Download - Advanced GORM - Beyond Relational

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Advanced GORM - Beyond RelationalBy Graeme Rocher

Agenda

§ Understanding GORM Internals § GORM Standalone § Tips and Tricks § Jumping into MongoDB § Unit testing with GORM § Summary / Q & A

GORM

• Powerful multi-datastore query layer

• Dynamic finders, criteria, and persistence methods

• Integrated validation • Automatic mapping of entities

to underlying datastore • Easy access to native APIs

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Understanding what makes GORM tick

GORM Internals

Grails Data Mapping Project

• https://github.com/grails/grails-data-mapping

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https://github.com/grails/grails-data-mapping

Built by Travis

• https://travis-ci.org/grails/grails-data-mapping

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https://travis-ci.org/grails/grails-data-mapping

Developer Documentation

• http://grails.github.com/grails-data-mapping/

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http://grails.github.com/grails-data-mapping/

Important Subprojects• grails-datastore-core

– Core low level API

• grails-datastore-gorm– GORM API layer

• grails-datastore-gorm-tck– Test Suite

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Demo: Code Walkthrough

Contribute to GORM

• GORM is huge and sprawling • Covers loads of data stores • Great area to contribute to the

community. Some ideas: • Multi Tenancy • Elastic Search • Hadoop / HBase

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Use GORM outside of Grails

GORM Standalone

What is GORM Standalone?• Easy initialisation of GORM outside of Grails • And a set of Spring Boot plugins • Required modularisation of codebase • Reduction of external dependencies • Simplification of GORM setup

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Standalone Entities• Annotated with grails.persistence.Entity

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@Entity class Person { String name static constraints = { name blank:false } }

GORM for Hibernate Standalone• https://gist.github.com/graemerocher/c25ec929d9bcd1adcbea

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@Grab("org.grails:grails-‐datastore-‐gorm-‐hibernate4:3.1.2.RELEASE") @Grab("com.h2database:h2:1.3.164")

import grails.orm.bootstrap.*

init = new HibernateDatastoreSpringInitializer(Person) def dataSource = new DriverManagerDataSource(Driver.name, "jdbc:h2:prodDb;MVCC=TRUE;LOCK_TIMEOUT=10000;DB_CLOSE_ON_EXIT=FALSE", 'sa', '') init.configureForDataSource(dataSource)

https://gist.github.com/graemerocher/c25ec929d9bcd1adcbea

GORM for MongoDB Standalone• https://gist.github.com/graemerocher/9683650

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@Grab("org.grails:grails-‐datastore-‐gorm-‐mongodb:3.0.2.RELEASE")

import grails.mongodb.bootstrap.*

init = new MongoDbDataStoreSpringInitializer(Person) init.configure()

https://gist.github.com/graemerocher/9683650


Demo: GORM Standalone

GORM for Hibernate in Spring Boot• Add gorm-hibernate4-spring-boot as a dependency

• Then add persistent entities that are annotated with grails.persistence.Entity

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compile "org.grails:gorm-‐hibernate4-‐spring-‐boot:1.0.0.RELEASE"

GORM for MongoDB in Spring Boot• Add gorm-mongodb-spring-boot as a dependency

• Then add persistent entities that are annotated with grails.persistence.Entity

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compile "org.grails:gorm-‐mongodb-‐spring-‐boot:1.1.0.RELEASE"


Take GORM to the next level

Tips & Tricks

GORM Tips & Tricks• Understanding where queries • Working with DetachedCriteria • Using formula and column readers / writers • Going asynchronous

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Where Queries• Type-safe, composable query API

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DetachedCriteria<Person> query = Person.where { lastName == "Simpson" }

def results = query.list()


Demo: Where Queries

Hibernate Subqueries• Perform nested “in” or “notIn” sub queries that span domain

classes using where queries:

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def employees = Employee.where { region.continent in ['APAC', "EMEA"] }.id()

def results = Sale.where { employee in employees && total > 50000 }.employee.list()

Hibernate Correlated Subqueries• Declare aliases using “def” for cross query references:

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def query = Employee.where { def em1 = Employee exists Sale.where { def s1 = Sale def em2 = employee return em2.id == em1.id }.id() } def results = query.list()

Hibernate Column Formula• A column can be a read-only formula

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class Product { Float price Float taxRate Float tax static mapping = { tax formula: 'PRICE * TAX_RATE' } }

Hibernate Column Readers/Writers• New in 2.4: Implement custom column readers and writers

to transform data when written or read from the database.

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class Name { String title static mapping = { title write:'UPPER(?)', read:'REPEAT(title, 2)' } }

Asynchronous GORM• Database operations are blocking • Can be helpful to isolate these blocking operations on a

separately managed thread • Work underway in some NoSQL datastore on fully

asynchronous drivers (MongoDB, CouchDB etc.) • No usable asynchronous SQL/JDBC drivers on the horizon

(to my knowledge)

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Async Namespace• Any GORM method can become Async

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import static grails.async.Promises.*

def p1 = Person.async.get(1L) def p2 = Person.async.get(2L) def p3 = Person.async.get(3L) def results = waitAll(p1, p2, p3)


Demo: Async GORM

Async Tasks• Individual async method calls often too fine grained, use

task method to implement Async GORM tasks

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def promise = Person.async.task { withTransaction { def person = findByFirstName("Homer") person.firstName = "Bart" person.save(flush:true) } } Person updatedPerson = promise.get()


Go schemaless!

Jumping into MongoDB

GORM for MongoDB• Geospacial querying • GeoJSON models • Full text search • Schemaless domain models • Projections via MongoDB

aggregation • Stateless and Stateful modes • Custom user types

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GORM for MongoDB Internals• MongoEntityPersister implements persistence • MongoQuery implements querying aggregation • MongoSession implements batch inserts, updates and

deletes • MongoGormStaticApi adds extra GORM methods • GeoJSONType and subclasses implement GeoJSON

custom types • https://github.com/grails/grails-data-mapping/tree/master/

grails-datastore-gorm-mongodb33

https://github.com/grails/grails-data-mapping/tree/master/grails-datastore-gorm-mongodb

GORM, MongoDB & GeoJSON• Geo Data in MongoDB represented by GeoJSON types

– http://geojson.org • Package grails.mongodb.geo contains GeoJSON

types – Point, Polygon, LineString, MultiPoint, MultiLineString, MultiPolygon, GeometryCollection

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http://geojson.org

Geospacial Querying

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def point = new Point(2, 1) def p = new Place(point: point)

def poly1 = Polygon .valueOf([ [0.0, 0.0], [3.0, 0.0], [3.0, 3.0], [0.0, 3.0], [0.0, 0.0] ])

Place.findByPointGeoWithin(poly1)

MongoDB Text Search• Create text indices and use methods

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Product.search('"Coffee Cake"') .size() == 1 Product.searchTop("cake").size() == 4 Product.searchTop("cake",3).size() == 3 Product.countHits('coffee') == 5

Schemaless Dynamic Properties• Add dynamic properties with the subscript operator

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def p = new Plant(name:"Pineapple") p.save() p["color"] = "Yellow" p["hasLeaves"] = true


Demo: GORM for MongoDB

Other Implementations• Neo4j

– http://grails.org/plugin/neo4j • Redis GORM

– http://grails.org/plugin/redis-gorm • GORM for REST

– http://grails.org/plugin/gorm-rest-client • Cassandra

– https://github.com/grails/grails-data-mapping/

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http://grails.org/plugin/neo4j

http://grails.org/plugin/redis-gorm

http://grails.org/plugin/gorm-rest-client

https://github.com/grails/grails-data-mapping/tree/master/grails-datastore-gorm-cassandra


Spin up GORM inside a unit test

Unit Testing GORM

Hibernate in Unit Tests• Add a dependency on grails-datastore-test-support

• Provides HibernateTestMixin that will load Hibernate inside a unit test

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test "org.grails:grails-‐datastore-‐test-‐support:1.0-‐grails-‐2.4"

Hibernate in Unit Tests

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import grails.test.mixin.TestMixin import grails.test.mixin.gorm.Domain import grails.test.mixin.hibernate.* import spock.lang.Specification

@Domain(Person) @TestMixin(HibernateTestMixin) class PersonSpec extends Specification { … }

Summary• GORM provides a rich and diverse ecosystem • Goes far beyond relational databases • Can be used standalone or within Grails • Great area to contribute to!

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Stay Connected.

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