Fetch Parent even when child is absent - java

After many attempts I'm here to seek a help from any of you. A solution is very much needed.
I have a parent (Patient) entity and its child (Address) entity.
Where I want to fetch all the registered patients and address details, where address details may be null. Meaning, Patient may not have address details..
I have written logic by using CriteriaBuilder like this
CriteriaBuilder builder = this.em.getCriteriaBuilder();
CriteriaQuery<Object[]> query = builder.createQuery(Object.class);
Root<TaskImpl> patientRoot = query.from(Patient.class);
Root<ContentImpl> addressRoot = query.from(Address.class);
query.multiselect(patientRoot.get("patinetId"),patientRoot .get("patinetName"),
addressRoot.get("city));
Predicate patAddressJoinPred = builder.equal(
patientRoot.get("patientId"),
addressRoot.get("patient").get("patientId"));
query.where(builder.and(patAddressJoinPred));
please find Patient and Address entities for your ref,
Patient.java-----------------
#Entity
public class Patinet{
#Id
private Long patentId;
private String patientName;
}
------------------------------
Address.java------------------
#Entity
public class Address{
#Id
private Long addressId;
private String city;
#OneToOne(FetchType.Lazy)
#JoinColumn("patinet_id")
private Patient patient;
}
-------------------------------
But after the criteria builder, I have applied cross join on Address entity which will be a performance problem and I cannot get details of patients which don't have address details..
for simplicity, the sample data and my required output is given bellow.
Patient table
-------------
id | name
-------------
1 | Sameul
2 | Jhon
3 | khan
4 | Lee
-------------
Address table
-----------------------
id | city | patient_id
-----------------------
1 | Blz | 1
2 | Stn | 3
required out put
-------------------------
id | patientName | city
-------------------------
1 | Sameul | blz
2 | Jhon |
3 | khan | stn
4 | Lee |
But getting like this
-------------------------
id | patientName | city
-------------------------
1 | Sameul | blz
3 | khan | stn
-------------------------
Will be waiting for your valuable solution
Thank you..

It looks you are using inner join, you should use outer joins
Something like,
final Root<Patient> patient = criteriaQuery.from(Patient.class);
Join<Patient, Address> join1 = patient .join("joinColumnName", JoinType.LEFT);
Predicate predicate = criteriaBuilder.equal(Address.<String> get("patient_id"), patient;
criteria.add(predicate);
criteriaQuery.where(predicate);
criteriaQuery.distinct(true);
Hope it resolves your query. I have not tested it but should work fine.

Related

How to do a hibernate saving without duplicate records in a different table

Can someone help on the following scenario, please? Let say I have table 1
|----------------|--------------|------------|--------|
| Salesman | Product | Year | Sold |
|----------------|--------------|------------|--------|
| John | prod1 | 2015 | 2000 |
|----------------|--------------|------------|--------|
| John | prod1 | 2016 | 2000 |
|----------------|--------------|------------|--------|
| John | prod2 | 2015 | 2000 |
|----------------|--------------|------------|--------|
| John | prod2 | 2016 | 2000 |
|----------------|--------------|------------|--------|
| Tracy | prod1 | 2015 | 2000 |
|----------------|--------------|------------|--------|
| Tracy | prod1 | 2016 | 2000 |
|----------------|--------------|------------|--------|
| Tracy | prod2 | 2015 | 2000 |
|----------------|--------------|------------|--------|
| Tracy | prod2 | 2016 | 2000 |
|----------------|--------------|------------|--------|
As you can see in table 1, Salesman, Product are not unique key. However, now I want to do a saving to table 2 with some detailed info for Salesman and Product combination. In other words, I want the Salesman and product is unique in table 2.
|----------------|--------------|--------|
| Salesman | Product |priority|
|----------------|--------------|--------|
| John | prod1 | true |
|----------------|--------------|--------|
| John | prod2 | false |
|----------------|--------------|--------|
| Tracy | prod1 | true |
|----------------|--------------|--------|
| Tracy | prod2 | true |
|----------------|--------------|--------|
Is there anyway I can use the following entity for hibernate.
#Entity
#Table(name = "table1")
public class EntityTable1() {
private String salesman;
private String product;
private int year;
private int sold;
private List<EntityTable2> entityTable2;
....
}
and
#Entity
#Table(name = "table2")
public class EntityTable2() {
private String salesman;
private String product;
private boolean priorityTarget;
....
}
Is there anyway, when I save EntityTable1 objects, I save EntityTable2 cascade and also make sure table2 doesn't have duplicate rows? I understand there will be other ways to change the entity or DB design. However, since I am working on a project that have been built and used by other team, I cannot simply change table 1 schema. But I can do whatever for table 2. Please help. Thanks.
It very much depends on what you want to be unique in EntityTable2. Do you want the combination of all your fields to be unique? In that case you would need something like this:
#Table(
name = "table2",
uniqueConstraints = {#UniqueConstraint(columnNames = {"salesman", "product", "priorityTarget"})}
)
Do you want the individual fields to be unique? Then you would want something like this:
#Table(
name = "table2",
uniqueConstraints = {
#UniqueConstraint(columnNames = "salesman"),
#UniqueConstraint(columnNames = "product"),
#UniqueConstraint(columnNames = "priorityTarget")
}
)
And of course you can mix and match the above.
Hope this helps!
You should be able to achieve this using Hibernate Interceptor. You can save the objects of table2 in the onSave event of table1.
For uniqueness you will need to check if the record exists, if it exists, update the same record else create a new one.

Query Predicate in QueryDSL

The environment is Java, Spring-boot, Hibernat, QueryDSL, MySQL.
I have table structure
Episode
+----+-------------+--------
| id | address_id | eventno
+----+-------------+--------
| 5 | 27 | F123
| 6 | 30 | F456
| 7 | 45 | F789
+----+-------------+--------
#Entity
public class Episode {
#Id
#GeneratedValue(strategy = GenerationType.IDENTITY)
private Long id;
#NotEmpty
private String eventno;
#ManyToOne(cascade = CascadeType.ALL)
private Address address;
Episode_Person
+----+--------------+--------------+------------+-----------+
| id | episode_role | primary_flag | episode_id | person_id |
+----+--------------+--------------+------------+-----------+
| 19 | Buyer | | 5 | 1 |
| 20 | Subject | | 5 | 2 |
| 23 | Witness | | 6 | 3 |
| 24 | Child | | 6 | 4 |
| 27 | Buyer | | 5 | 3 |
| 63 | Investor | | 5 | 4 |
| 64 | Subject | | 7 | 1 |
| 65 | Subject | | 7 | 3 |
#Entity
public class EpisodePerson {
#Id
#GeneratedValue(strategy = GenerationType.IDENTITY)
private Long id;
#ManyToOne
#Valid
private Person person;
#ManyToOne
private Episode episode;
Person
+----+-----------+----------+
| id | firstname | surname |
+----+-----------+----------+
| 1 | Clint | eastwood |
| 2 | Angelina | joilee |
| 3 | Brad | pitt |
| 4 | Jennifer | aniston |
#Entity
#Table(uniqueConstraints = #UniqueConstraint(columnNames = {"nia"}))
public class Person {
#Id
#GeneratedValue(strategy = GenerationType.IDENTITY)
private Long id;
private String surname;
private String firstname;
private String gender;
So each episode has multiple people. And the join table is Episode_Person.
My UI has a datatable with a filter on each column:
The filtering already works on Event and Address. And looks like this predicate in QueryDSL:
BooleanBuilder where = new BooleanBuilder();
if (pagination.getFilterBy().getMapOfFilters().get("eventno")!=null) {
where.and(qEpisode.eventno.containsIgnoreCase(pagination.getFilterBy().getMapOfFilters().get("eventno")));
}
if (pagination.getFilterBy().getMapOfFilters().get("address")!=null) {
where.and(qEpisode.address.formattedAddress.containsIgnoreCase(pagination.getFilterBy().getMapOfFilters().get("address")));
}
where.and(qEpisode.creatingUser.eq(user));
List<Episode> e = episodeRepository.findAll(where);
How would I now add a 3rd predicate for case name where case name is constructed of the first two people returned in the collection of people against a episode?
UPDATE
For clarification the DTO thats backs the UI view contains the "casename" attribute. It is created in the service layer when Domain objects are converted to DTO:
episodeDashboard.setNames(episodePersonList.get(0).getPerson().getSurname().toUpperCase() +" & " +episodePersonList.get(1).getPerson().getSurname().toUpperCase());
Not easily unless you delegate some of the processing to the database.
If we can get the case_name property to be populated at the database tier rather than as a derived property in the application logic then the front-end code becomes trivial.
We can do this by means of a view. The exact definition of this will depend on your database however the output would be something like this:
episode_summary_vw
+------------+-------------------------+
| epsiode_id | case_name |
+------------+-------------------------+
| 5 | Eastwood & Joilee|
| 6 | Pitt & Aniston|
| 7 | Aniston & Pitt|
+------------+-------------------------+
For Oracle it looks like LISTAGG function is what you would want and for MySQL the GROUP_CONCAT functions. In MySQL then I think this would look something like:
CREATE VIEW episode_summary_vw as
SELECT ep.episode_id, GROUP_CONCAT(p.surname SEPARATOR ' & ')
FROM episode_person ep
INNER JOIN person p on p.id = ep.person_id
GROUP BY ep.episode_id;
-- todo: needs limit to first 2 records
Once we have a view then we can simply map the case_name to the Episode entity using the #SecondaryTable functionality of JPA:
#Entity
#Table(name = "episodes")
#SecondaryTable(name = "episode_summary_vw", primaryKeyJoinColumna = #PrimaryKeyJoinColumn(name="episode_id", reference_column_name="id"))
public class Episode {
#Column(name ="case_name", table = "episode_summary_vw")
private String caseName;
}
You then filter and sort on the property as for any other field:
if (pagination.getFilterBy().getMapOfFilters().get("caseName")!=null) {
where.and(qEpisode.caseName.containsIgnoreCase(pagination.getFilterBy().
getMapOfFilters().get("caseName")));
}

Dynamic #Table name based on input

We have Hibernate based application where due to a large data set, two sets of tables are created where user_id will either be mapped in the UserTickets table or RestOfWorldTickets table.
Would like to know how #Table on the entity java objects can be dynamically mapped based on some user selection.
#Entity
#Table(name = "**UserTickets**")
public class UserTickets {
#Id
#Column("Internal_id")
#GeneratedValue(strategy = IDENTITY)
private int internalId;
#Column("user_id")
private int userId;
#Column("state")
private String state;
#Column("city")
private String city;
#Column("address")
private String address;
#Column("ticketNumber")
private String ticketNumber;
..
// Setters and Getters
}
UserTickets DB Table
Internal_id | User_id | State | City | Address | ticket_number | ...
101 | 1025 | AZ | Tuscan | .. | 10256912 |
102 | 1026 | NC | Durham | .. | 10256983
RestOfWorldTickets DB Table
Internal_id | User_id | State | City | Address | ticket_number |..
101 | 1058 | {null} | London | .. | 102578963 |..
102 | 1059 | {null} | Berlin | .. | 112763458 |..
The user and table mapping are now defined in a new table.
TableMapping Database table.
Internal_id | User_id | TableMapped |
1 | 1025 | UserTickets |
2 | 1026 | UserTickets |
3 | 1058 | RestOfWorldTickets |
4 | 1059 | RestOfWorldTickets |
So, using the UserTickets result set, how I map #Table attribute on the UserTickets Java object dynamically so that my Criteria API queries will work automatically without changing them to HQL queries?
Maybe using Interceptors http://docs.jboss.org/hibernate/orm/3.5/javadocs/org/hibernate/Interceptor.html?
I am quite unsure what you actually need but i try to give my solution based on a few quesses. Changing #Table dynamically is not -afaik- possible but if i guessed right you could have some benefit of inheritance in this case:
1st modify UserTickets to allow inheritance
#Entity
//#Table(name = "**UserTickets**")
#Inheritance(strategy=InheritanceType.TABLE_PER_CLASS)
public class UserTickets {
#Id // this annotation was missing from yours ?
#Column(name="Internal_id")
#GeneratedValue(strategy = GenerationType.SEQUENCE)
// identity generated problems in openjpa so i changed it to SEQUENCE
private int internalId;
#Column(name="user_id") private int userId;
#Column(name="state") private String state;
#Column(name="city") private String city;
#Column(name="address") private String address;
#Column(name="ticketNumber") private String ticketNumber;
}
2nd create a new entity
#Entity
public class RestOfWorldTickets extends UserTickets {
// yes i am just an empty class, TABLE_PER_CLASS gives me the fields
}
This allows you to use criteriaqueries against UserTickets but in addition the queries are done against RestOfWorldTickets also. So now when you search with user id result set will contain results from both tables. Checking/ loggin -for example with instanceof operator- you can see which one the ticket is.
"Disclaimer" i am using and testing with openjpa so there can be some differences/probkems with this solution...

modelmapper-jooq and handling 'null' fields

I'm using modelmapper-jooq to map jOOQ records to custom pojos. Let's assume I have table like
| name | second_name | surname
----------------------------
1 | Mary | Jane | McLeod
----------------------------
2 | John | Henry | Newman
----------------------------
3 | Paul | | Signac
----------------------------
4 | Anna | | Pavlova
so the second_name can be null. My Person POJO looks like:
public class Person {
private String name;
private String secondName;
private String surname;
// assume getters and setters
}
When I map Result<Record> into Collection<Person>, every element in this collection has secondName equal null. When I map only first two rows, everything is OK. How to handle it properly, so the secondName field is null only when corresponding field in database is null? I've checked that fields in Record instances have proper values. I configure modelmapper in this way:
ModelMapper modelMapper = new ModelMapper();
modelMapper.getConfiguration().addValueReader(new RecordValueReader());
modelMapper.getConfiguration().setSourceNameTokenizer(NameTokenizers.UNDERSCORE);
Also I'm doing mapping like:
//...
private final Type collectionPersonType = new TypeToken<Collection<Person>>() {}.getType();
//...
Result<Record> result = query.fetch();
return modelMapper.map(result, collectionPersonType);

Hibernate many-to-many join with condition

+-------+ +--------------| +-------+
| BOY | | BOY_GIRL | | GIRL |
+-------+ +--------------| +-------+
| id | | id | | id |
| name | | boy_id | | name |
| birth | | girl_id | | birth |
+-------+ | start_dating | +-------+
+--------------|
START_DATING is type of TIMESTAMP or DATE
I have two beans Boy and Girl with many-to-many relation
#ManyToMany(fetch = FetchType.LAZY)
#JoinTable(name = "BOY_GIRL", joinColumns = {#JoinColumn(name = "BOY_ID")}, inverseJoinColumns = {#JoinColumn(name = "GIRL_ID")})
public Set<Girl> getGirls() {
return girls;
}
Now, how can I do select query with HQL, if I want to get the list girls with condition:
where boy_id = (some_boy_id) and START_DATING > (some_timestamp)
I think you have to create a BoyGirl class because table BOY_GIRL is not a simple many-to-many table (If it is, then the columns are has to be only boy_id and girl_id). So what you should do is create the BoyGirl class then map BOY to BOY_GIRL with one-to-many and also map GIRL to BOY_GIRL with one-to-many
table relations
+-------+ +--------------+ +-------+
| BOY | | BOY_GIRL | | GIRL |
+-------+ +--------------| +-------+
| id | 0..* --- 1..1 | id | 1..1 --- 0..* | id |
| name | | boy_id | | name |
| birth | | girl_id | | birth |
+-------+ | start_dating | +-------+
+--------------+
java classes
public class BoyGirl {
private long id;
private Boy boy;
private Girl girl;
private Date startDating;
}
public class Boy {
//other attributes omitted
private Set<BoyGirl> boyGirls;
}
public class Girl {
//other attributes omitted
private Set<BoyGirl> boyGirls;
}
The select query you need
// I'm using criteria here, but it will have the same result as your HQL
public List getGirls(Boy boy, Date startDating) {
Criteria c = sessionFactory.getCurrentSession().createCriteria(BoyGirl.class);
c.add(Restrictions.eq("boy.id", boy.getId());
c.add(Restrictions.lt("startDating", startDating);
List<BoyGirl> boyGirls = (List<BoyGirl>) c.list();
// at this point you have lazily fetch girl attributes
// if you need the girl attributes to be initialized uncomment line below
// for (BoyGirl boyGirl : boyGirls) Hibernate.initialize(boyGirl.getGirl());
return boyGirls;
}
I think your entity model is not correct, you need a third entity representing the relationship attribute and you should map both Boy and Girl as many to one to that entity.
Otherwise there is no way to specify the relationship attribute, in your case starting_date, as a condition in a query.
Look at this link, you can find a detailed explanation on how to map a join table with additional attributes.
As the intermediate table BOY_GIRL has some additional attributes (start_dating) you need to create another intermediate entity in your domain model for it, eg:
#Table(name="BOY_GIRL")
class Relationship {
#Id
long id;
#ManyToOne
Boy boy;
#ManyToOne;
Girl girl;
#Column
Date startDating;
}
I don't think its great to keep the dating information directly inside the join table (since the purpose of this should simply be to associate a boy and a girl).
However, if you really want to keep your current structure, and solve it with HQL, you should be able to do something like
SELECT g FROM GIRL g, BOY_GIRL bg
WHERE bg.start_dating = :revelantdate
AND bg.boy_id = :boyid
AND g.id = bg.girl_id

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