I'm trying to have a localization table that is linked to from multiple tables.
I'm realizing that the problem is that I'm using the ID of Localization (eg Localization_Id) so I can't link to different localizations without some other key. Should I use a join table or some other sequential id in the database somehow? Not sure what the best approach is using JPA.
Thanks in advance.
#Entity
public class MyEntityWithLocalization {
#Id
#GeneratedValue(strategy = GenerationType.AUTO)
long id;
#OneToMany(fetch = FetchType.EAGER, cascade={CascadeType.ALL})
#JoinColumn(name="LOCALIZATION_KEY")
List<Localization> field1;
#OneToMany(fetch = FetchType.EAGER, cascade={CascadeType.ALL})
#JoinColumn(name="LOCALIZATION_KEY")
List<Localization> field2; //can't be unique from field one as it links to the MyEntityWithLocalization id.
#OneToMany(fetch = FetchType.EAGER, cascade={CascadeType.ALL})
#JoinColumn(name="LOCALIZATION_KEY")
List<Localization> field3; //can't be unique from field one as it links to the MyEntityWithLocalization id.
}
#Entity
public class Localization {
#Id
#GeneratedValue(strategy = GenerationType.AUTO)
long id;
String language;
String string;
public Localization(String language, String string) {
this.language = language;
this.string = string;
}
public Localization(){
}
}
This creates a localization_key in the localization table but that is just keyed to the ID of the MyEntityWithLocalization - it needs to be another unique value which makes me believe a join table may make sense in this case.
create table localization (
id number(19,0) not null,
language varchar2(255),
string varchar2(255),
localization_key number(19,0),
primary key (id)
);
Hmm. Why not just split the entity into constant and localizable part? Something like this:
#Entity
class MyEntity{
#Id
#GeneratedValue(strategy = GenerationType.AUTO)
long id;
#OneToMany
#MapKeyColumn
Map<String, MyEntityLocalization> localizations;
}
#Embeddable
class MyEntityLocalization {
String field1;
String field2;
String field3;
}
Where the localizations field has the map from the language to the localization? The other way is using Hibernate-specific annotations:
#Entity
class MyEntityWithLocalization {
#Id
#GeneratedValue(strategy = GenerationType.AUTO)
long id;
#OneToMany
#MapKeyColumn(name="language")
#WhereJoinTable(clause = "key=1")
Map<String, String> field1;
#OneToMany
#MapKeyColumn(name="language")
#WhereJoinTable(clause = "key=2")
Map<String, String> field2;
}
#Entity
public class Localization {
#Id
#GeneratedValue(strategy = GenerationType.AUTO)
long id;
long key;
String language;
String string;
}
Related
I have some Entities looks like this. Very abstract:
#Entity
class Man {
#Id
String name;
#OneToMany(fetch = FetchType.EAGER, mappedBy = "name", cascade = CascadeType.ALL)
List<Car> carList;
}
#IdClass(TypeId.class)
#Entity
class Car {
#Id
#NonNull
String name;
#Id
#NonNull
String class;
#ManyToOne(fetch = FetchType.EAGER, optional = false)
#JoinColumn(name = "class",
referencedColumnName = "class",
insertable = false,
updatable = false)
Engine engine;
}
#Entity
class Engine() {
#Id
#NonNull
String class;
String type;
Integer count;
}
class TypeId {
String name;
String class;
}
I need to construct #Query - select MAN with condition: if Engine types are equals, I need to take one Car with less Engine count. And return Man with only one Car if condition is met. Otherwise return Man with all cars.
The table was not being created for the following model despite following the correct procedure
Model
#AllArgsConstructor
#NoArgsConstructor
#Data
#Entity
public class Product {
#Id
#GeneratedValue(strategy = GenerationType.AUTO)
Integer pid;
String name;
String desc;
double price;
}
So I was creating an entity class for JPA where there was a field name desc. I was using MySQL database. But for some reason, I was getting the following error.
The model
#AllArgsConstructor
#NoArgsConstructor
#Data
#Entity
public class Product {
#Id
#GeneratedValue(strategy = GenerationType.AUTO)
Integer pid;
String name;
String desc;
double price;
}
Later I changed the field name and the whole thing was working. The ORM was automatically creating the table.
The updated model that works
#AllArgsConstructor
#NoArgsConstructor
#Data
#Entity
public class Product {
#Id
#GeneratedValue(strategy = GenerationType.AUTO)
Integer pid;
String name;
String description;
double price;
}
I want to use orderNumber in ProductRepository but I keep getting SQL error. I mapped both sides.
this is product entity.
#Entity
public class Product extends BaseEntity {
#Id
#GeneratedValue
#Column(name = "product_id")
private Long id;
#ManyToOne
#JoinColumn(name = "orderItem_id")
private OrderItem orderItem;
this is orderItem entity.
#Entity
public class OrderItem extends BaseEntity {
#Id
#GeneratedValue
#Column(name = "orderItem_id")
private Long id;
private String orderNumber
#OneToMany(mappedBy = "orderItem", cascade = CascadeType.ALL, orphanRemoval = true)
#Builder.Default
private List<Product> products = new ArrayList<Product>();
this is query in ProductRepository.
#Query(value = "SELECT * FROM OrderItem a, Product b WHERE a.orderItem_id = b.orderItem_id", nativeQuery = true)
Product findByOrderNumber(String orderNumber);
Alternatively, you can try query by a method as shown below, you don't need to use the #Query in this case.
ProductRepository
Product findByOrderItemOrderNumber(String orderNumber);
you can find more details here
#Entity
#Table(name = "project")
public class Project {
#Id
#Column(name = "project_id")
#GeneratedValue(strategy = GenerationType.AUTO)
private int id;
#OneToOne
#JoinColumn(name = "idea_id", referencedColumnName = "idea_id")
#JsonIgnore
private Idea idea; .......}
And
#Entity
#Table(name = "idea")
public class Idea {
#Id
#Column(name = "idea_id")
#GeneratedValue(strategy = GenerationType.AUTO)
private int id;
#Size(max = 240)
#NotNull
private String description;
#OneToOne(cascade = CascadeType.ALL)
#JoinColumn(name = "project_id", referencedColumnName = "project_id")
private Project project; ..........}
What is wrong with my hibernate relationships in these two classes? This is example of relationship that I want to implement.
And this is actual tables that I get with these relationships:
Idea table:
And Project table:
How to get rid of null values in idea_id column in project table?
Challenge:
I want to create a query that selects Topics that match both the keyword ID´s "Java" and "sql", the Topic with ID = 1 matches both keywords "Java" and "Sql.
I have implemented two simple entities Topic and Keyword. They have a bidirectional ManyToMany relationship:
#Entity
#Table(name = "Topic")
public class Topic implements Serializable {
private static final long serialVersionUID = 1L;
#Id
#GeneratedValue(strategy = GenerationType.AUTO)
#Column(name = "topicID")
private Long id;
#Column(name = "topicTitle")
private String title = "";
#ManyToMany
#JoinTable(name = "Join_Topic_Keyword",
joinColumns = #JoinColumn(name = "Topic_ID"),
inverseJoinColumns = #JoinColumn(name = "Keyword_ID"))
private Set<Keyword> keywords;
}
#Entity
#Table(name = "Keyword")
public class Keyword implements Serializable {
private static final long serialVersionUID = 1L;
#Id
#GeneratedValue(strategy = GenerationType.AUTO)
#Column(name = "keywordID")
private String id;
#ManyToMany(mappedBy = "keywords")
private Set<Topic> topics;
}
Here is the structure table.
And This is the result from Join_Topic_Keyword