GORM is the data access technology offered by Grails, and one of its spin-offs. This talk covers the 6 most important new features of GORM 6: GORM without Grails and without Spring. Multi-tenancy. RxGORM. Multiple datasource support. Unit testing. Data Services.

1. 6 things you need to
know about GORM 6
Álvaro Sánchez-Mariscal
@alvaro_sanchez

2. About me
— Coming from Madrid
!
— Developer since 2001 (Java / Spring stack).
— Grails fanboy since v0.4.
— Working @ OCI since 2015: Groovy, Grails & Micronaut!
— Father since 2017!
"
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3. 1. GORM without Grails /
Spring Boot / Micronaut
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4. build.gradle
dependencies {
compile 'org.codehaus.groovy:groovy:2.5.0'
compile "org.grails:grails-datastore-gorm-hibernate5:6.1.9.RELEASE"
compile 'org.hibernate:hibernate-validator:6.0.2.Final'
compileOnly 'org.glassfish.web:el-impl:2.2.1-b05'
runtime 'org.glassfish:javax.el:3.0.1-b08'
runtime "com.h2database:h2:1.4.192"
runtime "org.apache.tomcat:tomcat-jdbc:8.5.0"
runtime "org.apache.tomcat.embed:tomcat-embed-logging-log4j:8.5.0"
runtime "org.slf4j:slf4j-api:1.7.10"
runtime "ch.qos.logback:logback-classic:1.2.3"
testCompile "org.spockframework:spock-core:1.1-groovy-2.4"
}
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5. 2. Data Services
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6. Data Services
Auto-generated persistence logic from interfaces and
abstract classes
@Service(Book)
interface BookService {
Book getBook(Serializable id)
}
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7. Advantages
— Type safety.
— Signatures statically compiled.
— Testing
— Since they are interfaces, can be easily tested with
Spock mocks.
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8. Advantages
— Performance.
— No runtime proxies, eveything is compile-time.
— Transaction management.
— Methods are wrapped in a transaction (read-only
for read operations).
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9. Abstract classes support
@Service(Book)
abstract class BookService {
abstract Book getBook(Serializable id)
abstract Author getAuthor(Serializable id)
Book updateBook(Serializable id, Serializable authorId) {
Book book = getBook(id)
if(book != null) {
Author author = getAuthor(authorId)
if(author == null) throw new IllegalArgumentException("Author does not exist")
book.author = author
book.save()
}
return book
}
}
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10. Pagination support
Data service:
@Service(Book)
interface BookService {
List<Book> findBooks(String title, Map args)
}
Usage:
List<Book> books = bookService.findBooks(
"The Stand",
[offset:10, max:10, sort:'title', order:'desc']
)
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11. "Dynamic finder"-like queries
Just that they are statically compiled!
@Service(Book)
interface BookService {
List<Book> findByTitleAndPublishDateGreaterThan(String title, Date publishDate)
}
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12. Where queries
@Service(Book)
interface BookService {
@Where({ title ==~ pattern && releaseDate > fromDate })
Book searchBooks(String pattern, Date fromDate)
}
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13. Query joins
@Service(Book)
interface BookService {
@Join('author')
Book find(String title)
@Join(value='author', type=LEFT)
Book findAnother(String title)
}
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14. HQL queries
@Service(Book)
interface BookService {
@Query("from ${Book book} where ${book.title} like $pattern")
Book searchByTitle(String pattern)
}
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15. Projections
@Service(Book)
interface BookService {
Date findBookReleaseDate(String title)
List<Date> findBookReleaseDate(String publisher)
@Query("select $b.releaseDate from ${Book b} where $b.publisher = $publisher order by $b.releaseDate")
List<Date> findBookReleaseDatesHql(String publisher)
}
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16. 3. Unit testing
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17. Unit testing
class ClubSpec extends Specification {
@Shared @AutoCleanup HibernateDatastore hibernateDatastore
void setupSpec() { hibernateDatastore = new HibernateDatastore(Club) }
@Rollback
void "it can persist clubs"() {
when:
new Club(name: "Real Madrid").save(flush: true)
then:
Club.count() == old(Club.count()) + 1
}
}
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18. 4. Multiple datasources
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19. application.yml
dataSource:
dbCreate: create-drop
url: "jdbc:h2:mem:laliga"
dataSources:
premier:
dbCreate: create-drop
url: "jdbc:h2:mem:premier"
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20. Domain class
class Club {
static mapping = {
datasource ConnectionSource.ALL
}
String name
String stadium
}
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21. Data source namespace
Club.premier.findByName("Liverpool")
//...
Club rma = new Club(name: "Real Madrid")
club.save() // Default data source
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22. 5. Multi-Tenancy
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23. Modes
— DATABASE: a separate database with a separate
connection pool is used to store each tenants data.
— SCHEMA: the same database, but different schemas are
used to store each tenants data.
— DISCRIMINATOR - The same database is used with a
discriminator used to partition and isolate data.
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24. AST Transformations
— @CurrentTenant: resolve the current tenant for the
context of a class or method.
— @Tenant: use a specific tenant for the context of a
class or method
— @WithoutTenant: execute logic without a specific
tenant (using the default connection)
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25. AST Transformations
@CurrentTenant // resolve the current tenant for every method
class TeamService {
@WithoutTenant // execute the countPlayers method without a tenant id
int countPlayers() {
Player.count()
}
@Tenant({"another"}) // use the tenant id "another" for all GORM logic within the method
List<Team> allTwoTeams() {
Team.list()
}
List<Team> listTeams() {
Team.list(max:10)
}
@Transactional
void addTeam(String name) {
new Team(name:name).save(flush:true)
}
}
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26. Configuration
grails:
gorm:
multiTenancy:
mode: DATABASE
tenantResolverClass: org.grails.datastore.mapping.multitenancy.web.SubDomainTenantResolver
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27. Domain classes
class Book implements MultiTenant<Book> {
String title
}
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28. Querying
List<Book> books = withCurrent {
Book.list()
}
//...
List<Book> books = withId("otherTenant") {
Book.list()
}
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29. 6. RxGORM
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30. Domain class
class Club implements RxMongoEntity<Club> {
ObjectId id
String name
String stadium
}
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31. GORM operations
new Book(title:"The Stand")
.save() // Returns an rx.Observable<Book>
.subscribe { Book it ->
// If you don't subscribe, it won't be executed
println "ID = ${book.id}"
}
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32. Q & A
Álvaro Sánchez-Mariscal
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