I recently replaced PostgreSql unit test database with an in memory H2 Database. I couldn't figure out why couple tests are failing, it was working fine with Postgre. There are approx. 280+ unit tests in this application. The failing dao tests are selecting from a view and the entity has a EmbeddedId, those the columns of that view.
See below code (Note: I changed names, code and the sql to hide the real names when writing this email, but this was a working unit test with Postgre db)
<pre>
#Table(name = "item_view") // <- item_view is a database view
public class ItemV implements Serializable
{
.....
#EmbeddedId // <- entity has an embedded id
private ItemVId id;
.....
#Embeddable
public static class ItemVId implements Serializable //<- This is the embeddedId
{
#Column(name = "item_id", updatable=false, insertable=false)
private Long ItemId; //<- col no.1 of view
#Column(name = "item_type_id", updatable=false, insertable=false)
private Integer ItemTypeId; //<- col no.2 of view
.....
ItemType is an enum
And the view is
CREATE OR REPLACE VIEW item_view AS
( ( ( SELECT pt.id as item_id, cit.id as item_type_id
FROM xyz pt, item_type cit
WHERE pt.name::text = 'xyz'::text
UNION
SELECT z.id as item_id, cit.id as item_type_id
FROM zzz z, item_type cit
WHERE z.name::text = 'zzz'::text)
..............
and the dao method is
public ItemView find(Long itemId, ItemType itemType)
{
String hql = " from ItemV iv where iv.id.itemId = :itemId and iv.id.itemTypeId = :itemTypeId ");
List<ItemView> result = (List<ItemView>)getEntityManager()
.createQuery(hql)
.setParameter("itemId", itemId)
.setParameter("itemTypeId", itemType.getId())
.setMaxResults(1)
.getResultList();
return result.isEmpty()
? null : result.get(0);
}
This dao method always returns empty results, never finding existing rows in the view??? I know those rows exist because when I do getAll() on the same dao I see results and I see a matching row for the criteria.
Is there anything special about selecting rows from a view in H2 database?
Thanks
Ok fixed, I had to use a smaller number for LOCK_TIMEOUT value, so now I can connect to database and see values. Selecting from view problem also fixed.
I have to say H2 is really neat and elegant. I'm glad, I switched the unit test db to H2.
Related
i'm using Spring Boot 2.4.2 and Data module for JPA implementation.
Now, i'm using an Oracle View, mapped by this JPA Entity:
#Entity
#Immutable
#Table(name = "ORDER_EXPORT_V")
#ToString
#Data
#NoArgsConstructor
#EqualsAndHashCode(onlyExplicitlyIncluded = true)
public class OrderExportView implements Serializable {
private static final long serialVersionUID = -4417678438840201704L;
#Id
#Column(name = "ID", nullable = false)
#EqualsAndHashCode.Include
private Long id;
....
The view uses an UNION which allows me to obtain two different attributes of the same parent entity, so for one same parent entity (A) with this UNION I get the attribute B in row 1 and attribute C in row 2: this means that the rows will be different from each other.
If I run the query with an Oracle client, I get the result set I expect: same parent entity with 2 different rows containing the different attributes.
Now the issue: when I run the query with Spring Data (JPA), I get the wrong result set: two lines but duplicate.
In debug, I check the query that perform Spring Data and it's correct; if I run the same query, the result set is correct, but from Java/Spring Data not. Why??
Thanks for your support!
I got it! I was wrong in the ID field.
The two rows have the same parent id, which is not good for JPA, which instead expects a unique value for each line.
So, now I introduced a UUID field into the view:
sys_guid() AS uuid
and in JPA Entity:
#Id
#Column(name = "UUID", nullable = false)
#EqualsAndHashCode.Include
private UUID uuid;
#Column(name = "ID")
private Long id;
and now everything works fine, as the new field has a unique value for each row.
I am beginner in spring. I want to show SQL data to JSP view page.
This is my SQL table
create table customer(
id int primary key,
name varchar(250),
salary int,
manager_id int
)
and I am trying to show data from this query
select m.id, m.name, m.salary, n.name from customer m, customer n where n.id=m.manager_id
So basically from this query, I am trying to show ID int, name varchar, salary int, manager_name varchar.
I have create the entity java class as below
#Entity
#Table(name="customer")
public class Customer{
#Id
#GeneratedValue(strategy = GenerationType.IDENTITY)
#Column
private int id;
#Column
private String name;
#Column(name="manager_id")
private String manager;
#Column(name="salary")
private int salary;
............
............
}
This is the code of my DAO class
Session session= entityManager.unwrap(Session.class);
Query<Employee> query= session.createQuery(<above sql query need to add here?>,Customer.class);
return query.getResultList();
So the issues are,
This SQL query return the data which could not be matched to Customer Entity class. So do I need to create another Entity class for this? Is there any better way?
The above required SQL query is not able to execute. What the correct way to execute custom SQL query?
Regarding your first question: Yes there is better way. you can directly fetch the results in a projection dto class. take a at: https://vladmihalcea.com/the-best-way-to-map-a-projection-query-to-a-dto-with-jpa-and-hibernate/
About your second question: What Do you mean by saying the query does not execute?
Can you give us the Exception/Stacktrace? Did you try to execute the query (sql form of it) physically? Does it run then?
Lets tell I have two tables.
CREATE TABLE user (ID int AUTO_INCREMENT,PRIMARY KEY (ID));
CREATE TABLE points (ID int AUTO_INCREMENT, user_id int, points int,PRIMARY KEY (ID));
How can I use spring-boot jpa to request user and max points like this?
select u.ID,max(p.points) from user u, points p where u.id=p.user_id
Or any alternatives to solve this kind of problems?
Assuming you have a Repository of User:
public class User {
private int id;
private List<Point> points;
...
}
With a relationship to the Points object:
public class Point {
private int id;
private User User;
private int points;
...
}
I haven't tested, but you should be able to do:
User findFirstByIdOrderByPointPointsDesc(int userId)
Similar to example 18 in the docs.
The only problem you have, regardless of the query or Spring Data, is if you have two users with the same point values. If you need more logic around tie-breaking, it might be more worth it to write a #Query (with your query, plus the extra tie-breaking logic) or a #NativeQuery.
I usually create a class to hold result such as
public class Result {
private User user;
private int votes;
// getters and setters
}
And write a custom query in the repository to fetch the data
#Query(value = "SELECT new com.package.Result (u, MAX (p.points) )
FROM user u
JOIN points p
ON u.id = p.user_id
GROUP BY u")
List<Result> getPointsPerUser();
Replace com.package.Result with appropriate path to the Result class.
Below method can be written in Repo and used as Transaction as in dao layer, which will be accessible from service layer.
#Query(value = "SELECT max(transactionId) FROM TransactionPayloadInfo")
int getMaxTransactionId();
create a model of data.
public class Data {
private int id;
private int maxPoints;
// getters and setters method
}
And write your query like this for getting model of Data.
#Query(select packagename.Data(u.ID,max(p.points) ) from user u, points p where u.id=p.user_id)
Data findUserWithMaxVots();
I am trying to run a native query on a repository method so that it returns the results with some counts. It was too complicated to do with JPQL, so I opted for a native query instead.
Repository
#RepositoryRestResource(collectionResourceRel="projects", path="projects")
interface ProjectRepository extends BaseRepository<Project, Long>, ProjectRepositoryCustom {
#Query(
value="SELECT p.id, p.user_id, p.title, p.description, p.created_on, p.version,(SELECT COUNT(0) FROM projectparts WHERE project_id = p.id) AS parts,(SELECT COUNT(0) FROM requests WHERE project_id = p.id) AS requests FROM projects AS p ORDER BY ?#{#pageable}",
countQuery="SELECT COUNT(0) FROM projects",
nativeQuery=true
)
Page<Project> findAll(Pageable pageable)
}
The entity has 2 properties annotated with #Transient so that the info is not persisted to the database. All the data comes back fine except the 2 transient properties which return null for the values. When I copy the query from the console and paste it in MySQL Workbench, the results are as expected and I see the counts that I need. Anyhow, not sure if there is anything else that needs to be done in order to get this native query to work as an annotation. I hard coded a value in the sub-query SELECT 55 FROM... just to see if it was a problem with the count and it still returned as null. I ran the query in Workbench and it works fine.
I've tried changing the transient property type from Integer, Long, BigInteger, long, int... and none of that made a difference. Since I'm using Groovy, I also tried def to let Groovy infer the type and that didn't work either.
I also tried running the project from the terminal instead and it still didn't work. I've tried it on a Mac and Linux and had no luck with displaying the results of the counts.
This will not work. You could use an SQLConstructorExpression however the returned instances would be unmanaged which is a major drawback.
An better option is to create a simple DB view which holds the pieces of summary info for the Project. You can them map the Project entity to both it's table and the associated summary view using the #SecondaryTable functionality of JPA.
https://en.wikibooks.org/wiki/Java_Persistence/Tables#Example_mapping_annotations_for_an_entity_with_multiple_tables
An added benefit is that you can sort and query on the summary values as for any other property.
Updated mapping:
#Entity
#Table(name = "projects")
#SecondaryTable(name = "projects_summary_vw")
public class Project{
//use Integer rather than int to avoid issue outlined here:
//http://stackoverflow.com/a/37160701/1356423
#Column(name = "parts", table = "projects_summary_vw",
insertable="false", updateable="false")
private Integer partsCount;
#Column(name = "requests", table = "requestsCount"
insertable="false", updateable="false")
private Integer requestsCount;
//other mappings as required
}
No Custom query required:
#RepositoryRestResource(collectionResourceRel="projects",
path="projects")
interface ProjectRepository extends BaseRepository<Project, Long>,
ProjectRepositoryCustom {
}
An alternative non-JPA compliant solution may be to use some vendor specific extension rather than a view. Hibernate for example has an #Formula annotation which could be used:
https://docs.jboss.org/hibernate/orm/5.1/javadocs/org/hibernate/annotations/Formula.html
#Entity
#Table(name = "projects")
public class Project{
#Formula("my count query as native sql")
private Integer partsCount;
#Formula("my count query as native sql")
private Integer requestsCount;
//other mappings as required
}
I am implementing queries in my web application with JPA repositories. The two main tables I am querying from are FmReportTb and SpecimenTb.
Here are the two entity classes (only important attributes are listed).
//FmReportTb.java
#Entity
#Table(name="FM_REPORT_TB")
public class FmReportTb implements Serializable {
#Column(name="ROW_ID")
private long rowId;
#Column(name="FR_BLOCK_ID")
private String frBlockId;
#Column(name="FR_FULL_NAME")
private String frFullName;
#OneToOne
#JoinColumn(name="SPECIMEN_ID")
private SpecimenTb specimenTb;
FmReportTb has OneToOne relationship with SpecimenTb.
#Entity
#Table(name="SPECIMEN_TB")
public class SpecimenTb implements Serializable {
private String mrn;
#OneToOne(mappedBy="specimenTb", cascade=CascadeType.ALL)
private FmReportTb fmReportTb;
The query I am working on is to find all records in FmReportTb and show a few attributes from FmReportTb plus mrn from SpecimenTb.
Here is my JPA repository for FmReportTb:
#Repository
public interface FmReportRepository extends JpaRepository<FmReportTb, Long> {
#Query("select f from FmReportTb f where f.deleteTs is not null")
public List<FmReportTb> findAllFmReports();
Since, I am only showing part of the attributes from FmReportTb and one attribute from SpecimenTb, I decided to create a Value Object for FmReportTb. The constructor of the VO class assigns attributes from FmReportTb and grabs mrn attribute from SpecimenTb based on the OneToOne relationship. Another reason for using VO is because table FmReportTb has a lot of OneToMany children entities. For this particular query, I don't need any of them.
public class FmReportVO {
private String frBlockId;
private Date frCollectionDate;
private String frCopiedPhysician;
private String frDiagnosis;
private String frFacilityName;
private String frFullName;
private String frReportId;
private String filepath;
private String mrn;
public FmReportVO(FmReportTb fmReport) {
this.frBlockId = fmReport.getFrBlockId();
this.frCollectionDate = fmReport.getFrCollectionDate();
this.frCopiedPhysician = fmReport.getFrCopiedPhysician();
this.frDiagnosis = fmReport.getFrDiagnosis();
this.frFacilityName = fmReport.getFrFacilityName();
this.frFullName = fmReport.getFrFullName();
this.frReportId = fmReport.getFrReportId();
this.mrn = fmReport.getSpecimenTb().getMrn();
}
I implemented findall method in servicebean class to return a list of FmReportTb VOs.
//FmReportServiceBean.java
#Override
public List<FmReportVO> findAllFmReports() {
List<FmReportTb> reports = fmReportRepository.findAllFmReports();
if (reports == null) {
return null;
}
List<FmReportVO> fmReports = new ArrayList<FmReportVO>();
for (FmReportTb report : reports) {
FmReportVO reportVo = new FmReportVO(report);
String filepath = fileLoadRepository.findUriByFileLoadId(report.getFileLoadId().longValue());
reportVo.setFilepath(filepath);
fmReports.add(reportVo);
}
return fmReports;
}
Lastly, my controller looks like this:
#RequestMapping(
value = "/ristore/foundation/",
method = RequestMethod.GET,
produces = "application/json")
public ResponseEntity<List<FmReportVO>> getAllFmReports() {
List<FmReportVO> reports = ristoreService.findAllFmReports();
if (reports == null) {
return new ResponseEntity<List<FmReportVO>>(HttpStatus.NOT_FOUND);
}
return new ResponseEntity<List<FmReportVO>>(reports, HttpStatus.OK);
}
There are about 200 records in the database. Surprisingly, it took almost 2 full seconds to retrieve all the records in JSON. Even though I did not index all the tables, this is way too slow. Similar query takes about probably a few ms on the database directly. Is it because I am using Value Objects or JPA query tends to be this slow?
EDIT 1
This may have to do with the fact that FmReportTb has almost 20 OneToMany entities. Although the fetchmode of these child entities are set to LAZY, JPA Data repository tends to ignore the fetchmode. So I ended up using NamedEntityGraph to specify the attributes EAGER. This next section is added to the head of my FmReportTb entity class.
#Entity
#NamedEntityGraph(
name = "FmReportGraph",
attributeNodes = {
#NamedAttributeNode("fileLoadId"),
#NamedAttributeNode("frBlockId"),
#NamedAttributeNode("frCollectionDate"),
#NamedAttributeNode("frDiagnosis"),
#NamedAttributeNode("frFullName"),
#NamedAttributeNode("frReportId"),
#NamedAttributeNode("specimenTb")})
#Table(name="FM_REPORT_TB")
And then #EntityGraph("FmReportGraph") was added before the JPA repository query to find all records. After doing that, the performance is improved a little bit. Now fetching 1500 records only takes about 10 seconds. However, it still seems too slow given each json object is fairly small.
Answering for the benefit of others with slow JPA queries...
As #Ken Bekov hints in the comments, foreign keys can help a lot with JPA.
I had a couple of tables with a many to one relationship - a query of 100,000 records was taking hours to perform. Without any code changes I reduced this to seconds just by adding a foreign key.
In phpMyAdmin you do this by creating a Relationship from the "many" table to the "one" table. For a detailed explanation see this question: Setting up foreign keys in phpMyAdmin?
and the answer by #Devsi Odedra