Agile Database ModellingNew GORM Features in Grails 1.4

Prepared for SF Grails Café Centro March 2011

by Christian Hang

Thanks to Taulia for hosting and food!!

Agenda

New (GORM) Features in Grails 1.4Quick intro to H2Reverse EngineeringDatabase MigrationsOther new Grails 1.4 featuresSummary

New (GORM) Features in Grails 1.4

Replace HQSQL with H2Best-of-bread in-memory DBBuilt-in web console

New (GORM) Features in Grails 1.4

Replace HQSQL with H2Best-of-breed in-memory DBBuilt-in web console

Reverse Engineering Based on Hibernate's reverse engineering Create GORM classes from existing DB

New (GORM) Features in Grails 1.4

Replace HQSQL with H2Best-of-bread in-memory DBBuilt-in web console

Reverse Engineering Based on Hibernate's reverse engineering Create GORM classes from existing DB

Database MigrationsBased on Liquibase"Revision" the DBAllows track/rollback schema changes

Current Status

No hard dependencies on Grails 1.4Everything available as plugins todayBoth main features developed by Burt Beckwith

Current Status

No hard dependencies on Grails 1.4Everything available as plugins todayBoth main features developed by Burt BeckwithH2 plugin or JAR dependency

com.h2database:h2:1.2.147

Current Status

No hard dependencies on Grails 1.4Everything available as plugins todayBoth main features developed by Burt BeckwithH2 plugin or JAR dependency

com.h2database:h2:1.2.147Reverse Engineering

http://grails-plugins.github.com/grails-db-reverse-engineer/grails install-plugin db-reverse-engineerlatest version 0.3

Current Status

No hard dependencies on Grails 1.4Everything available as plugins todayBoth main features developed by Burt BeckwithH2 plugin or JAR dependency

com.h2database:h2:1.2.147Reverse Engineering

http://grails-plugins.github.com/grails-db-reverse-engineer/grails install-plugin db-reverse-engineerlatest version 0.3

Database Migrationshttp://grails-plugins.github.com/grails-database-migration/grails install-plugin database-migrationlatest version 0.2

Take your DB tools with you

H2 in Grails 1.4

Replaces HSQLDBsupport in-memory, file-based, clustered DBcomes with a build-in web console

http://localhost:8080/appname/dbconsoleAvailable as (insecure) plugin today

Use legacy databases in Grails even faster!

Reverse Engineering

Existing DB + Grails command = GORM classes

Reverse Engineering

Existing DB + Grails command = GORM classesUses DB connection from DataSource.groovyConfiguration in grails-app/conf/Config.groovyStarted with grails db-reverse-engineer

Reverse Engineering

Existing DB + Grails command = GORM classesUses DB connection from DataSource.groovyConfiguration in grails-app/conf/Config.groovyStarted with grails db-reverse-engineerDetailed configuration available

covers many-to-many relationsinclude/exclude tables, columns etc.

Creates belongsTo, hasMany and constraints

Simplest configuration:

grails.plugin.reveng.packageName = com.acme.db

Demo Reverse Engineering

The good and the bad

Recognizes length limitations & constraintsCreates relates between entitiesEven handles composite primary keys

The good and the bad

Recognizes length limitations & constraintsCreates relates between entitiesEven handles composite primary keysCareful: Will probably not get it 100% correct!Always review generated classes

The good and the bad

Recognizes length limitations & constraintsCreates relates between entitiesEven handles composite primary keysCareful: Will probably not get it 100% correct!Always review generated classesStill helps to save a lot of work

Your source code is in VCS,but do you version your DB?

Database Migrations

Liquibase: verbose XML schema changesets

Database Migrations

Liquibase: verbose XML schema changesets

<?xml version="1.0" encoding="UTF-8" standalone="no"?> <databaseChangeLog xmlns="http://www.liquibase.org/xml/ns/dbchangelog" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://www.liquibase.org/xml/ns/dbchangelog http://www.liquibase.org/xml/ns/dbchangelog/dbchangelog-2.0.xsd"> <changeSet author="christianhang (generated)" id="1300172497244-1"> <createTable tableName="BLURB"> <column autoIncrement="true" name="ID" type="BIGINT"> <constraints nullable="false" primaryKey="true" primaryKeyName="CONSTRAINT_3"/> </column> <column name="VERSION" type="BIGINT"> <constraints nullable="false"/> </column> <column name="CONTENT" type="VARCHAR(100000)"/> <column name="NAME" type="VARCHAR(255)"> <constraints nullable="false"/> </column> </createTable> </changeSet> ....

Database Migrations

Liquibase: verbose XML schema changesetsPlugin: Groovy changesets & automation

Database Migrations

Liquibase: verbose XML schema changesetsPlugin: Groovy changesets & automation

databaseChangeLog = {

changeSet(author: "christianhang (generated)", id: "1300168672278-1") {createTable(tableName: "BLURB") {column(autoIncrement: "true", name: "ID", type: "BIGINT") {constraints(nullable: "false", primaryKey: "true", primaryKeyName: "CONSTRAINT_3")}

column(name: "VERSION", type: "BIGINT") {constraints(nullable: "false")}

column(name: "CONTENT", type: "VARCHAR(100000)")

column(name: "NAME", type: "VARCHAR(255)") {constraints(nullable: "false")}}} ...

Database Migrations

Liquibase: verbose XML schema changesetsPlugin: Groovy changesets & automation

Automatically generate changelogs grails dbm-generate-changelog changelog.groovy grails dbm-gorm-diff

Apply changelogs to database grails dbm-changelog-sync changelog.groovy grails dbm-update

Rollback changes grails dbm-rollback-count grails dbm-rollback-to-date

Database Migrations

Liquibase: verbose XML schema changesetsPlugin: Groovy changesets & automationTwo options

track changes manually (changeset first)create automatic diffs (GORM first)

Database Migrations

Liquibase: verbose XML schema changesetsPlugin: Groovy changesets & automationTwo options

track changes manually (changeset first)create automatic diffs (GORM first)

Allows to track schema changes in VCSCreate DB from scratchApply/rollback incremental changes

Database Migrations

Liquibase: verbose XML schema changesetsPlugin: Groovy changesets & automationTwo options

track changes manually (changeset first)create automatic diffs (GORM first)

Allows to track schema changes in VCSCreate DB from scratchApply/rollback incremental changes

Possibilities:Simplifies development with changing DBManage updates to production DB

Demo Database Migrations

Issues to watch out for

BACKUP your database!Always review automatic changesets!

Issues to watch out for

BACKUP your database!Always review automatic changesets!Indexes, triggers etc. might be missedChecksum errors

Changes tracked by filename ingrails-app/conf/migrations/xxxx.groovyIt doesn't like changeset changes

Summary

New goodies before Grails 1.4 releaseLots of automation when working with databasesReverse Engineering simplifies app setupBest practice: Version your DB

References

http://grails-plugins.github.com/grails-db-reverse-engineer/docs/manual/index.html

http://grails-plugins.github.com/grails-db-reverse-engineer/docs/manual/index.html

http://fbflex.wordpress.com/2011/01/19/working-with-the-grails-database-migration-plugin/

http://burtbeckwith.com/blog/?p=376

ContactEmail: christian.hang@gmail.comTwitter: @livingtocodeBlog: livingtocode.com

http://sfgrails.com@sfgrails

Thanks to Taulia for hosting and food!!