I have a problem with NullHandling in Spring Data. I am trying to pass custom NullHandling to my findAll method of repository - something like below:
Page<Developer> developerPage = developerRepository.findAll(
new PageRequest(0, 2, new Sort(new Sort.Order(Sort.Direction.ASC, "user").nullsFirst()))
);
However, I have option show-sql set to true and in logs I see that in query which is passed to the database there is nothing mention about null handling. I get wrong results (even more different results for Postgres and H2 but I understand it is the difference between default null handling for each database). Configuration for Postgres is:
spring.datasource.driverClassName=org.postgresql.Driver
spring.datasource.url=jdbc:postgresql://localhost/postgres?useUnicode=yes&characterEncoding=UTF-8
spring.datasource.username=postgres
spring.jpa.hibernate.ddl-auto=create-drop
spring.jpa.properties.hibernate.globally_quoted_identifiers=true
spring.jpa.show-sql=true
spring.jpa.database-platform=org.hibernate.dialect.PostgreSQLDialect
What is the problem here? Is custom null handling supported in Spring Data JPA?
Edit:
I found out that query order part for JPA is created in QueryUtils class in method toOrders(..). What is interesting - Sort implementation from spring data is mapped to Sort implementation of JPA where there is no support for null handling. There is also a jira issue that describes that it is not supported but it is from 2014: https://jira.spring.io/browse/DATACMNS-491
you can use this property in app.yml
spring.jpa.hibernate.order_by.default_null_ordering: last
Related
I have an Spring REST Api and a MySQL Database, now I would like to expose the result of an custom query with multiple joins.
I have tried multiple suggestions that I found online but none of them were working for me so far.
What I want to do is something like a read only DTO that has all the fields of my custom query so that in the end I have one api page exposing the DTO data as JSON so my client (Angular) can read the data from there.
I already tried to:
create an #RestController with an injected EntityManager that executes a NativeQuery and then populates the DTO with the returned data but since my DTO is no Entity I get an Hibernate Mapping Exception
create a custom Repository and its Impl but with a similar outcome
place the Query inside an existing #Entity that is part of the Query statement
What am I missing here? Do I have to annotate my DTO maybe? Cuttently it's just a POJO, I think the #Entity annotation is not the right thing here since I don't want a Table created from my DTO.
Fixed it by letting the Query return an Array of type Object and afterwards mapping it to the DTO Constructor.
I am using spring boot, spring data JPA, I am searching for solution to get all column names of a given table. But could not found as per my requirements
Not want a solution with native query.Looking for general solution using spring data abstraction.
I am able to get the column names using normal java but i want to fetch them using spring data JPA.
they are several ways
public interface TableMetadataRepository extends JpaRepository<TableMetadata, TableMetadataKey>
{
TableMetadata findByTableName(String tableName);
}
then you can go for
List<TableMetadata> metadata = tableMetadataRepository.findAll()
TableMetadata metadataofspecifictable = tableMetadataRepository.findByTableName("urtable");
I want to make userName property in User node as a unique.
I used below code but it doesn't create a unique constraint in the Neo4j database.
#Property(name = "name")
#Index(unique = true)
private String usreName;
FYI, I'm using the Neo4j Server version: 3.3.6 (community) With Spring Boot 2.
but if I create a constraint in the Neo4j Browser by myself, it works.
CREATE CONSTRAINT ON (user:User) ASSERT user.userName IS UNIQUE
Is there a way to force Spring Data Neo4J to create unique properties, without creating them by myself in Database?
You need to configure the auto index manager if you want the application code create the constraints.
You can find the best fitting option in the documentation:
https://docs.spring.io/spring-data/neo4j/docs/current/reference/html/#reference:indexing:creation
Just a note on this topic: Think about the auto index creation like Hibernate's DDL support. It is a helper at development time. You should not use assert and update in production environments but only validate.
Reason
In Spring Data Neo4j 4, index management concerns were removed from
the mapping framework entirely.
(from Index Management in Spring Data Neo4j)
Solution
#Autowired
private SessionFactory sessionFactory;
#PostConstruct
public void createIndexesAndConstraints() {
Session session = sessionFactory.openSession();
Result result = session.query("CREATE INDEX ON :User(userName)", Collections.EMPTY_MAP);
}
You can configure the mode our auto index manager works in through application.properties
spring.data.neo4j.auto-index=validate # or
# spring.data.neo4j.auto-index=update
# spring.data.neo4j.auto-index=assert
Default mode is none. Apart from that, what #meistermeier says applies.
Also, Neo4jOperations was deprecated in SDN 4 something and has been removed in SDN 5. Use Session instead for operations "near" the database.
Thank you #ThirstForKnowledg for your answer. But I have 3 other Questions:
1- I'm using Spring Boot 2, and I can not see Neo4jOperations in my classpath to import it.
2- Should I put this in my Entity node or in another bean?
3- What about after running my application two or more times? I think it would cause an exception for the second time or more.
I have a requirement to set a date_updated value in my database for each row when that row is updated. Let's call the entity that I'm working with Order, which has a corresponding orders table in the database.
I've added the date_updated column to the orders table. So far, so good.
The #Entity Order object that I'm working with is provided by a third party. I do not have the ability to modify the source code to add a field called dateUpdated. I have no requirement to map this value to the object anyway - the value is going to be used for business intelligence purposes only and does not need to be represented in the Java entity object.
My problem is this: I want to update the date_updated column in the database to the current time each time an Order object (and its corresponding database table row) is modified.
Constraints:
We are using Oracle, Spring, JPA and Hibernate
I cannot use Oracle triggers to update the value. We are using a database replication technology that prevents us from using triggers.
My approach thus far has been to use a JPA EntityListener, defined in xml, similar to this:
<entity-mappings xmlns="....">
<entity class="com.theirs.OrderImpl">
<entity-listeners>
<entity-listener class="com.mine.listener.OrderJPAListener" />
</entity-listeners>
</entity>
</entity-mappings>
My listener class looks like this:
public class OrderJPAListener {
#PostPersist
#PostUpdate
public void recordDateUpdated(Order order) {
// do the update here
}
}
The problem I'm having is injecting any sort of persistence support (or anything at all, really) into my listener. Because JPA loads the listener via its methods, I do not have access to any Spring beans in my listener class.
How do I go about injecting an EntityManager (or any Spring bean) into my listener class so that I can execute a named query to update the date_updated field?
How do I go about injecting an EntityManager (or any Spring bean) into
my listener class so that I can execute a named query to update the
date_updated field?
As noted above JPA 2.1 supports injecting managed beans to an Entity Listener via CDI. Whether or not Spring supports this I am not sure. The folloiwng post proposes a Spring specific solution.
https://guylabs.ch/2014/02/22/autowiring-pring-beans-in-hibernate-jpa-entity-listeners/
A possible alternative approach would be however to override the SQL generated by Hibernate on an update which is possible as detailed below.
https://docs.jboss.org/hibernate/orm/3.6/reference/en-US/html/querysql.html#querysql-cud
This would be straightforward if you had the source as you would just need to add the #SQLUpdate annotation and tag on the additional date_update column. As you don't however you would need to look at redefining the metadata for that Entity via an xml configuration file and defining the sql-update statement as outlined above:
https://docs.jboss.org/hibernate/stable/annotations/reference/en/html/xml-overriding.html#xml-overriding-principles-entity
Since JPA 2.1 Entity Listeners are CDI managed. Have you tried using #PersistenceUnit annotation? Are you using JTA transaction type?
Otherwise you could use Persistence.createEntityManagerFactory within the Listener class to retrieve the Persistence Context.
I have a set of Entities generated using Spring ROO. After several commands, basically using web mvc, I have a set of links to get the contents from a database. I need to order the contents according to title, instead of the order in the table. How can I do it? Is there any Spring ROO commando or annotation to order the items.
For more information, I am using Spring Roo 1.2.1, and the finder I got is the following.
public static List<Deporte> Deporte.findAllDeportes() {
return entityManager().createQuery("SELECT o FROM Deporte o", Deporte.class).getResultList();
}
Thanks in advance.
Spring Roo uses JPA for the persistence. Search for JPA tutorials and documentation to find what you're looking for.
JPQL uses the order by clause to order results returned by a query. This order by is very similar to the SQL order by clause:
SELECT o FROM Deporte o order by o.title