I have Class Product (corresponding to PRODUCT table)
Class Product {
#Id
#Column(name = "PRODUCT_ID")
private Long id;
#Column(name = "NAME")
private String name;
//other attributes
}
I have another class Owner (corresponding to OWNER table)
Class Owner{
#Id
#Column(name = "OWNER_ID")
private Long id;
#Column(name = "NAME")
private String name;
}
I have an intermediate table named PRODUCT_OWNER (a product can have multiple owners).
The PRODUCT_OWNER table is something like this.
_______________________________________
| PRODUCT_ID | OWNER_ID | DISPLAY_ORDER |
|____________|__________|_______________|
Inside my Product class I have written a join statement to perform join using intermediate PRODUCT_OWNER table
#OneToMany(targetEntity = Owner.class, cascade = { CascadeType.ALL, CascadeType.MERGE }, fetch = FetchType.LAZY)
#JoinTable(name = "PRODUCT_OWNER",
joinColumns = { #JoinColumn(name = "PRODUCT_ID") },
inverseJoinColumns = { #JoinColumn(name = "OWNER_ID") })
private Set<Owner> productOwners = new HashSet<Owner>(0);
I have a column in my intermediate table as DISPLAY_ORDER. I want to sort the final Set productOwners using DISPLAY_ORDER. Is this possible in above approach. Please advice.
Hi you can try to add this to your JoinTable
#OneToMany(targetEntity = Owner.class, cascade = { CascadeType.ALL, CascadeType.MERGE }, fetch = FetchType.LAZY)
#JoinTable(name = "PRODUCT_OWNER",
joinColumns = { #JoinColumn(name = "PRODUCT_ID") },
inverseJoinColumns = { #JoinColumn(name = "OWNER_ID") })
#OrderColumn(name="DISPLAY_ORDER")
private List<Owner> productOwners = new HashSet<Owner>(0);
Related
Initial Situation:
I have these two entities, GroceriesList and Product.
GroceriesList:
A GroceriesList can have several products.
#Entity
#Table(name = "lists")
public class GroceriesList {
#Id
#GeneratedValue(strategy = GenerationType.IDENTITY)
#Column(name = "list_id")
private Long listId;
#Column(name = "list_name")
private String listName;
#ManyToMany(cascade = CascadeType.MERGE)
#JoinTable(name = "lists_products",
joinColumns = #JoinColumn(name = "product_id", referencedColumnName = "list_id"),
inverseJoinColumns = #JoinColumn(name = "list_id", referencedColumnName = "product_id")
)
private Set<Product> products;
}
Products:
A Product can be allocated to several GroceriesLists
#Entity
#Table(name = "products")
public class Product {
public enum Category {
Dairy,
Fruit,
Vegetable,
Meat,
Grains
}
// Product ID Column, GenerationType.Identity refers to auto incr in Postgres
#Id
#GeneratedValue(strategy = GenerationType.IDENTITY)
#Column(name = "product_id")
private Long productId;
#Column(name = "product_name")
private String productName;
#Column(name = "product_vendor")
private String productVendor;
#Enumerated(EnumType.STRING)
#Column(name = "product_category")
private Category productCategory;
#Column(name = "product_storedquantity")
private Integer productStoredQuantity;
#JsonIgnore
#ManyToMany(mappedBy = "products")
private List<GroceriesList> groceriesLists;
}
The entities and relationships are stored in three different tables in Postgres(One for Lists, one for products, and one mapping table for the relationships).
The mapping table:
Mapping Table "lists_products"
A sample Product:
Sample Product with Id=4
The problem: I'm trying to create new lists, and that works. However, as you can spot from the Mapping Table Image, Hibernate inserts the IDs into the wrong columns. The list_id in the mapping table is currently getting the product_id, and the product_id in the mapping table is getting the list_id.
I have tried to change the order of column names & references in the #JoinTable annotation in the GroceriesList Entity. However, that throws a mapping Error. I assume my error lies somewhere in that annotation. Interestingly, Hibernate uses the correct SQL-Query. What am I missing here?
After consulting fladdimir's solution, it gave me an idea and I solved my issue. The problem lied within the #JoinColumn annotation, where I thought the "name = ..." property refers to the column name in the database.
#ManyToMany(cascade = CascadeType.MERGE)
#JoinTable(name = "lists_products",
joinColumns = #JoinColumn(name = "product_id", referencedColumnName = "list_id"),
inverseJoinColumns = #JoinColumn(name = "list_id", referencedColumnName = "product_id")
)
private Set<Product> products;
However, that property refers to the declared variable inside the Entity in Spring Boot, i.e. listId
#Id
#GeneratedValue(strategy = GenerationType.IDENTITY)
#Column(name = "list_id")
private Long listId;
So, the working implementation of the #JoinTable Annotation should look like the following, where "name = ..." uses that variable name:
#ManyToMany(cascade = CascadeType.MERGE)
#JoinTable(name = "lists_products",
joinColumns = #JoinColumn(name = "listId", referencedColumnName = "list_id"),
inverseJoinColumns = #JoinColumn(name = "productId", referencedColumnName = "product_id")
)
private Set<Product> products;
I'm working on a Spring Boot App project, which works with diseases and symptoms. So i'm thinking, if a disease can have more symptoms, and also, a symptom can be linked to more diseases, that means i'll have a many-to-many relation in MySql. Also, a symptom can be a general symptom for one disease, and a specific symptom for another (each disease has it's general and specific symptoms). Does this mean i have to have TWO many-to-many relations between diseases and symptoms?
And i'm not certain i really need for each symptom to have a list of diseases where it is a general symptom, and a list where it is a specific one.
I'm pretty new to MySql, so i was wondering if this is the most optimal solution. Any input would be appreciated:
#Entity
public class Disease implements Serializable {
private static final long serialVersionUID = 1L;
#Id
#GeneratedValue(strategy = GenerationType.AUTO)
private String id;
#Column(nullable = false)
private String name;
#Column(nullable = false)
private DiseaseGroup group;
#ManyToMany(fetch = FetchType.LAZY,
cascade = {
CascadeType.PERSIST,
CascadeType.MERGE
})
#JoinTable(name = "disease_generalSymptoms",
joinColumns = { #JoinColumn(name = "disease_id") },
inverseJoinColumns = { #JoinColumn(name = "symptom_id") })
private ArrayList<Symptom> generalSymptoms = new ArrayList<Symptom>();
#ManyToMany(fetch = FetchType.LAZY,
cascade = {
CascadeType.PERSIST,
CascadeType.MERGE
})
#JoinTable(name = "disease_specificSymptoms",
joinColumns = { #JoinColumn(name = "disease_id") },
inverseJoinColumns = { #JoinColumn(name = "symptom_id") })
private ArrayList<Symptom> specificSymptoms = new ArrayList<Simptom>();
}
#Entity
public class Symptom implements Serializable {
private static final long serialVersionUID = 1L;
#Id
#GeneratedValue(strategy = GenerationType.AUTO)
private Long id;
#Column(nullable = false)
private String name;
#ManyToMany(fetch = FetchType.LAZY,
cascade = {
CascadeType.PERSIST,
CascadeType.MERGE
},
mappedBy = "symptom")
private ArrayList<Disease> diseasesWhereThisIsAGeneralSymptom = new ArrayList<Disease>();
#ManyToMany(fetch = FetchType.LAZY,
cascade = {
CascadeType.PERSIST,
CascadeType.MERGE
},
mappedBy = "symptom")
private ArrayList<Disease> diseasesWhereThisIsASpecificSymptom = new ArrayList<Disease>();
}
I have 3 entities User, Order, Item with a mapping like this:
#Entity
public class Item {
#Id
#Access(AccessType.PROPERTY)
private long id; // item id predefined
//..getters and setters
}
#Entity
public class Client {
#Id
#GeneratedValue(strategy = GenerationType.IDENTITY)
private Long id;
//...getters and setters
}
#Entity
public class Order {
#Id
#GeneratedValue(strategy = GenerationType.IDENTITY)
#Column(nullable = false)
#Access(AccessType.PROPERTY)
private Long id;
#ManyToOne(optional = false, fetch = FetchType.LAZY, cascade = {
CascadeType.PERSIST, CascadeType.MERGE,
CascadeType.REFRESH, CascadeType.DETACH
})// without removing
//#JoinColumn(name = "client_id") - works fine
#JoinTable(name = "client_cr_order_cr_item",
joinColumns = #JoinColumn(name = "order_id"),
inverseJoinColumns = #JoinColumn(name = "client_id"))
private Client client;
#NotEmpty
#OneToMany(fetch = FetchType.LAZY, cascade = {
CascadeType.PERSIST, CascadeType.MERGE,
CascadeType.REFRESH, CascadeType.DETACH
})// without removing
#JoinTable(name = "client_cr_order_cr_item",
joinColumns = #JoinColumn(name = "order_id"),
inverseJoinColumns = #JoinColumn(name = "item_id"))
private List<Item> items;
//...getters and setters
}
When I persist order it fails with error:
ERROR: null value in column "item_id" violates not-null constraint
it generate query like this:
insert into client_cr_order_cr_item (client_id, order_id) values ()
i.e. it do not fill out segment_id field by some reason I don't know. But I refer to client not thru 3th table but using FK #JoinColumn(name = "client_id") , then it generate correct query:
insert into order_cr_item (order_id, item_id) values ()
Please, could you explain this behavior? Why mapping of client affect items? Is there any hint to make hibernate persists items to 3th table?
com.mysql.jdbc.exceptions.jdbc4.MySQLIntegrityConstraintViolationException: Cannot add or update a child row: a foreign key constraint fails (ravermeister.artist_recordlabel, CONSTRAINT FK_9dgdyft45droyopxsqijwb1dx FOREIGN KEY (artist_id) REFERENCES artist (id))
Artist class
#Entity
#Repository
#Data
#NoArgsConstructor(force = true)
public class Artist {
#Id
#GeneratedValue(strategy = GenerationType.AUTO)
private long id;
#Column(name = "artist_firstname")
private String artist_firstname;
#Column(name = "artist_secondname")
private String artist_secondname;
#Column(name = "artist_nickname")
private String artist_nickname;
#ManyToMany (fetch = FetchType.LAZY, cascade = {CascadeType.PERSIST, CascadeType.MERGE})
#JoinTable(name = "artist_recordlabel", joinColumns = #JoinColumn(name = "artist_id"),
inverseJoinColumns = #JoinColumn(name = "label_id"))
private Set<RecordLabel> recordLabels;
#ManyToMany (fetch = FetchType.LAZY, cascade = {CascadeType.PERSIST, CascadeType.MERGE})
#JoinTable (name = "artist_musicrelease", joinColumns = #JoinColumn (name = "artist_id"),
inverseJoinColumns = #JoinColumn (name = "musicrelease_id"))
private Set <MusicRelease> musicReleaseSet;
and RecordLabel class
#Entity
#Repository
#Data
#NoArgsConstructor(force = true)
public class RecordLabel {
#Id
#GeneratedValue(strategy = GenerationType.AUTO)
private long id;
#Column(name = "label_name")
private String label_name;
#Column(name = "label_country")
private String label_country;
#ManyToMany(fetch = FetchType.LAZY, cascade = {CascadeType.PERSIST, CascadeType.MERGE})
#JoinTable(name = "artist_recordlabel", joinColumns = #JoinColumn(name = "label_id"),
inverseJoinColumns = #JoinColumn(name = "artist_id"))
private Set<Artist> artistsList;
Please follow this guide for a many-to-many relation
http://www.baeldung.com/hibernate-many-to-many
I think this error means that you are trying to insert/update into RecordLabel table a artist_id value that does not exist in Artist table.
I have one lawyer table which is having id(int) as a primary key and Country table having country_code(String ) as a primary key. I want to create third table using #JoinTable annotation in hibernate with two foreign key in it. But when I run it following error is coming. Not sure how to map one string and one int as foreign keys in third table.
Illegal attempt to map a non collection as a #OneToMany, #ManyToMany or #CollectionOfElements: com.test.common.entities.Country.lawyer
This is my code
#Entity
#Table(name = "lawyer")
public class Lawyer {
#Id
#GeneratedValue(strategy = GenerationType.AUTO)
#Column(name = "lawyer_batch_no")
private int lawyerbatchNo;
#ManyToOne(targetEntity = Country.class, cascade = { CascadeType.ALL })
#JoinTable(name = "lawyer_cscd", joinColumns = {
#JoinColumn(name = "lawyer_batch_no", referencedColumnName = "lawyer_batch_no") }, inverseJoinColumns = {
#JoinColumn(name = "country_code", referencedColumnName = "country_code") })
private Country country;
getter setter...
}
#Entity
#Table(name = "country")
public class Country {
private static final long serialVersionUID = 1L;
#Id
#Column(name = "country_code")
protected String country_code;
#Column(name = "abbreviation")
protected String abbreviation;
#Column(name = "name", nullable = false)
protected String name;
#OneToMany(cascade = CascadeType.ALL, mappedBy = "country")
protected Set<State> state = new HashSet<State>();
#OneToMany(targetEntity = Lawyer.class, cascade = { CascadeType.ALL }, orphanRemoval = true)
#JoinTable(name = "lawyer_cscd", joinColumns = {
#JoinColumn(name = "country_code", referencedColumnName = "country_code") }, inverseJoinColumns = {
#JoinColumn(name = "lawyer_batch_no", referencedColumnName = "lawyer_batch_no") })
private Lawyer lawyer;
getter setter....
}
The error indicates that private Lawyer lawyer needs to be a collection as it's a #OneToMany relationship. In the Country class, the last relationship should be
#OneToMany(targetEntity = Lawyer.class, cascade = { CascadeType.ALL }, orphanRemoval = true)
#JoinTable(name = "lawyer_cscd", joinColumns = {
#JoinColumn(name = "country_code", referencedColumnName = "country_code") }, inverseJoinColumns = {
#JoinColumn(name = "lawyer_batch_no", referencedColumnName = "lawyer_batch_no") })
private Set<Lawyer> lawyer;
// or a Collection/List/etc.