Grails:楽観ロックのサンプル

GORM

class Person {
  String name
  Long lock_version
  static transients = [ 'lock_version' ]
  static constraints = {
    version validator: { v, o -> !o.lock_version ?: o.lock_version == v }
  }
}

GSP

<g:form method="post">
  <input type="hidden" name="id" value="${personInstance?.id}"/>
  <input type="hidden" name="version" value="${personInstance?.version}"/>

PersonControllerの一部

  def update = {
    def personInstance = Person.get(params.id)
    if (personInstance) {
      personInstance.properties = params
      if (!personInstance.hasErrors() && personInstance.save()) {
        flash.message = "Person ${params.id} updated"
        redirect(action: show, id: personInstance.id)
      }
      else {
        render(view: 'edit', model: [personInstance: personInstance])
      }
    }
    else {
      flash.message = "Person not found with id ${params.id}"
      redirect(action: edit, id: params.id)
    }
  }