I have multiple back-reference classes in a class. Since I use #JsonBackReference for them, I get an error. I assigned #JsonIdentityInfo annotation for those classes, but I still get the same error.
public class X implements Serializable {
....
//bi-directional many-to-one association to Booking
#ManyToOne(fetch = FetchType.EAGER)
#JoinColumn(name = "xxA", nullable = false)
#JsonBackReference
private A a;
//bi-directional many-to-one association to Client
#ManyToOne(fetch = FetchType.EAGER)
#JoinColumn(name = "xxB", nullable = false)
#JsonBackReference
private B b;
...getters setters
}
#JsonIdentityInfo(generator = ObjectIdGenerators.IntSequenceGenerator.class, property = "#id")
public class B implements Serializable {
........
//bi-directional many-to-one association to BookedClient
#OneToMany(mappedBy = "b", fetch = FetchType.EAGER, cascade = CascadeType.ALL)
#JsonManagedReference
private List < X > xxB;
........ getters setters
}
#JsonIdentityInfo(generator = ObjectIdGenerators.IntSequenceGenerator.class, property = "#id")
public class A implements Serializable {
........
//bi-directional many-to-one association to BookedClient
#OneToMany(mappedBy = "a", fetch = FetchType.EAGER, cascade = CascadeType.ALL)
#JsonManagedReference
private List < X > xxA;
........ getters setters
}
error:
com.fasterxml.jackson.databind.JsonMappingException: Multiple back-reference properties with name 'defaultReference'
How can I resolve this error? Can I not use multiple back-reference in a class?
According to Jackson's javadoc, both #JsonManagedReference and #JsonBackReference accept a name value that binds them together:
#JsonBackReference("a")
private A a;
#JsonManagedReference("a")
private List < X > xxA;
I also faced this issue, but in the last I resolved it.
//This is parent class
#Entity
#Table(name = "checklist")
#JsonIgnoreProperties("inspection")
public class Checklist implements java.io.Serializable {
#ManyToOne
#JoinColumn(name = "product_id", referencedColumnName = "id")
#JsonBackReference
private Product product;
#OneToMany(mappedBy = "checklists", cascade = CascadeType.ALL)
#JsonManagedReference
private Set<Inspection> inspection = new HashSet<Inspection>();
//Constructor
//Getter and Setter
}
//This is child class
#Entity
#Table(name = "inspections")
public class Inspection {
#ManyToOne
#JoinColumn(name = "chk_id", referencedColumnName = "id")
private Checklist checklists;
//Constructor
//Getter and Setter
}
By mentioning #JsonIgnoreProperties("inspection") and #JsonManagedReference in Parent class
Resolved the issue raised by using two #JSONBackRefrence in same parent class.
So this did actually take me a while...
You can annotate your referencse accordingly using #JsonIdentityReference(alwaysAsId = true) and then leave it off the master reference
#JsonIdentityReference(alwaysAsId = true)
private Set<PackInstructionGroup> groups = new TreeSet<>();
Related
I am working on a springboot application. I have 2 entity classes, Group and User. I also have #ManyToMany relationship defined in the Group class (Owning entity), and also in the User class, so that I can fetch all the groups a user belongs to. Unfortunately, I can't create a new group or a new user due to the following error;
{
"timestamp": "2022-09-09T20:29:22.606+00:00",
"status": 415,
"error": "Unsupported Media Type",
"message": "Content type 'application/json;charset=UTF-8' not supported"
}
When I try to fetch all groups a user belongs to by calling user.get().getGroups(); I get a a stack overflow error
Note: Currently I have #JsonManagedReference and #JsonBackReference in Group and User classes respectively. I also tried adding #JsonIdentityInfo(generator = ObjectIdGenerators.PropertyGenerator.class, property = "id") on both classes, but this did not work either. Adding value parameter to #JsonManagedReference and #JsonBackReference as demonstrated below did not work either. What am I doing wrong? What am I missing?
This is my Group entity class
#Table(name = "`group`") // <- group is a reserved keyword in SQL
public class Group {
#Id
#GeneratedValue(strategy = GenerationType.AUTO)
private Long id;
#JsonView(Views.Public.class)
private String name;
private Integer maximumMembers;
#ManyToMany(fetch = FetchType.LAZY, cascade = {CascadeType.ALL})
#JoinTable(name = "group_user", joinColumns = #JoinColumn(name = "group_id"), inverseJoinColumns = #JoinColumn(name = "user_id"))
#JsonView(Views.Public.class)
#JsonManagedReference(value = "group-member")
private Set<User> groupMembers;
}
This is my User entity class
public class User {
#Id
#GeneratedValue(strategy = GenerationType.AUTO)
#JsonView(Views.Public.class)
private Long id;
#JsonView(Views.Public.class)
private String nickname;
#JsonView(Views.Public.class)
private String username; // <- Unique user's phone number
private String password;
#ElementCollection(targetClass = ApplicationUserRole.class)
#CollectionTable(name = "user_role", joinColumns = #JoinColumn(name = "user_id"))
#Enumerated(EnumType.STRING)
#Column(name = "role")
private Set<ApplicationUserRole> roles;
#ManyToMany(mappedBy = "groupMembers", fetch = FetchType.LAZY, targetEntity = Group.class)
#JsonBackReference(value = "user-group")
private Set<Group> groups;
}
Minimal, Reproducible Example https://github.com/Java-Techie-jt/JPA-ManyToMany
I found a permanent solution for this problem. For anyone else facing a similar problem, This is what I found. First, my entity classes had #Data Lombok annotation. I removed this because the #Data annotation has a tendency of almost always loading collections even if you have FetchType.LAZY.
You can read more about why you should't annotate your entity class with #Data here https://www.jpa-buddy.com/blog/lombok-and-jpa-what-may-go-wrong/
After removing this annotation, I removed #JsonManagedReference and #JsonBackReference from both sides of the relationship(both entities). I then added #Jsonignore to the referencing side only(User class). This solves 2 things
Creating a group with a list of users works fine
Adding a list of users to a group works fine.
After this, we are left with one last problem. When we try to read a user from the api, we get a user without the associated list of groups they belong to, because we have #JsonIgnore on the user list. To solve this, I made the controller return a new object. So after fetching the user from my service, I map it to a new data transfer object, the I return this object in the controller.
From here I used #JsonView to filter my responses.
This is how my classes look, notice there is no #Data in annotations.
Group
#Builder
#Entity
#NoArgsConstructor
#AllArgsConstructor
#ToString
#Getter
#Setter
#Table(name = "`group`") // <- group is a reserved keyword in SQL
public class Group {
#Id
#GeneratedValue(strategy = GenerationType.AUTO)
private Long id;
private String name;
private Integer maximumMembers;
#ManyToMany(fetch = FetchType.EAGER,
cascade = {CascadeType.MERGE, CascadeType.MERGE, CascadeType.PERSIST, CascadeType.REFRESH})
#JoinTable(name = "group_user",
joinColumns = #JoinColumn(name = "group_id"),
inverseJoinColumns = #JoinColumn(name = "user_id"))
#JsonView(UserViews.PublicUserDetails.class)
private Set<User> groupMembers = new HashSet<>();
}
User
#Builder
#Entity
#NoArgsConstructor
#AllArgsConstructor
#ToString
#Getter
#Setter
public class User {
#Id
#GeneratedValue(strategy = GenerationType.AUTO)
#JsonView(UserViews.PublicUserDetails.class)
private Long id;
#JsonView(UserViews.PublicUserDetails.class)
private String nickname;
#JsonView(UserViews.PublicUserDetails.class)
private String username; // <- Unique user's phone number
private String password;
#ElementCollection(targetClass = ApplicationUserRole.class)
#CollectionTable(name = "user_role", joinColumns = #JoinColumn(name = "user_id"))
#Enumerated(EnumType.STRING)
#Column(name = "role")
#JsonView(UserViews.PublicUserDetails.class)
private Set<ApplicationUserRole> roles;
#JsonIgnore
#ManyToMany(mappedBy = "groupMembers", fetch = FetchType.LAZY, targetEntity = Group.class)
private Set<Group> groups = new HashSet<>();
}
Method fetching user in user controller
#GetMapping("/get-groups")
public ResponseEntity<UserRequestResponseDTO> getWithGroups(#RequestParam(name = "userId") Long userId) {
User user = userService.getWithGroups(userId);
UserRequestResponseDTO response = UserRequestResponseDTO.builder()
.nickname(user.getNickname())
.username(user.getUsername())
.groups(user.getGroups())
.build();
return ResponseEntity.ok().body(response);
}
Hopefully this helps someone💁
I want to build entity classes for the following relationship. I want an entity ProductWiseCustomer which has a composite key. Those key also mapped with Product and Customer entities. How to achieve the purpose?
So far what I have done.
Product.java
#Entity
#Table(name = "product")
public class Product {
#Id
private Long productId;
private String productName;
private Decimal productPrice;
#OneToMany(cascade = CascadeType.ALL, fetch = FetchType.EAGER, targetEntity = CustomerProductCompound.class)
private Set<CustomerProductCompound> customerProductCompound;
//Constructor
//Setter-getter
}
Customer.java
#Entity
#Table(name = "customerinfo")
public class CustomerInfo {
#Id
private Long customerId;
private String customerName;
private Boolean isActive;
#OneToMany(cascade = CascadeType.ALL, fetch = FetchType.EAGER, targetEntity = CustomerProductCompound.class)
private Set<CustomerProductCompound> customerProductCompound;
//Constructor
//Setter-getter
}
CustomerProductCompound.java
#Embeddable
public class CustomerProductCompound
{
#ManyToOne
#JoinColumn(name = "customerId")
private CustomerInfo customerInfo;
#ManyToOne
#JoinColumn(name = "productId")
private Product product;
//Constructor
//Setter-getter
}
While running the application getting the following error:
Use of #OneToMany or #ManyToMany targeting an unmapped class: com.auth.model.CustomerInfo.customerProductCompound[com.auth.model.CustomerProductCompound].
One solution is to use a composite identifier with #EmbeddableId.
#Entity
public class ProductWiseCustomer {
#EmbeddedId
private ProductCustomerKey key;
}
#Embeddable
public class ProductCustomerKey {
#ManyToOne(fetch = FetchType.LAZY)
private Customer customer;
#ManyToOne(fetch = FetchType.LAZY)
private Product product;
}
Please see the hibernate documentation:
https://docs.jboss.org/hibernate/orm/5.2/userguide/html_single/Hibernate_User_Guide.html#identifiers-composite-aggregated
CustomerProductCompound as you have defined just the primary key of ProductWiseCustomer. Your collections inside CustomerInfo and Product must contain ProductWiseCustomer items, not its key.
#Entity
#Table(name = "product")
public class Product {
#Id
private Long productId;
private String productName;
private Decimal productPrice;
#OneToMany(mappedBy = "product", cascade = CascadeType.ALL, fetch = FetchType.EAGER, orphanRemoval = true)
private Set<ProductWiseCustomer> productWiseCustomers;
}
#Entity
#Table(name = "customerinfo")
public class CustomerInfo {
#Id
private Long customerId;
private String customerName;
private Boolean isActive;
#OneToMany(mappedBy = "customer", cascade = CascadeType.ALL, fetch = FetchType.EAGER, orphanRemoval = true)
private Set<ProductWiseCustomer> productWiseCustomers;
}
Notice I added the mappedBy property in the annotations. It needs to point to the property name on the other side that refers to this object. The JPA name, not the SQL name. targetEntity is rarely necessary, and I've suggested orphanRemoval, so that if you remove one from the set, you don't have to manually delete it for it to go away.
As for the ProductWiseCustomer, you do need the same key as shown by Modular Coder
#Embeddable
public class ProductCustomerKey {
#ManyToOne(fetch = FetchType.LAZY)
#JoinColumn(name = "customerId)
private Customer customer;
#ManyToOne(fetch = FetchType.LAZY)
#JoinColumn(name = "productId")
private Product product;
}
But I recommend you use #IdClass instead of #EmbeddedId
#Entity
#IdClass(ProductCustomerKey.class)
public class ProductWiseCustomer {
#ManyToOne(fetch = FetchType.LAZY) // should be lazy here
#JoinColumn(name = "customerId)
private Customer customer;
#ManyToOne(fetch = FetchType.LAZY) // should be lazy here
#JoinColumn(name = "productId")
private Product product;
private OffsetDateTime createDate;
private String remarks;
// getters, setters
}
I'm having problems mapping composite keys in jpa / hibernate. The parent entity and the child entity both have composite primary keys.
I have been able to use #mapsId when the parent entity has a simple key and the child has a composite key.
In the hibernate documentation they use #JoinCoumns in the mapping to demonstrate mapping two composite keys. But in their example its not clear where those column references are defined.
I have the following:
#Embeddable
public class PriceRequestLegKey implements Serializable {
#Column(name = "leg_request_id")
private String requestId;
#Column(name = "display_index")
private int displayIndex;
...
}
#Embeddable
public class AllocationKey implements Serializable {
#Column(name = "leg_request_id")
private String requestId;
#Column(name = "display_index")
private int displayIndex;
#Column(name = "allocation_index")
private int allocationIndex;
...
}
#Entity(name = "PriceRequestLeg")
public class PriceRequestLegModel {
#EmbeddedId
private PriceRequestLegKey legKey;
#OneToMany(cascade = CascadeType.ALL)
#JoinColumns({
#JoinColumn(name = "leg_request_id", referencedColumnName = "leg_request_id"),
#JoinColumn(name = "display_index", referencedColumnName = "display_index")
})
private List<AllocationModel> allocations;
...
}
#Entity(name = "Allocation")
public class AllocationModel {
#EmbeddedId
private AllocationKey allocationKey;
#ManyToOne
#MapsId
#JoinColumns({
#JoinColumn(name = "leg_request_id", referencedColumnName = "leg_request_id"),
#JoinColumn(name = "display_index", referencedColumnName = "display_index")
})
private PriceRequestLegModel leg;
...
}
At runtime when saving it gives the follow exception:
org.springframework.orm.jpa.JpaSystemException: could not get a field value by reflection getter of com.lbg.legato.rfq.data.entity.AllocationKey.displayIndex; nested exception is org.hibernate.PropertyAccessException: could not get a field value by reflection getter of com.lbg.legato.rfq.data.entity.AllocationKey.displayIndex
Which I assume is spurious as there are getters and setters. I also get the same error if I use mappedBy="leg" on the priceRequestLegModel and #MapsId on the AllocationModel. Could anyone point out what I'm doing wrong here?
You should restore the mappedBy="leg" to the PriceRequestLegModel #OneToMany annotation:
#Entity(name = "PriceRequestLeg")
public class PriceRequestLegModel {
#EmbeddedId
private PriceRequestLegKey legKey;
#OneToMany(mappedBy="leg", cascade = CascadeType.ALL)
private List<AllocationModel> allocations;
...
}
Then you should change AllocationKey to reference PriceRequestLegKey:
#Embeddable
public class AllocationKey implements Serializable {
PriceRequestLegKey legKey; // corresponds to PK type of PriceRequestLegModel
#Column(name = "allocation_index")
private int allocationIndex;
...
}
And then set the value of the Allocation.leg #MapsId annotation appropriately:
#Entity(name = "Allocation")
public class AllocationModel {
#EmbeddedId
private AllocationKey allocationKey;
#ManyToOne
#MapsId("legKey")
#JoinColumns({
#JoinColumn(name = "leg_request_id", referencedColumnName = "leg_request_id"),
#JoinColumn(name = "display_index", referencedColumnName = "display_index")
})
private PriceRequestLegModel leg;
...
}
Some examples like this are in the JPA 2.2 spec section 2.4.1.
I have an Invoice entity which contains another entity - Counterparty and a list of another entities - Items. While setting up relations between list of items and invoice, there were no problems. However, when I try to set up a similar relation between invoice entity and counterparty entity, I get an error:
#OneToOne or #ManyToOne on pl.coderstrust.model.Invoice.counterparty references an unknown entity: pl.coderstrust.model.counterparty.Counterparty
This is my invoice, which expects to contain only one counterparty and a list of items.
#Entity
#Table(name = "invoices")
public class Invoice implements Comparable<Invoice>, Serializable {
#Id
#GeneratedValue(strategy = GenerationType.IDENTITY)
#Column(name = "invoice_id")
private int id;
#Column(name = "date")
private LocalDate date = LocalDate.now();
#ManyToOne(cascade = {CascadeType.DETACH, CascadeType.MERGE, CascadeType.PERSIST,
CascadeType.REFRESH})
#JoinColumn(name = "nip")
private Counterparty counterparty;
#OneToMany(mappedBy = "invoice", cascade = {CascadeType.PERSIST, CascadeType.MERGE,
CascadeType.DETACH, CascadeType.REFRESH})
#JsonBackReference
private List<InvoiceItem> invoiceItems = new ArrayList<>();
This is my item entity, which can be related to one invoice:
#Id
#GeneratedValue(strategy = GenerationType.IDENTITY)
#Column(name = "item_id")
private int id;
private String description;
private int numberOfItems;
private BigDecimal amount;
private BigDecimal vatAmount;
#JoinColumn(name = "vat_code")
#Enumerated(EnumType.ORDINAL)
private Vat vat;
#OneToOne(mappedBy = "invoice_id", fetch = FetchType.EAGER, cascade = {CascadeType.DETACH,
CascadeType.MERGE, CascadeType.PERSIST,
CascadeType.REFRESH})
#JsonManagedReference
private Invoice invoice;
This is my counterparty, which is supposed to be related to many invoices:
#Entity
#Table(name = "counterparties")
public class Counterparty implements Serializable {
#Id
#Column(name = "nip")
private String nip;
private String companyName;
private String phoneNumber;
private String bankName;
private String bankNumber;
#OneToOne(fetch = FetchType.LAZY, mappedBy = "counterparty", cascade = CascadeType.ALL)
private Address address;
#OneToMany(mappedBy = "counterparty", fetch = FetchType.LAZY, cascade = {CascadeType.PERSIST,
CascadeType.MERGE,
CascadeType.DETACH, CascadeType.REFRESH})
private List<Invoice> invoices;
What is wrong with invoice-counterparty relations?
That Hibernate error is usually thrown when the class is not added to the hibernate configuration. Hibernate needs to be told all of the classes that serve as entities before it can use them.
How do you make your classes known to Hibernate? I.e. either by adding the class to the Configuration object:
configuration.addClass(Counterparty.class);
or by adding the class into a package that is scanned for entities when you are using Spring?
On another note: there seems to be something odd with the Item class perhaps? It specifies a OneToOne relation to Invoice; should this not be a ManyToOne (meaning that a single invoice can have 0 or more Items)?
Here is my JPA structure:
Movie (look at cascade types):
#Entity
#Table(name = "movie")
public class Movie {
#Id
#Column(name = "movie_id")
#GeneratedValue(strategy = GenerationType.AUTO)
private Integer id;
//#OneToMany(cascade = CascadeType.ALL, mappedBy = "primaryKey.movie") //stack overflow
#OneToMany(mappedBy = "primaryKey.movie") //works fine
private List<Rating> ratings;
....
}
Rating:
#Entity
#Table(name = "rating")
#AssociationOverrides({#AssociationOverride(name = "primaryKey.movie", joinColumns = #JoinColumn(name = "movie_id")),
#AssociationOverride(name = "primaryKey.user", joinColumns = #JoinColumn(name = "imdb_user_id"))})
public class Rating {
#EmbeddedId
private RatingId primaryKey = new RatingId();
#Column(name = "rating_value")
private Integer ratingValue;
.....
}
RatingId:
#Embeddable
public class RatingId implements Serializable{
#ManyToOne
private Movie movie;
#ManyToOne
private User user;
}
When I call entityManager.merge(Movie movie) with CascadeType.ALL I get the StackOverflowError. If remove cascading, merge call doesn't throw the error. Where may be a problem?
I think this problem related to composite primary key. There is no error when merge performed on another entities with the same one-to-many relationship, but without composite id.
StackOverflow was caused by cyclic relations. To avoid exception I marked keys in many-to-many table as #ManyToOne(fetch = FetchType.LAZY).
That's how my tables look after modifications: https://stackoverflow.com/a/32544519/2089491