I have an entity which has map list with sub enitities. When I want to delete this entity , I've got
Cannot delete or update a parent row: a foreign key constraint fails (kobalt.category_categoryitem,
error and I use hibernate. Is there anyone who can solve this problem ?
#Entity
public class Product implements BaseEntity {
private static final long serialVersionUID = 1L;
#Id
#GeneratedValue
private int id;
private int kobilId;
private String code;
#Column(unique = true)
private long barcode;
private String productName;
#Column
#OneToMany(cascade = CascadeType.ALL, fetch = FetchType.EAGER)
#Fetch(value = FetchMode.SUBSELECT)
#Cascade(org.hibernate.annotations.CascadeType.DELETE)
private Map<Category, CategoryItem> itemList;
Looks like relationship structure is not correct in your case. When you are trying to delete foreign key corresponding value it can't delete primary key corresponding value. In cascade rule relationship should be like as when you delete primary key corresponding attribute then it should delete all foreign key corresponding attributes. But can't be vice-versa. That is your case i think so try to correct your relationships. For example consider "employee - address" relationship where employee has array of address. So relationship should be like as when employee is deleted, all the corresponding address should vanish. But on the other hand if relationship is not correct and you try to delete an address then it can't be possible to delete employee, as a result you'll get such exception as in your case.
Related
I have two tables that already exist inside postgres, lets call the Table A and Table B. One column of Table B has a foreign key constraint in that it has to be the primary key of Table A. Thus there is a many-to-one relationship between B and A, where multiple records in Table B correspond to one record of Table A.
The Entity for both these tables are defined as follows.
public class TableA implements Serializable {
#Id
#GeneratedValue(strategy = GenerationType.IDENTITY)
#Column(name = "user_id")
private Long userId;
#Column(name = "name")
private String name;
#Column(name = "email")
private String email;
#Column(name = "phone_number")
private String phoneNumber;
}
TableB's entity is defined as follows:
public class Shots implements Serializable {
#Id
#GeneratedValue(strategy = GenerationType.IDENTITY)
#Column(name = "item_id")
private Long itemId;
#Column(name = "user_id")
private Long userId;
}
Where userId is the foreign key mapping to the primary key user_id in Table A.
These constraints have already been defined in the underlying postgres database, so i didn't consider using the #ManyToOne annotation relationship (still trying to wrap my head around it).
The way i currently handle the case when a foreign key constraint violation occurs is by doing the following:
try {
tableBrepository.save(newShot);
} catch (ConstraintViolationException ex) {
logger.error("Violating foreign key constraint" + ex.getMessage());
}
My question is, is there a better way to check for this violation? Is there anything i can do to generally better structure the foreign key constraint in Spring Data JPA?
Thus there is a many-to-one relationship between B and A, where multiple records in Table B correspond to one record of Table A.
This kind of stuff in JPA entities is handled with #ManyToOne annotation. You usually do not refer to any id field directly but tell JPA what there should be. So in your class TableB (or should I call it... Shots?) should be something like:
#ManyToOne
private TableA tableA;
// and get rid of this
// #Column(name = "user_id")
// private Long userId;
And optionally - so not necessarily - you could have, in your TableA:
#OneToMany
private List<TableB> tableBsOrShouldICallYouShots;
I am not sure what is your actual problem but when setting and referring to id fields directly might cause your difficulties.
Now if you -for example- use repository to find some TableB you can then after that just do
tableB.getTableA()
And when saving you would before that do:
tableB.setTableA(somSortOftableA);
// so not tableB.setUserId(someLongIdFOrtableA);
Now the point is that there is no problem with referential integrity because you do not need to know any IDs and you cannot set any wrong ID. Unless you first need to fetch TableA by id before setting it to TableB but in that case you would still not set any IDs.
I am trying to join to Hibernate Entities in a OneToOne Mapping. I am able to fetch the data for a given primary key from the Main Entity, the joining entity, however, returns null. I am new to hibernate and any help will be appreciated.
I have two Tables,
PT_CORE
Primary Key: ptId - Integer;
Foreign Key: stId(ST_AUX) - Integer;
Columns: ptId, ptName
ST_AUX
Primary Key: stId;
Columns: stId, stName
The two tables get populated by other applications and mine is a read-only operation.
Below is my first Entity class(PtCore.java)
#Entity
#Table(name="PT_CORE")
public class PtCore implements Serializable{
#Id
#Column(name="ptId", nullable = false)
private int id;
#Column(nullable=false)
private int stId; //The Foreign key column
#OneToOne
#JoinTable( name = "core_aux", joinColumns = {#JoinColumn(Name="ptId")},
inverseJoinColumns = {#JoinColumn(Name="stId")}
)
private StAux staux;
//Getters, setters and toString() for above
}
StAux is another Entity, defined as below,
#Entity
#Table(name="ST_AUX")
public class StAux implements Serializable {
#Id
#Column(nullable=false)
private Integer stId;
#OneToOne
private PtCore ptcore;
#Column
private String stName;
//Getters, Setters and toString follow.
}
I do below in the Service method:
PtCore obj = (PtCore) session.get(PtCore.class,1);
System.out.println(obj);
In the Results, I get the value of ptName, but the stAux class variables are null, Indicating that the join does not work as expected.
First of all you have the mapping information existing in your PT_CORE. And I assume it is something like FOREIGN KEY (stid) REFERENCES (stid). If you want to use existing schema and existing data I guess there is no mapping table core_aux really existing. At least you did not mention it. However it is visible as #JoinTable annotation but still there is this above mentioned foreign key which seems to be the real mapping (so again not the join table).
I suggest the following
remove this
#Column(nullable=false)
private int stId; //The Foreign key column
from your PtCore. I think it is not needed. Also in PtCore, remove the #JoinTable (because what I told above) and add mapping informaiion to #OneToOne annotation, like:
#OneToOne
#JoinColumn(name = "stid")
private StAux staux;
from your PT_CORE.
Then in StAux alter also a bit:
#Id
#Column(name = "stid") // this might not be needed but if there is like "st_id"...
private Integer stId; // so just for sure
#OneToOne(mappedBy = "staux")
private PtCore ptcore;
Because you have existing tables and constraints there might raise errors if hibernate tries to auto-generate those again by JPA instructions.
Check this for example for more information.
UPDATE: just realized also that in your title is #OneToMany but in your code is #OneToOne.
So you might want to elaborate your question and/or title a bit.
In your relation, the owning side is PtCore, the inverse side is StAux.
In bidirectional OneToOne relations, the inverse side has to have the mappedBy attribute. Actually, the mappedBy attribute contains the name of the association-field on the owning side.
So, you must change your inverse side code (StAux Entity). You have to add mappedBy attribute to #OneToOne in StAux class:
#OneToOne(mappedBy="staux")
private PtCore ptcore;
There is 2 entity
Product(product_id(PK),product_name..)
Store(product_id(PK,FK),product_quantity,...)
I need #OneToOne, so i do this
public class Product{
#Id
#Column(name="PRODUCT_ID")
#OneToOne(mappedBy="product")
private int product_id;
....
}
public class Store{
#Id
#OneToOne(cascade = CascadeType.ALL)
#JoinColumn(name = "PRODUCT_ID")
private Product product;
}
Compilier says #Column(s) not allowed on a #OneToOne property: ......shopdb.entity.Product.product_id
What is the problem?
I just moved #OneToOne(mappedBy="product") to new created field in Product
private Store store;
I dont understand how it works correct;
Why i need to use 3 fields instead of 2?
You can't mark a column defined with #JoinColumn as #Id. This is applicable only to columns defined with #Column annotation.
It is also a bit strange what are you trying to do. You are basically making the produc_id primary key for both entites, so then why don't make just one?
From what I can see here, I believe that the Store should have a store id property which will be used as primary key.
It`s possible to create one map with hibernate #ManyToOne just like this:
public class IndicadorAtos {
#JsonIgnore
#Id
#Column(name="cod_ato_praticado")
private Integer codAtoPraticado;
#Column(name="descricao_ato")
private String ato;
#JoinColumn(name = "cod_ato", referencedColumnName = "cod_ato")
#ManyToOne
#Fetch(FetchMode.SUBSELECT)
private Atos atos;
}
But in some cases I dont have association or in my table IndicadorAtos have one code, that don`t existis in table Atos
this is my tables:
create table IndicadorAtos (
codAtoPraticado integer primary key,
ato varchar(250),
cod_ato integer
);
create table Atos(
cod_ato integer primary key.
name varchar(250)
)
I try to create this join:
Select t FROM IndicadorAtos t , Atos a where t.cod_ato = a.cod_ato, but I need to return all records from my IndicadorAtos, and with this select he only return all itens that have one item in Atos.
tks
It`s possible to create one map with hibernate #ManyToOne
Yes; it is called unidirectional relationship.
If I understood your question properly, you want to select all entries from IndicadorAtos with possibly associated entries from Atos. You can achieve this by using left join as follows:
SELECT t FROM IndicadorAtos t LEFT JOIN t.atos at
provided that you have an entity Atos defined like:
#Entity
public class Atos {
#Id #GeneratedValue
private int cod_ato;
private String name;
// getters and setters
}
i am trying on many to many relationship, Team member can work on multiple projects and a project can have multiple team member , the table structure is as follows,
create table TBL_PROJECT_ONE(
id integer primary key generated always as identity(start with 12,increment by 3),
name varchar(50)
)
create table TBL_TEAM_MEMBER_ONE(
id integer primary key generated always as identity(start with 7,increment by 5),
name varchar(50),
salary integer
)
create table EMP_PRJ_CADRE(
MEMBER_ID integer references TBL_TEAM_MEMBER_ONE,
PRJ_ID integer references TBL_PROJECT_ONE,
CADRE varchar(10),
constraint PK_001_EMP_TEAM primary key (MEMBER_ID,PRJ_ID)
)
Here i have created a new table just to store the relationship,
Now please follow the Employee entity,
#Entity
#Table(name="TBL_TEAM_MEMBER_ONE")
public class EmployeeEntityFour implements Serializable{
public EmployeeEntityFour(){}
public EmployeeEntityFour(String empName,Integer salary){
...
..
}
#Id
#GeneratedValue(strategy= GenerationType.IDENTITY)
#Column(name="ID")
private Integer empId;
#Column(name="NAME")
private String empName;
#Column(name="SALARY")
private Integer empSal;
#ElementCollection(fetch= FetchType.LAZY)
#CollectionTable(name="EMP_PRJ_CADRE")
#MapKeyJoinColumn(name="PRJ_ID")
#Column(name="CADRE")
private Map<ProjectEntityOne,String> employeeCadre;
...
..
.
}
Please follow the mapping for Project Entity,
#Entity
#Table(name="TBL_PROJECT_ONE")
public class ProjectEntityOne implements Serializable{
public ProjectEntityOne(){}
public ProjectEntityOne(String name){
this.projectName = name;
}
#Id
#GeneratedValue(strategy= GenerationType.IDENTITY)
#Column(name="ID")
private Integer projectId;
#Column(name="NAME")
private String projectName;
#ElementCollection(fetch= FetchType.LAZY)
#CollectionTable(name="EMP_PRJ_CADRE")
#MapKeyJoinColumn(name="MEMBER_ID")
#Column(name="CADRE")
private Map<EmployeeEntityFour,String> employeeCadre;
....
..
.
}
In main method testing the code written is as follows,
ProjectEntityOne proj = new ProjectEntityOne("Citi Grand Central");
Map<EmployeeEntityFour,String> cadreMap = new HashMap<EmployeeEntityFour,String>();
cadreMap.put(new EmployeeEntityFour("Murlinarayan Muthu",34000), "Senior Software Engineer");
cadreMap.put(new EmployeeEntityFour("Gopalkrishna Rajnathan",64000), "Software Engineer");
cadreMap.put(new EmployeeEntityFour("Premanna Swaminathan",94000), "Project Manager");
proj.setEmployeeCadre(cadreMap);
em.persist(proj);
but i am getting an error which is
ERROR: 'PROJECTENTITYONE_ID' is not a column in table or VTI 'APP.EMP_PRJ_CADRE'.
When in both the entities i have specified #MapKeyJoinColumn than too i am getting an error as improper column for the third table.
Where i am missing
It somehow worked, i had to do some changes in the code,
first, the edited code in Entity ProjectEntityOne is as follows,
#ElementCollection(fetch= FetchType.LAZY)
#CollectionTable(name="EMP_PRJ_CADRE",joinColumns=#JoinColumn(name="PRJ_ID"))
#MapKeyJoinColumn(name="MEMBER_ID")
#Column(name="CADRE")
private Map<EmployeeEntityFour,String> employeeCadre;
What i have done here is i added #JoinedColumn in #CollectionTable,
Second change i did in Entity EmployeeEntityFour, the change is I removed Map of PorjectEntityOne from it,
in test,
i can save Project with Employee mapping but here all the employees should be already saved one.
i.e. the key of map
Map<EmployeeEntityFour,String> employeeCadre;
should be already persisted
and than we can persist project entity.
On employeeCadre in EmployeeEntityFour you need a #JoinColumn(name="MEMBER_ID") and you would also need a #JoinColumn(name="PRJ_ID") in the ProjectEntityOne employeeCadre.
But, I would not model it this way. First of all you cannot have a bi-directional ElementCollection mapping, and ElementCollection can only be owned by one side. The best solution would be to define an Cadre entity mapping to EMP_PRJ_CADRE table and have a OneToMany to it from both sides, and have it have a ManyToOne to each.
Alternatively you may use a ManyToMany with a MapKeyColumn, but I think you would be better off having an entity.