Grails 4 is the next iteration of the Grails web framework. Grails is a developer friendly framework built on top of Spring-boot, Groovy, and now Micronaut.

Status

Grails 4 is released!

I've ported a non-trivial app from Grails 3.3.9 to 4.0.0 as well as updated to JDK11. The total effort was only a few hours - welcome news to many who are upgrading.

Initial app startup time is about 15 seconds - 2x faster than the same app in Grails 3.3.9.

Reloading has changed and there are a few options. The default option is from spring-dev-tools - fast restart. This restarts your app faster then a normal restart, but still can be extremely slow for large projects.

Hot reloading options are JRebel - a paid option that works for JDK8/11 - or spring-loaded though it only supports JDK8 and is no longer maintained. Instructions for spring-loaded

IDE Support all works in Grails 4 (same as 3.3.9) - IntelliJ is still my recommended IDE for any Grails, Groovy, or Java developer.

Updates

There are tons of updates to Grails 4 and the frameworks it builds upon. Here's a list of updates and release notes you should review if you're updating your apps.

• Grails 4
  • Upgrade notes
  • New app diff from 3.3.10 -> 4.0.0
• Micronaut 1.1
• Spring Boot 2.1
• Spring 5.1
• Groovy 2.5
• Hibernate 5.3/5.4 support
• Java 11

Install

SDKMan makes installing and managing a JVM and many frameworks a snap:

sdk install java 11.0.2-open
sdk install grails 4.0.3

Plugins

Plugins are an essential part of the Grails developer experience. Luckily many plugins that worked in Grails 3 work out of the box in Grails 4 - or with only slight modifications due.

Working Plugins

• Spring-Security-Core 4.0.0

  • New delegation password strategy:
  • https://www.baeldung.com/spring-security-5-password-storage
  • If you already used bcrypt can do it all at once too:
  • UPDATE my_users SET password = CONCAT('{bcrypt}', password);

• Spring-session-redis (boot starter)

  • Updated dependencies

compile "org.springframework.boot:spring-boot-starter-data-redis"
compile "org.springframework.session:spring-session-data-redis"

• Spring-Websocket

compile "org.grails.plugins:grails-spring-websocket:2.5.0.RC1"

• Grails-Quartz

buildscript {
    dependencies {
        classpath 'org.grails.plugins:quartz:2.0.13' // Needed to compile *Job classes
    }
}

dependencies {
    compile 'org.grails.plugins:quartz:2.0.13'
    compile 'org.quartz-scheduler:quartz:2.2.1' // Is not pulled in by default
}

• Database Migration Plugin 3.1.0.RC1

• Asset-Pipeline 3.1.0

• External Config

  • Works - use RC1+

    compile 'org.grails.plugins:external-config:2.0.0'

• Spring Security UI

  • https://github.com/grails-plugins/grails-spring-security-ui/issues/111

• Schwartz Plugin

  • 2.0.0.RC1

• Grails Cache Plugin

  • 5.0.0.RC1

• Spring Security OAuth2 Provider

  • 4.0.0-RC1

• Sentry

• Grails Mail

  • 3.0.0

Not working

• Audit-Logging Plugin
  • WIP @ https://github.com/robertoschwald/grails-audit-logging-plugin/pull/183

Resolved

• Asset Pipeline Handlebars issue:
  • Needed to update to change //= require handlebars/handlebars.js to //= require handlebars-runtime

2019-01-13 16:59:42.280  WARN --- [nio-8080-exec-1] asset.pipeline.DirectiveProcessor        : Unable to Locate Asset: /handlebars/handlebars.js
Warning: Nashorn engine is planned to be removed from a future JDK release

• Gson Views
  • Resolved.
  • Unable to render json with simple objects (just get null response)
  • Domain classes dont render:

  Model variable [someDomain] of with value [Description] type [com.x.SomeDomain] is not of the correct type [com.x.SomeDomain]. Stacktrace follows:

• Opened Issue https://github.com/grails/grails-views/issues/202

Other notes Notes

• Hot reload for JDK8 only

  • spring-loaded supports only up to JDK8.
  • Fast reload takes about 5-6 seconds (hopefully can improve)

• org.grails:grails-datastore-rest-client no longer maintained

  • Use a different http client such as
    • micronaut-http-client, http-builder-ng, feign, okhttp, etc
  • Or use the old unmaintained GORM 6 version:

compile('org.grails:grails-datastore-rest-client:6.1.9.RELEASE'){
    exclude group:'org.grails', module:'grails-plugin-converters'
}

• Groovy 2.5.x

  • Doesn't include the Date Utils helpers by default - need to add them in.
  • compile 'org.codehaus.groovy:groovy-dateutil'
  • (Should just update to java.time.*)
  • JDK 11 Warnings (expected)
  • https://dev.to/erichelgeson/removing-illegal-reflective-access-warnings-in-grails-4-393o
  • .pop() & collections behavior changed to align with Java - https://issues.apache.org/jira/browse/GROOVY-9388

• Dependencies changes (Gradle 5.1)

  • An issue where dependencies like com.jameskleeh:excel-builder - don't pull in their dependencies (eg: Apache POI)

• Hibernate Deprecated warnings (expected)
  
  

Hibernate's legacy org.hibernate.Criteria API is deprecated; use the JPA javax.persistence.criteria.CriteriaQuery instead
// and
HHH020100: The Ehcache second-level cache provider for Hibernate is deprecated.  See https://hibernate.atlassian.net/browse/HHH-12441 for details.

• Hide them in logback.groovy
  • logger('org.hibernate.orm.deprecation', ERROR, ['STDOUT'], false)

Notes or tips of your own?

Join us over on the grails-community slack channel or comment below!