I have three tables:
1) book: id (primary), name
2) shop: code (unique, not primary), name
3) book_shop: book_id, shop_id (code), price
I want to get shops in book like
book.getShop();
How to link this entities?
I tried:
#Data
#NoArgsConstructor
#Entity
#Table(name = "book", schema = "example")
#EntityListeners(AuditingEntityListener.class)
public class Book {
#Id
#GeneratedValue(strategy = GenerationType.IDENTITY)
private int id;
private String name;
#OneToMany(mappedBy = "book", cascade = CascadeType.ALL, orphanRemoval = true)
private Set<BookShop> bookShop;
}
.
#Data
#NoArgsConstructor
#Entity
#Table(name = "shop", schema = "example")
#EntityListeners(AuditingEntityListener.class)
public class Shop {
#Id
private int code;
private String name;
#OneToMany(mappedBy = "shop", cascade = CascadeType.ALL, orphanRemoval = true)
private Set<BookShop> bookShop;
}
.
#Data
#NoArgsConstructor
#Entity
#Table(name = "book_shop", schema = "example")
public class BookShop implements Serializable {
#Id
#GeneratedValue(strategy = GenerationType.IDENTITY)
private int id;
#Id
#ManyToOne
#JoinColumn(name = "book_id")
private Book book;
#Id
#ManyToOne
#JoinColumn(name = "shop_id")
private Shop shop;
#Column(name = "price")
private int fromDate;
}
This code return empty set: Book book = bookRepostiory.getById(1).get().getBookShop()
Try the many to many mapping implement like as below remove your book_shop table,
add this code to shop entity,
#ManyToMany(fetch = FetchType.EAGER, cascade = CascadeType.PERSIST)
#JoinTable(name = "book_shop",
joinColumns = {#JoinColumn(name = "book_id", nullable = false)},
inverseJoinColumns = {#JoinColumn(name = "shop_id", nullable = false)})
private Set<Book> bookList = null;
add this code to book entity,
#ManyToMany(fetch = FetchType.LAZY, cascade = CascadeType.ALL,
mappedBy ="bookList")
private Set<Shop> shopList=null;
if any issue inform!!
I would suggest, first - initialize the set in the entity
private Set<BookShop> bookShop = new HashSet<>();
Second, add fetch = FetchType.EAGER to your association, for e.g.
#OneToMany(fetch = FetchType.EAGER, mappedBy = "book", cascade = CascadeType.ALL)
Related
I`ve been trying to create a #ManyToMany relationship between two entities (team&contest) but when i try to post to the contest controller api i get a error 415 saying that
Failed to evaluate Jackson deserialization for type [[simple type, class com.project.Contest.Contest]]: com.fasterxml.jackson.databind.exc.InvalidDefinitionException: Cannot handle managed/back reference 'defaultReference': back reference type (`java.util.List<com.project.Contest.Contest>`) not compatible with managed type (com.project.Contest.Contest)
team :
#Getter
#Setter
#NoArgsConstructor
#AllArgsConstructor
#Entity
#Table(name = "team")
public class Team {
#Id
#GeneratedValue(strategy = GenerationType.AUTO)
private long id;
#JsonBackReference
//#JsonIdentityInfo(generator = ObjectIdGenerators.PropertyGenerator.class , property = "id")
#ManyToMany(mappedBy = "teams", cascade = CascadeType.PERSIST)
private List<Contest> contests;
private String name;
private int wins, losses;
}
contest :
#Getter
#Setter
#NoArgsConstructor
#AllArgsConstructor
#Entity
#Table(name = "contest")
public class Contest {
#Id
#GeneratedValue(strategy = GenerationType.AUTO)
private long id;
private String name;
#ManyToMany(cascade = CascadeType.PERSIST)
#JsonManagedReference
//#JsonIdentityInfo(generator = ObjectIdGenerators.PropertyGenerator.class , property = "id")
#JoinTable(
name = "team_contest",
inverseJoinColumns = #JoinColumn(name = "team_id"),
joinColumns = #JoinColumn( name = "contest_id")
)
private List<Team> teams;
#ManyToMany(cascade = CascadeType.PERSIST)
#JsonManagedReference
//#JsonIdentityInfo(generator = ObjectIdGenerators.PropertyGenerator.class , property = "id")
#JoinTable(
name = "contest_user",
joinColumns = #JoinColumn(name = "contest_id"),
inverseJoinColumns = #JoinColumn( name = "user_id")
)
private List<User> users;
}
i found out i can use #JsonIdentityInfo(generator = ObjectIdGenerators.PropertyGenerator.class , property = "id") instead of #JsonBackReference & #JsonManagedReference which helped me as it let me post to the database but then i refaced the problem that i can`t retrieve contest.teams[1] as because both objects have references to one another it creates some kind of an infinite loop as to get to the reference of the second object(contest.teams[1]) it needs to show the reference the contest.teams[0] has to the contest and soo forth. please help <3
This is the most famous bi-directional issue. To break up the loop while serialization, you can choose:
#JsonIgnore
#JsonIdentityInfo
JPA Projections
#EntityGraph
Or simply make the relationship uni-directional
thanks meridbt i was already using #JsonIdentityInfo but in the wrong place and i read a bit online and fixed my issue by doing this :
team :
#Getter
#Setter
#NoArgsConstructor
#AllArgsConstructor
#Entity
#Table(name = "team")
#JsonIdentityInfo(generator = ObjectIdGenerators.PropertyGenerator.class , property = "id")
public class Team {
#Id
#GeneratedValue(strategy = GenerationType.AUTO)
private long id;
#ManyToMany(mappedBy = "teams", cascade = CascadeType.PERSIST)
private List<Contest> contests;
private String name;
private int wins, losses;
}
contest :
#Getter
#Setter
#NoArgsConstructor
#AllArgsConstructor
#Entity
#Table(name = "contest")
#JsonIdentityInfo(generator = ObjectIdGenerators.PropertyGenerator.class, property = "id")
public class Contest {
#Id
#GeneratedValue(strategy = GenerationType.AUTO)
private long id;
private String name;
#ManyToMany(cascade = CascadeType.PERSIST)
#JoinTable(
name = "team_contest",
inverseJoinColumns = #JoinColumn(name = "team_id"),
joinColumns = #JoinColumn(name = "contest_id")
)
private List<Team> teams;
#ManyToMany(cascade = CascadeType.PERSIST)
#JoinTable(
name = "contest_user",
joinColumns = #JoinColumn(name = "contest_id"),
inverseJoinColumns = #JoinColumn(name = "user_id")
)
private List<User> users;
}
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.
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.
I have a project that is split between multiple modules, each module is imported into the main one as a maven dependency.
Persistence entities can be located at any of the projects but under the same package.
I have been trying to improve the startup time of the application by using the spring-context-indexer but it seems to cause an issue with detecting entities.
My #EntityScan is configured like this:
#EntityScan(basePackages = {"com.botscrew", "com.botscrew.demoadminpanel.entity.jpa","com.botscrew.admin.entity"})
The strange thing is that error looks like this
org.hibernate.AnnotationException: #OneToOne or #ManyToOne on com.botscrew.admin.entity.Bot.amioWhatsAppConfigs references an unknown entity: com.botscrew.admin.entity.services.configs.AmioWhatsAppConfigs
Essentially both entities are located under the same package but Bot entity was resolved but AmioWhatsAppConfigs was not.
The application starts perfectly fine without spring indexer.
I am using spring boot 2.2.1.RELEASE
Entities classes:
#Getter
#Setter
#Builder
#Entity
#ToString(of = {"id", "name"})
#AllArgsConstructor
#Table(name = "admin_bot")
#DiscriminatorValue("Bot")
#Inheritance(strategy = InheritanceType.SINGLE_TABLE)
public class Bot {
#Id
#GeneratedValue(strategy = GenerationType.IDENTITY)
private Integer id;
#Convert(converter = EmojiConverter.class)
private String name;
private Integer timezone;
private String greetingText;
#Column(columnDefinition = "tinyint(1) default 1")
private Boolean active;
#Column(unique = true, updatable = false, nullable = false)
private String publicIdentifier;
#OneToOne(fetch = FetchType.LAZY)
private PersistentMenuEntity persistentMenuEntity;
//TODO FetchType.LAZY
#OneToOne(fetch = FetchType.EAGER, cascade = CascadeType.ALL)
#JoinColumn(name = "widget_id")
private Widget widget;
//TODO FetchType.LAZY
#OneToOne(fetch = FetchType.EAGER, cascade = CascadeType.ALL)
private MessengerConfigs messengerConfigs;
//TODO FetchType.LAZY
#OneToOne(fetch = FetchType.EAGER, cascade = CascadeType.ALL)
private AmioWhatsAppConfigs amioWhatsAppConfigs;
#OneToOne(fetch = FetchType.EAGER, cascade = CascadeType.ALL)
private TwilioConfigs twilioConfigs;
#OneToOne(fetch = FetchType.EAGER, cascade = CascadeType.ALL)
private DialogflowConfigs dialogflowConfigs;
#OneToOne(fetch = FetchType.LAZY, cascade = CascadeType.ALL)
private ChatbaseConfig chatbaseConfig;
#OneToOne(fetch = FetchType.EAGER, cascade = CascadeType.ALL)
private SupportSettings supportSettings;
#OneToMany
private Set<Tag> tags;
#OneToMany(mappedBy = "bot")
private List<Broadcast> broadcasts;
#ManyToMany(fetch = FetchType.EAGER)
#JoinTable(name = "admin_bot_features",
joinColumns = {#JoinColumn(name = "bot_id")},
inverseJoinColumns = {#JoinColumn(name = "feature_id")})
private Set<Feature> features;
public Bot() {
this.active = true;
}
public Bot(String name, DefaultWidgetProperties defaultWidgetProperties) {
this.publicIdentifier = UUID.randomUUID().toString();
this.chatbaseConfig = new ChatbaseConfig();
this.amioWhatsAppConfigs = new AmioWhatsAppConfigs();
this.timezone = 0;
this.name = name;
this.active = true;
this.messengerConfigs = new MessengerConfigs();
this.dialogflowConfigs = new DialogflowConfigs();
this.widget = new Widget(defaultWidgetProperties);
this.supportSettings = new SupportSettings(false);
}
}
#Getter
#Setter
#Entity
#Accessors(chain = true)
#ToString
#Table(name = "admin_amio_whatsapp_configs")
public class AmioWhatsAppConfigs implements AmioWhatsAppBot {
#Id
#GeneratedValue(strategy = GenerationType.IDENTITY)
private Long id;
private String channelId;
private String accessToken;
private String secret;
}
Please help
I am editing my answer please check example
#EntityScan(basePackages = {"com.botscrew",
"com.botscrew.demoadminpanel.entity.jpa","com.botscrew.admin.entity.services.configs.*"})
I have a ManyToMany relationship that is broken down into 2 OneToMany relation. A Book can belong to multiple Categories and a Category can have many Books.
When I query for Book, the categories list just get empty. How can I get a list of all Categories that a Book belong to ? Am I missing something ?
#Entity
public class Book {
#Id
#GeneratedValue(strategy = GenerationType.AUTO)
private Integer id;
#NotBlank(message = "Please input book title")
private String title;
private Integer publishYear;
private String publisher;
private String language;
private Integer numberOfPages;
private String avatarUrl;
#OneToMany(targetEntity = BookCategory.class, cascade = CascadeType.ALL)
#JoinColumn(name = "category", nullable = false, insertable = false, updatable = false)
private Set<BookCategory> categories = new LinkedHashSet<>();
}
#Entity
public class Category {
#Id
#GeneratedValue(strategy = GenerationType.AUTO)
private Integer id;
#Column(nullable = false)
#NotBlank(message = "Please input category name")
private String name;
}
#Entity
public class BookCategory {
#Id
#GeneratedValue(strategy = GenerationType.AUTO)
private Integer id;
#ManyToOne
#JoinColumn(name = "book", nullable = false)
private Book book;
#ManyToOne
#JoinColumn(name = "category", nullable = false)
private Category category;
}
Try using mappedBy attribute with #OneTOMany annotation on the 'One' side of the OneToMany relation.
Or you can also try using the following:
#ManyToMany
#JoinTable(
name = “book”_category,
joinColumns = #JoinColumn(name = “book_id”),
inverseJoinColumns = #JoinColumn(name = “category_id))
Read more:
https://vladmihalcea.com/the-best-way-to-use-the-manytomany-annotation-with-jpa-and-hibernate/
I have a class called Tag:
#Entity
#Table(name = "tags")
public class Tag {
#Id
#GeneratedValue(strategy = GenerationType.IDENTITY)
private Long id;
private String name;
#ManyToMany(fetch = FetchType.LAZY,
cascade = {
CascadeType.PERSIST,
CascadeType.MERGE
},
mappedBy = "tags")
private Set<Post> posts = new HashSet<>();
...
}
And a class called Post
#Entity
#Table(name = "posts")
public class Post {
#Id
#GeneratedValue(strategy = GenerationType.IDENTITY)
private Long id;
#ManyToMany(fetch = FetchType.LAZY,
cascade = {
CascadeType.PERSIST,
CascadeType.MERGE
})
#JoinTable(name = "post_tags",
joinColumns = { #JoinColumn(name = "post_id") },
inverseJoinColumns = { #JoinColumn(name = "tag_id") })
private Set<Tag> tags = new HashSet<>();
...
}
It creates another table named post_tags.
How can I write a Controller to access that table as it is not similar a repository?
Is there more easy and convenient way to implement ManyToMany relationship ?
My pom.xml
You don't need to access that relation table manually. You can load load all Tag entities, and then load all the referenced Post entities.
The relation table is enterily managed by your ORM frameork.
But, if you still want to access the relation table, you can use native queries in your Spring Data JPA repository, e.g.
#Query(value="select post_id, tag_id from post_tags", nativeQuery=true)
List<PostTag> loadPostTags();
PostTag class is not a jpa-managed entity and must match the structue of the returned table:
public class PostTag {
private long postId;
private long tagId;
// getter, setter
}
Use this way
#Entity
#Table(name = "tags")
public class Tag {
#Id
#GeneratedValue(strategy = GenerationType.IDENTITY)
private Long id;
private String name;
#ManyToMany(cascade = CascadeType.ALL)
#JoinTable(name = "post_tags",
joinColumns = { #JoinColumn(name = "id") },
inverseJoinColumns = { #JoinColumn(name = "post_id") })
private Set<Post> posts = new HashSet<>();
...
}
#Entity
#Table(name = "posts")
public class Post {
#Id
#Column(name = "post_id")
#GeneratedValue(strategy = GenerationType.IDENTITY)
private Long postId;
...
}