>();
}
And the Roles entity is the following:
#Entity
#Table(name = "role")
public class Role {
#Id
#GeneratedValue(strategy = GenerationType.AUTO)
#Column(name = "id", updatable = true, nullable = false)
private Long id;
#Enumerated(EnumType.STRING)
#Column(length = 60, name = "roleName", updatable = true, nullable = false)
private RoleName roleName;
}
Everything works fine, except one thing. When I insert two users with the same role the roles table getting two records with the same role, but different IDs.
The question is, can I eliminate this behavior? Ideally the ROLES table should not contain duplicated roles.
Any advice would be appreciated. :)
I cannot find a problem in your entity mapping. The problem should be in the business logic where you try to save the user entity.
The problem you have described can happen if you set a not-yet-saved Role entity to a User. In other terms, your Role do not have an id field yet.
You need to get the Role from your persistent provider and set it to User.
If you are using spring-data, it can be like:
User user = ....
Role role = rolesRepository.findByName(roleName);
user.setRole(role);
// The persist User
Related
Suppose you have two resources, User and Account. They are stored in separate tables but have a one-to-one relationship, and all API calls should work with them both together. For example a POST request to create a User with an Account would send this data:
{ "name" : "Joe Bloggs", "account" : { "title" : "My Account" }}
to /users rather than have multiple controllers with separate routes like users/1/account. This is because I need the User object to be just one, regardless of how it is stored internally.
Let's say I create these Entity classes
#Table(name = "user")
public class User {
#OneToOne(mappedBy = "user", cascade = CascadeType.ALL, orphanRemoval = true, fetch = FetchType.LAZY)
#NotNull
Account account;
#Column(name = "name")
String name;
}
#Table(name = "account")
public class Account {
#OneToOne(cascade = CascadeType.ALL, optional = false, fetch = FetchType.LAZY)
#JoinColumn(name = "user_id", nullable = false)
#NotNull
User user;
#Column(name = "title")
String title;
}
The problem is when I make that POST request above, it throws an error because user_id is missing, since that's required for the join, but I cannot send the user_id because the User has not yet been created.
Is there a way to create both entities in a single API call?
Since it is a bi-directional relation, and one-to-one is a mandatory in this case, you should persist a user entity and only then persist an account. And one more thing isn't clear here is db schema. What are the pk's of entities? I coukd offer to use user.id as a single identity for both of tables. If so, entities would be as:
User(id, name), Account(user_id, title) and its entities are:
#Table(name = "account")
#Entity
public class Account {
#Id
#Column(name = "user_id", insertable = false, updatable = false)
private Long id;
#OneToOne(mappedBy = "account", fetch = FetchType.LAZY, optional = false)
#MapsId
private User user;
#Column(name = "title")
private String title;
}
#Table(name = "user")
#Entity
public class User {
#Id
#GeneratedValue(strategy = GenerationType.AUTO)
private Long id;;
#OneToOne(cascade = CascadeType.ALL, orphanRemoval = true, fetch = FetchType.LAZY)
#JoinColumn(name = "id", referencedColumnName = "user_id")
private Account account;
#Column(name = "name")
private String name;
}
at the service layer you must save them consistently:
#Transactional
public void save(User userModel) {
Account account = user.getAccount();
user.setAccount(null);
userRepository.save(user);
account.setUser(user);
accountRepository.save(account);
}
it will be done within a single transaction. But you must save the user first, coz the user_id is a PK of the account table. #MapsId shows that user's id is used as an account's identity
Another case is when account's id is stored in the user table:
User(id, name, account_id), Account(id, title) and entities are:
#Table(name = "account")
#Entity
public class Account {
#Id
#Column(name = "id")
#GeneratedValue(strategy = GenerationType.AUTO)
private Long id;
#OneToOne(cascade = CascadeType.ALL, mappedBy = "account")
private User user;
#Column(name = "title")
private String title;
}
#Table(name = "user")
#Entity
public class User {
#Id
#GeneratedValue(strategy = GenerationType.AUTO)
private Long id;
#Column(name = "account_id", insertable = false, updatable = false)
private Long accountId;
#OneToOne(cascade = CascadeType.ALL, orphanRemoval = true, fetch = FetchType.LAZY)
#JoinColumn(name = "account_id", referencedColumnName = "id", unique = true)
private Account account;
#Column(name = "name")
private String name;
}
in this case an Account entity will be implisitly persisted while User entity saving:
#Transactional
public void save(User userModel) {
userRepository.save(user);
}
will cause an insertion into the both of tables. Since cascade and orphane are declared, for deletion would be enough to set null for the account reference:
user.setAccount(null);
userRepository.save(user);
I currently have a problem with this Relationship, I have tried everything I saw on the internet. Still, I get this error: ERROR: column roles0_.user_id does not exist.
I have a boot app that has spring security, and I need to login using users from PostgreSQL database.
But I just can't get the relation between the user and the Role to work.
Here are Entity classes:
#Data
#Entity
#Table(name="user",schema = "public")
public class User {
#Id
#GeneratedValue(strategy = GenerationType.IDENTITY)
#Column(name = "user_id")
private Integer id;
#Column(unique = true)
private String username;
private String password;
private boolean enabled;
#OneToMany(mappedBy = "user", fetch = FetchType.EAGER)
private List<Role> roles;
}
#Data
#Entity
#Table(name="role",schema = "public")
public class Role {
#Id
#Column(name="role_id")
#GeneratedValue(strategy = GenerationType.IDENTITY)
private Integer id;
private String name;
#ManyToOne()
#JoinColumn(name ="user_id")
private User user;
}
The database looks fine, I looked at the column names, etc. I don't know what to do to get rid of this error. I have the user table, and another table named roles, which include id and name, 2 inputs, USER and ADMIN...
It seems that the #JoinColumn annotation requires one additional column in the roles table the one with #ManytoOne relation, because when I add the column the error disappears, but when I'm trying to get the role from each user, I get an empty List. The foreign key is set as well, from the roles column to the role_id column from role table.
worked for me this way:
#Entity
#Data
#Table(name = "users")
public class User{
#ManyToMany(fetch = FetchType.EAGER)
#JoinTable(name = "user_roles", joinColumns = {#JoinColumn(name = "user_id", referencedColumnName = "id")},
inverseJoinColumns = {#JoinColumn(name = "role_id", referencedColumnName = "id")})
private List<Role> roles;
}
and then in roles just:
#Entity
#Table(name = "roles")
public class Role{
#ManyToMany(mappedBy = "roles", fetch = LAZY)
private List<User> users;
}
that's if you are ok with third table user_roles (user_id, role_id) which manages the many to many relation
User table :
#OneToMany(cascade = CascadeType.ALL, mappedBy = "user", fetch = FetchType.EAGER)
private List<Role> roles;
Role table :
#ManyToOne(fetch = FetchType.LAZY)
#JoinColumn(name = "user_id")
private User user;
I am a newbie to the Spring boot (but worked in Laravel). I am facing a problem of cyclic redundancy in #ManyToMany relation. Let's go through the scenario -
What response I ma getting (fetching user's list which has many to many relationships with roles) -
Following is the ER-diagram of associated tables to manage many to many relationship between users and roles table.
User entity class has following code -
#Entity
#Where(clause = "deleted_at IS NULL")
#SQLDelete(sql = "UPDATE users SET deleted_at = CURRENT_TIMESTAMP WHERE id = ?", check = ResultCheckStyle.COUNT)
#Getter
#Setter
#NoArgsConstructor
#AllArgsConstructor
#Table(name = "users")
#JsonIgnoreProperties(
value = {"createdAt", "updatedAt", "deletedAt"}
)
public class User {
#Id
#Column(name = "id", updatable = false, nullable = false)
#GeneratedValue(strategy = GenerationType.IDENTITY)
private long id;
#Column(name = "name", nullable = false)
#NotBlank(message = "Name field can not be empty")
private String name;
.....
.....
.....
#ManyToMany(targetEntity = Role.class, fetch = FetchType.EAGER)
#JoinTable(name = "user_roles",joinColumns = #JoinColumn(name = "user_id"),
inverseJoinColumns = #JoinColumn(name = "role_id"))
private Set<Role> roles;
}
And Role entity is as follows -
#Entity
#Table(name = "roles")
#Getter
#Setter
#NoArgsConstructor
#AllArgsConstructor
#SQLDelete(sql = "UPDATE roles SET deleted_at = CURRENT_TIMESTAMP WHERE id = ?", check = ResultCheckStyle.COUNT)
#Where(clause = "deleted_at IS NULL")
#JsonIgnoreProperties(
value = {"createdAt", "updatedAt", "deletedAt"}
)
public class Role {
#Id
#GeneratedValue(strategy = GenerationType.IDENTITY)
#Column(name = "id", updatable = false, nullable = false)
private long id;
#Column(name = "title")
#NotBlank(message = "Title field must be not null")
private String title;
......
......
......
#OneToMany(targetEntity = User.class, fetch = FetchType.EAGER)
#JoinTable(name = "user_roles",joinColumns = #JoinColumn(name = "role_id"),
inverseJoinColumns = #JoinColumn(name = "user_id"))
private List<User> users;
}
How to solve this problem? What I am doing wrong here?
Since you are fetching the list directly. You will have to mention the annotation #JsonIgnore everywhere you have mapping specified. By everywhere I don't mean literally everywhere. Just use the annotation and see how it works.
Edit -> Just do it in roles table where you have mapped it to the user table. It will then skip the user mapping while fetching the data.
#JsonIgnore
private List<User> users;
You could annotate users within Role with #JsonBackReference.
Easiest would probably be to annotate the List<T>'s with a #JsonIgnoreProperties annotation to break the cyclic dependencies.
#JsonIgnoreProperties("users")
private List<Role> roles;
#JsonIgnoreProperties("roles")
private List<User> users;
I'm looking for a way to implement (0..n) many to many relation in JPA, much possibly using #ManyToMany annotation. All examples that I found were about (1..n) relations. What I need to accomplish:
- I've got two entities: Contact and Tag. Each Contact can have 0..n Tags. Each Tag can have 0..n Contacts. From SQL point of view it would look like
this: Contact (0..n) --- (1) Contact_has_Tag (1) --- (0..n) Tag.
Code below is not working for me because JPA is linking columns with INNER JOIN.
OFC I could do this using intermediate entity and #OneToMany and #ManyToOne annotations, but I want a simpler sollution.
#Data
#Entity
public class Contact {
#Id
#GeneratedValue(strategy = GenerationType.IDENTITY)
#JsonIgnore
private long id;
#Column(unique = true)
private String email;
// ...
#ManyToMany(fetch = FetchType.LAZY, cascade = CascadeType.ALL)
#JsonIgnore
#JoinTable(
name = "contact_has_tag",
joinColumns = #JoinColumn(name = "contact_id", referencedColumnName = "id", updatable = false, nullable = true),
inverseJoinColumns = #JoinColumn(name = "tag_id", referencedColumnName = "id", updatable = false, nullable = true))
private List<ContactTag> contactTags = new ArrayList<ContactTag>();
}
#Entity
#Data
public class ContactTag {
#Id
#GeneratedValue(strategy = GenerationType.IDENTITY)
private int id;
#Column
private String name;
#ManyToMany(mappedBy="contactTags", fetch = FetchType.LAZY)
#JsonIgnore
private List<Contact> contacts = new ArrayList<Contact>();
}
Any ideas how it should be done?
There is a unidirectional ManyToMany mapping between Role and Privilege with Role as the owning entity like so
Role
#Entity
public class Role extends BaseEntity {
#Id
#GeneratedValue(strategy = GenerationType.IDENTITY)
#Basic(optional = false)
#Column(name = "role_id")
private Integer roleId;
#Size(max = 45)
#Column(name = "role")
private String role;
#JoinTable(name = "role_privilege", joinColumns = {
#JoinColumn(name = "role_role_id", referencedColumnName = "role_id")}, inverseJoinColumns = {
#JoinColumn(name = "privilege_privilege_id", referencedColumnName = "privilege_id")})
#ManyToMany(
cascade = {
CascadeType.DETACH,
CascadeType.MERGE,
CascadeType.REFRESH,
CascadeType.PERSIST }, fetch = FetchType.EAGER, targetEntity = Privilege.class)
private Collection<Privilege> privilegeCollection;
#Transient
private Collection<Privilege> parentPrivilegeCollection;
#OneToMany(cascade = CascadeType.ALL, mappedBy = "roleId")
#JsonIgnore
private Collection<User> userCollection;
public Role() {
}
//getters,setter,hashcode,equals removed for brevity
}
Privilege
#Entity
public class Privilege extends BaseEntity {
#Id
#GeneratedValue(strategy = GenerationType.IDENTITY)
#Basic(optional = false)
#Column(name = "privilege_id")
private Integer privilegeId;
#Size(max = 45)
#Column(name = "name")
private String name;
#Size(max = 150)
#Column(name = "description")
private String description;
#Size(max = 45)
#Column(name = "friendly_name")
private String friendlyName;
#JoinTable(name = "privilege_hierachy", joinColumns = {
#JoinColumn(name = "parent_privilege", referencedColumnName = "privilege_id")}, inverseJoinColumns = {
#JoinColumn(name = "child_privilege", referencedColumnName = "privilege_id")})
#ManyToMany
private Collection<Privilege> privilegeCollection;
public Privilege() {
}
}
The Problem
Whenever i set updated list of privileges in a role and update, the join table is successfully updated without removing either target or owning entity, and that is desired result. The problem is on update it also affect another self join table in Privilege called privilege_hierachy which is not what is expect.
Is it possible for hibernate to only update the Role-Privilege mant-to-many relationship and let other relation unchanged.
Spring Data Jpa is used for data persistence
It sounds like you are updating the privileges by (removing old privileges and) adding new ones. If you do that, clearly, the second join table (the self-referencing table) could be updated with new rows, based on what you are passing.
I see that for the self-referencing table, Privilege, you are not setting cascade type. It defaults to no operation, and that sounds like what you want. But my guess is based on what you said "Whenever i set updated list of privileges in a role", and that tells me you are creating new privileges for a role, instead of using existing privileges and associate them with the role.