(Quick Reference) # 3.3.1 Upgrading Plugins Version: 3.2.8 ## 3.3.1 Upgrading Plugins To upgrade a Grails 2.x plugin to Grails 3.x you need to make a number of different changes. This documentation will outline the steps that were taken to upgrade the Quartz plugin to Grails 3, each individual plugin may differ. #### Step 1 - Create a new Grails 3 plugin The first step is to create a new Grails 3 plugin using the command line:
    $ grails create-plugin quartz
This will create a Grails 3 plugin in the `quartz` directory. #### Step 2 - Copy sources from the original Grails 2 plugin The next step is to copy the sources from the original Grails 2 plugin to the Grails 3 plugin:
    # first the sources
    cp -rf ../quartz-2.x/src/groovy/ src/main/groovy
    cp -rf ../quartz-2.x/src/java/ src/main/groovy
    cp -rf ../quartz-2.x/grails-app/ grails-app
    cp -rf ../quartz-2.x/QuartzGrailsPlugin.groovy src/main/groovy/grails/plugins/quartz

    # then the tests
    cp -rf ../quartz-2.x/test/unit/* src/test/groovy
    mkdir -p src/integration-test/groovy
    cp -rf ../quartz-2.x/test/integration/* src/integration-test/groovy

    # then templates / other resources
    cp -rf ../quartz-2.x/src/templates/ src/main/templates
#### Step 3 - Alter the plugin descriptor You will need to add a package declaration to the plugin descriptor. In this case `QuartzGrailsPlugin` is modified as follows:
    // add package declaration
    package grails.plugins.quartz
    ...
    class QuartzGrailsPlugin extends Plugin {
     ...
    }
In addition you should remove the `version` property from the descriptor as this is now defined in `build.gradle`. #### Step 4 - Update the Gradle build with required dependencies The repositories and dependencies defined in `grails-app/conf/BuildConfig.groovy` of the original Grails 2.x plugin will need to be defined in `build.gradle` of the new Grails 3.x plugin:
    compile("org.quartz-scheduler:quartz:2.2.1") {
        exclude group: 'slf4j-api', module: 'c3p0'
      }
It is recommended to use the latest stable, Grails 3+ compatible version of plugins. (Grails 2.x plugin versions will not work.) #### Step 5 - Modify Package Imports In Grails 3.x all internal APIs can be found in the `org.grails` package and public facing APIs in the `grails` package. The `org.codehaus.groovy.grails` package no longer exists. All package declaration in sources should be modified for the new location of the respective classes. Example `org.codehaus.groovy.grails.commons.GrailsApplication` is now `grails.core.GrailsApplication`. #### Step 5 - Migrate Plugin Specific Config to application.yml Some plugins define a default configuration file. For example the Quartz plugin defines a file called `grails-app/conf/DefaultQuartzConfig.groovy`. In Grails 3.x this default configuration can be migrated to `grails-app/conf/application.yml` and it will automatically be loaded by Grails without requiring manual configuration merging. #### Step 6 - Update plugin exclusions Old plugins may have a `pluginExcludes` property defined that lists the patterns for any files that should not be included in the plugin package. This is normally used to exclude artifacts such as domain classes that are used in the plugin’s integration tests. You generally don’t want these polluting the target application. This property is no longer sufficient in Grails 3, and nor can you use source paths. Instead, you must specify patterns that match the paths of the compiled classes. For example, imagine you have some test domain classes in the `grails-app/domain/plugin/tests` directory. You should first change the `pluginExcludes` value to
    def pluginExcludes = ["plugin/test/**"]
and then add this block to the build file:
    jar {
        exclude "plugin/test/**"
    }
The easiest way to ensure these patterns work effectively is to put all your non-packaged class into a distinct Java package so that there is a clean separation between the main plugin classes and the rest. #### Step 7 - Register ArtefactHandler Definitions In Grails 3.x ArtefactHandler definitions written in Java need to be declared in a file called `src/main/resources/META-INF/grails.factories` since these need to be known at compile time.
| If the `ArtefactHandler` is written in Groovy this step can be skipped as Grails will automatically create the `grails.factories` file during compilation.
The Quartz plugin requires the following definition to register the `ArtrefactHandler`:
    grails.core.ArtefactHandler=grails.plugins.quartz.JobArtefactHandler
#### Step 8 - Migrate Code Generation Scripts Many plugins previously defined command line scripts in Gant. In Grails 3.x command line scripts have been replaced by two new features: Code generation scripts and Gradle tasks. If your script is doing simple code generation then for many cases a code generation script can replace an old Gant script. The `create-job` script provided by the Quartz plugin in Grails 2.x was defined in `scripts/CreateJob.groovy` as:
    includeTargets << grailsScript("_GrailsCreateArtifacts")

    target(createJob: "Creates a new Quartz scheduled job") {
        depends(checkVersion, parseArguments)

        def type = "Job"
        promptForName(type: type)

        for (name in argsMap.params) {
            name = purgeRedundantArtifactSuffix(name, type)
            createArtifact(name: name, suffix: type, type: type, path: "grails-app/jobs")
            createUnitTest(name: name, suffix: type)
        }
    }

    setDefaultTarget 'createJob'
A replacement Grails 3.x compatible script can be created using the `create-script` command:
    $ grails create-script create-job
Which creates a new script called `src/main/scripts/create-job.groovy`. Using the new code generation API it is simple to implement:
    description("Creates a new Quartz scheduled job") {
        usage "grails create-job <<JOB NAME>>"
        argument name:'Job Name', description:"The name of the job"
    }

    model = model( args[0] )
    render  template:"Job.groovy",
            destination: file( "grails-app/jobs/$model.packagePath/${model.simpleName}Job.groovy"),
            model: model
Please refer to the documentation on Creating Custom Scripts for more information. #### Migrating More Complex Scripts Using Gradle Tasks Using the old Grails 2.x build system it was relatively common to spin up Grails inside the command line. In Grails 3.x it is not possible to load a Grails application within a code generation script created by the create-script command. Instead a new mechanism specific to plugins exists via the create-command command. The `create-command` command will create a new ApplicationCommand, for example the following command will execute a query:
    import grails.dev.commands.*
    import javax.sql.*
    import groovy.sql.*
    import org.springframework.beans.factory.annotation.*

    class RunQueryCommand implements ApplicationCommand {

      @Autowired
      DataSource dataSource

      boolean handle(ExecutionContext ctx) {
          def sql = new Sql(dataSource)
          println sql.executeQuery("select * from foo")
          return true
      }
    }
With this command in place once the plugin is installed into your local Maven cache you can add the plugin to both the build classpath and the runtime classpath of the application’s `build.gradle` file:
    buildscript {
      ...
      dependencies {
        classpath "org.grails.plugins:myplugin:0.1-SNAPSHOT"
      }
    }
    ...
    dependencies {
      runtime "org.grails.plugins:myplugin:0.1-SNAPSHOT"
    }
Grails will automatically create a Gradle task called `runQuery` and a command named `run-query` so both the following examples will execute the command:
    $ grails run-query
    $ gradle runQuery
#### Step 8 - Delete Files that were migrated or no longer used You should now delete and cleanup the project of any files no longer required by Grails 3.x (`BuildConfig.groovy`, `Config.groovy`, `DataSource.groovy` etc.) | Quick Reference (hide)