GRAILS Liquibase migration - Rename Column

changeSet(author: "name", id: "my-id") {
    renameColumn(tableName: "table-name", oldColumnName: "old-name", newColumnName: "new-name")
}

GRAILS / GROOVY -- Merging / combining sublist into single list

Using flatten we can easily merge sublists into a single list.

def sublists = [['a','b','c'],['d','e','f']]

println sublists.flatten()
// prints [a, b, c, d, e, f]

GRAILS spring security authentication success event

There are many times when we would like to do something when a user has successfully logged in, like putting a log entry, resetting failed counters etc. Below is a snippet of code which does something similar. Place this piece of code in your grails Config.groovy file.

grails.plugins.springsecurity.useSecurityEventListener = true
grails.plugins.springsecurity.onInteractiveAuthenticationSuccessEvent = { e, appCtx ->

    println "User " + appCtx.springSecurityService.principal.id + " has successfully logged in"
    ...
    ...    

}

GRAILS Configuration -- Different / External Config Files

External config or extra configuration files could be added your grails config.groovy file. Just replace the file names and place this piece of code right at the top of your config.groovy file.

def customConfigLocations = []
if (new File("${userHome}/.myConfig/global-config.groovy").exists()) customConfigLocations.add("file:${userHome}/.myConfig/global-config.groovy")

if (new File("${userHome}/.myConfig/${appName}-config.groovy").exists()) customConfigLocations.add("file:${userHome}/.myConfig/${appName}-config.groovy")

if (customConfigLocations.empty) {
    println("No external configuration available......")
}else {
    grails.config.locations = customConfigLocations
    println("loading configuration from: :${grails.config.locations}")
}

GRAILS forcing file download

Put the below code in your controller to force download a file in grails.

class DownloadController {
  def downloadFile() {
    InputStream contentStream
    try {
        def file = new File("")  
        response.setHeader "Content-disposition", "attachment; filename=filename-with-extension"
        response.setHeader("Content-Length", "file-size")
        response.setContentType("file-mime-type")
        contentStream = file.newInputStream()
        response.outputStream << contentStream
        webRequest.renderView = false
    } finally {
        IOUtils.closeQuietly(contentStream)
    }
  }
}

GRAILS shared / common custom validator

We can define our custom validation logic in config.groovy like below.

def dobLowerLimit = Date.parse('MM/dd/yyyy','01/01/1900')
grails.gorm.default.constraints = {
    birthDateValidator(
            validator: { value, obj ->
                if (value) {
                    if (value < dobLowerLimit) {
                        return ['past.date.error']
                    } else if (value > new Date()) {
                        return ['future.date.error']
                    }
                }
            }
    )
}

The we use it in different classes like below

class Employee {

    Date birthDate

    static constraints = {
       birthDate nullable: false, blank: false, shared: "birthDateValidator"
    }
}

class Customer {

    Date birthDate

    static constraints = {
       birthDate nullable: false, blank: false, shared: "birthDateValidator"
    }
}

GRAILS Injecting services or classes into groovy source

Assuming you have below service class in your grails service(grails-app/services) directory.

class MyService {    
   def printSomething() {
     println "Hello World!!!"
   }
}

And we also have a groovy class under the src(src/groovy) directory and we wanted to inject MyService in this class like below.

class HelloWorld {
  MyService myService

  def printHelloWorld() {
     myService.printSomething();
  }
}  

Finally, we put our injection logic in resources.groovy(grails-app/conf/spring/resources.groovy)

import package.HelloWorld

beans = {
helloWorld(HelloWorld) {
        myService = ref("myService")
    }
}