I use hibernate and spring-data. There are two tables with many-to-many relationship.
#Entity
#Table(name = "FirstEntity")
public class FirstEntity {
#Id
#GeneratedValue(strategy = GenerationType.AUTO)
#Column(name = "first_entity_id")
private Long id;
#Column(name = "first_entiry_name")
private String name;
/* getters and setters are below*/
}
#Entity
#Table(name = "SecondEntity")
public class SecondEntity {
#Id
#GeneratedValue(strategy = GenerationType.AUTO)
#Column(name = "second_entity_id")
private Long id;
#Column(name = "second_entiry_name")
private String name;
#Column(name = "second_entiry_desc")
private String description;
/* getters and setters are below*/
}
And entity for cross-reference table.
#Entity
#Table(name = "FirstSecondEntity")
public class FirstSecondEntity {
#Id
#GeneratedValue(strategy = GenerationType.AUTO)
#Column(name = "first_second_entity_id")
private Long id;
#Column(name = "first_entity_id")
private Long firstEntityId;
#Column(name = "second_entity_id")
private Long secondEntityId;
/* getters and setters are below*/
}
I need SELECT like this
SELECT FirstEntity.name, SecondEntity.name, SecondEntity.description FROM SecondEntity INNER JOIN FirstSecondEntity ON SecondEntity.id = FirstSecondEntity.secondEntityId INNER JOIN User ON FirstEntity.id = FirstSecondEntity.firstEntityId
i.e. I need all records from cross-reference table where instead of ids there is actual info from entities.
Inserting this query into #Query annotation in my CrudRepository-extended class doesn't work because of
ERROR [main][org.hibernate.hql.internal.ast.ErrorCounter] Path expected for join!
So I need your help.
Your join table is all screwed up. In this case, you actually don't even need the join table as a hibernate mapping:
In Second Entity add the following list:
#ManyToMany(fetch = FetchType.LAZY)
#JoinTable(name = "FirstSecondEntity",
joinColumns = {
#JoinColumn(name = "first_entity_id",
nullable = false,
updatable = false) },
inverseJoinColumns = {
#JoinColumn(name = "second_entity_id",
nullable = false,
updatable = false) },
)
private List<FirstEntity> firstEntities;
In FirstEntity add the following list:
#ManyToMany(fetch = FetchType.LAZY,
mappedBy = "firstEntities")
private List<SecondEntity> secondEntities;
Related
I have two entities, each one pointing to one single table in an postgres. The entities belong to an Spring/graddle/JPA/Hibernate web application.
#Entity
#Table(name = "STAFF")
#AttributeOverride(name = "id", column = #Column(name = "ID"))
public class StaffEntity extends AbstractEntity {
#Column(name = "NAME")
private String name;
#Column(name = "SHORT_NAME")
private String shortName;
#ManyToOne(cascade = CascadeType.ALL, fetch = FetchType.LAZY)
#JoinColumn(name = "STAFF_GROUP_ID", referencedColumnName = "ID")
private StaffGroupEntity staffGroup;
/* More attributes, getters and setters */
#Entity
#Table(name = "STAFF_GROUP")
#AttributeOverride(name = "id", column = #Column(name = "ID"))
public class StaffGroupEntity extends AbstractEntity {
#Column(name = "NAME")
private String name;
#ManyToOne(cascade = CascadeType.ALL, fetch = FetchType.LAZY)
#JoinColumn(name = "LEAD_ID", referencedColumnName = "ID")
private StaffEntity lead;
/* More attributes, getters and setters */
When i update with swagger the group with a lead that is already in the group i get a stackOverFlowError
java.lang.StackOverflowError: null
mapping with mapstruct
I have 3 tables as #Entity, and 2 join tables in my spring + hibernate app.
In one of join table i have extra column. I want to take info from this info column when i take info from my main table.
Main table code:
#Entity
#Table(name = "items")
public class Items {
#Id
#GeneratedValue(strategy = GenerationType.IDENTITY)
#Column(name = "id")
private int id;
#Column(name = "name")
private String name;
#ManyToMany(fetch = FetchType.EAGER)
#JoinTable(name = "crafts"
,joinColumns = #JoinColumn(name = "item_id")
,inverseJoinColumns = #JoinColumn(name = "plot_id"))
private Set<Plots> plotInfo = new HashSet<>();
#ManyToMany(fetch = FetchType.EAGER)
#JoinTable(name = "item_materials"
,joinColumns = #JoinColumn(name = "item_id")
,inverseJoinColumns = #JoinColumn(name = "material_id"))
private Set<Materials> materialsInfo = new HashSet<>();
Table item_materials have this columns "id, item_id(fkey), material_id(fkey), expense" and one of this which names as "expense" i need to have in my final result.
How can i code my class to have "expense" in my result?
I read about #embeddable but still dont understand how to use in my project.
Don't use a #ManyToMany association. Map the join table as entity and model it similar to this:
#Entity
#Table(name = "items")
public class Items {
#OneToMany(mappedBy = "item")
private Set<Crafts> plotInfo = new HashSet<>();
}
#Entity
#Table(name = "plots")
public class Plots {
#OneToMany(mappedBy = "plot")
private Set<Crafts> items = new HashSet<>();
}
#Entity
#Table(name = "crafts")
public class Crafts {
#EmbeddedId
private CraftsId id;
#ManyToOne
#JoinColumn(name = "item_id", insertable = false, updatable = false)
private Items item;
#ManyToOne
#JoinColumn(name = "plot_id", insertable = false, updatable = false)
private Plots plot;
}
#Embeddable
public class CraftsId {
#Column(name = "item_id")
private Integer itemId;
#Column(name = "plot_id")
private Integer plotId;
// equals + hashCode
}
Consider the following database structure
I need to implement unidirectional one to one mapping like that (structure is simplified):
#Entity
#Table(name = "entity")
public class Customer {
#Id
#GeneratedValue(strategy = GenerationType.IDENTITY)
#Column(name = "id")
private Long id;
#OneToOne
#JoinColumn(name = "customer_info", nullable = false)
private CustomerInfo customerInfo;
#OneToOne
#JoinColumn(name = "customer_credentials", nullable = false)
private CustomerCredentials customerCredentials;
// getter, setters etc
}
#Entity
#Table(name = "customer_info")
public class CustomerInfo {
#Id
#GeneratedValue(strategy = GenerationType.IDENTITY)
#Column(name = "id")
private Long id;
// getter, setters etc
}
#Entity
#Table(name = "customer_credentials")
public class CustomerCredentials {
#Id
#GeneratedValue(strategy = GenerationType.IDENTITY)
#Column(name = "id")
private Long id;
// getter, setters etc
}
But somehow hibernate unable to differentiate that those joins are from different tables and throws such error:
Caused by: org.hibernate.MappingException: Repeated column in mapping for entity: com.example.Customer column: customer_id (should be mapped with insert="false" update="false")
Important notice: I do not want to use #OneToOne(mappedBy = "customer") because I need cascade save functionality
You can use #JoinTable instead of #JoinColumn to solve your problem:
#Entity #Table(name = "entity") public class Customer {
#Id
#GeneratedValue(strategy = GenerationType.IDENTITY)
#Column(name = "id")
private Long id;
#OneToOne(cascade = CascadeType.ALL, targetEntity = CustomerInfo.class)
#JoinTable(name = "customer_info", inverseJoinColumns = {#JoinColumn(name = "customer_id", nullable = false)})
private CustomerInfo customerInfo;
#OneToOne(cascade = CascadeType.ALL, targetEntity = CustomerCredentials.class)
#JoinTable(name = "customer_credentials", inverseJoinColumns = {#JoinColumn(name = "customer_id", nullable = false)})
private CustomerCredentials customerCredentials;
// getter, setters etc }
#Entity #Table(name = "customer_info") public class CustomerInfo {
#Id
#GeneratedValue(strategy = GenerationType.IDENTITY)
#Column(name = "id")
private Long id;
// getter, setters etc }
#Entity #Table(name = "customer_credentials") public class CustomerCredentials {
#Id
#GeneratedValue(strategy = GenerationType.IDENTITY)
#Column(name = "id")
private Long id;
// getter, setters etc }
You could change the cascade strategy to any strategy you need. I just left CascadeType.ALL there as an example.
I am facing a hibernate problem in updainting the join table in one to many mapping with hibernate. Below are my two entity class and join table entity class.
ArticleCategoryMap.java
#Entity
#Table(name = "ARTICLECATEGORYMAP")
public class ArticleCategoryMap {
private static final long serialVersionUID = -5653708523600543988L;
#Id
#GeneratedValue(strategy = GenerationType.SEQUENCE)
#Column ( name = "id")
Long id;
#ManyToOne(targetEntity = Article.class, fetch = FetchType.EAGER, optional = true, cascade = CascadeType.PERSIST)
#JoinColumn(name = "ARTICLE_ID", nullable = true, insertable = true, updatable = true)
private Article article;
#ManyToOne(targetEntity = Category.class, fetch = FetchType.EAGER, optional = true, cascade = CascadeType.PERSIST)
#JoinColumn(name = "CATEGORY_ID", nullable = true, insertable = true, updatable = true)
private Category category;
//setter and getter
}
Article.java
#Entity
#Table(name = "ARTICLE")
public class Article {
private long id;
private String title;
private String description;
private String keywords;
private String content;
#Id
#GeneratedValue
#Column(name = "ARTICLE_ID")
public long getId() {
return id;
}
//setter and getter
}
Category.java
#Entity
#Table(name = "CATEGORY")
public class Category {
private long id;
private String name;
#OneToMany(cascade = CascadeType.ALL, fetch=FetchType.EAGER)
#JoinTable(
name = "ARTICLECATEGORYMAP",
joinColumns = #JoinColumn(name = "CATEGORY_ID"),
inverseJoinColumns = #JoinColumn(name = "ARTICLE_ID")
)
#CollectionId(
columns = #Column(name="id"),
type=#Type(type="long"),
generator = "sequence"
)
private Collection<Article> articles;
#Id
#GeneratedValue
#Column(name = "CATEGORY_ID")
public long getId() {
return id;
}
#OneToMany(cascade = CascadeType.ALL, fetch=FetchType.EAGER)
#JoinTable(
name = "ARTICLECATEGORYMAP",
joinColumns = #JoinColumn(name = "CATEGORY_ID"),
inverseJoinColumns = #JoinColumn(name = "ARTICLE_ID")
)
#CollectionId(
columns = #Column(name="id"),
type=#Type(type="long"),
generator = "sequence"
)
// setter an getter
}
Now suppose first time I have 2 elements in article table which is mapping to one entry of the category table. so the join table will look something like
Now due to some reason, I want to update the entry where the article entry will map to a new category ID. So the final DB should look like
So My problem Is how can I update this join table.
If you want one to many relationship (1 category have many articles and 1 article to 1 category) you dont need a join table.
The entity classes should look like that:
Category Entity:
Contains a Set of articles:
#Entity
#Table(name = "CATEGORY")
public class Category {
private long id;
private String name;
#OneToMany(mappedBy="category")
private Set<Article> articles;
......
}
Article Entity:
#Entity
#Table(name = "ARTICLE")
public class Article {
#ManyToOne
#JoinColumn(name="id", nullable=false)
private Category category;
private long id;
private String title;
private String description;
private String keywords;
private String content;
.......
}
For more details take a look at hibernate-one-to-many. Hope this helps.
Also move annotation from methods to fields. This:
private long id;
#Id
#GeneratedValue
#Column(name = "CATEGORY_ID")
public long getId() {
return id;
}
Should be:
#Id
#GeneratedValue
#Column(name = "CATEGORY_ID")
private long id;
public long getId() {
return id;
}
Many to many relationship:
At your database you have 3 tables:
CATEGORY
ARTICLE
ARTICLECATEGORYMAP (join table)
For many to many relationship entities would be:
Category Entity:
#Entity
#Table(name = "CATEGORY")
public class Category {
#Id
#GeneratedValue
#Column(name = "CATEGORY_ID")
private long id;
private String name;
#ManyToMany(cascade = { CascadeType.ALL })
#JoinTable(
name = "ARTICLECATEGORYMAP",
joinColumns = { #JoinColumn(name = "CATEGORY_ID") },
inverseJoinColumns = { #JoinColumn(name = "ARTICLE_ID") }
)
Set<Article > articles = new HashSet<>();
.....
}
Article Entity:
#Entity
#Table(name = "ARTICLE")
public class Article {
#Id
#GeneratedValue
#Column(name = "ARTICLE_ID")
private long id;
private String title;
private String description;
private String keywords;
private String content;
#ManyToMany(mappedBy = "articles")
private Set<Category> categories = new HashSet<>();
.......
}
For more info take a look at many-to-many ralationship
I have a problem with storing OneToMany relationship with Hibernate.
What I got is AdvertisementData entity which looks as follows:
#Entity
#Table(name = "advertisement_data")
public class AdvertisementData {
#Id
#Column(name = "order_id", unique = true, nullable = false)
#GeneratedValue(generator = "gen")
#GenericGenerator(name = "gen", strategy = "foreign", parameters = #Parameter(name = "property", value = "order"))
private Long id;
#OneToMany(fetch = FetchType.EAGER, cascade = CascadeType.MERGE, mappedBy = "advertisementData")
private List<KRPData> krpData;
//setters and getters
}
and KRPData which is defined as follows:
#Entity
public class KRPData {
#Id
#GeneratedValue(strategy = GenerationType.AUTO)
private Long id;
private String description;
#Type(type = "org.hibernate.type.SerializableToBlobType")
private List<String> images;
private String section;
#Type(type = "org.hibernate.type.SerializableToBlobType")
private List<String> filenames;
#ManyToOne
private AdvertisementData advertisementData;
//getters and setters
}
I can see that both entities are stored, however every time I fetch AdvertisementData, the results looks like:
KRPData is returned as PersistentBag without any data.
Hibernate version: 4.2.2.Final
Any ideas what could be the case?
Thank You in advance!