Grails pitfalls: Controllers and how to reuse code

There're a lot of common repetitive tasks that arises when coding controllers, services...etc. I've seen many times repeating code that has to do with pagination.

def list() {
    params.max = params.max ?: grailsApplication.config.list.default.maxElements
  
    def result = GeographicArea.findAll(params)        
    render view: 'list', model: [list:result]
}

It's really painful to repeat the code to establish default maximum or minimum number of results every time we have to deal with some pagination. It's easier to create a method maybe in some parent class, to be able to call it from those classes inheriting that class. We can use inheritance, mixins, AST...etc.

The pros of using inheritance is you have the behavior because of compilation (AST would be the same here) while doing Mixins would have a performance penalty.

Many times my favorite choice is to inherit a BaseController where I include most of the boilerplate code.

class BaseController{
  
 def configurationService

    def getPaginationParams(){
      if (!params.max){
        params.max = configurationService.defaulMaximumListElements()

        //params.min...etc
      }
      params
    }
  
  }

And then I make the child class to extend the BaseController class

class GeographicAreaController extends BaseController{  
    def list() {    
       def result = GeographicArea.findAll(paginationParams)        
       render view: 'list', model: [list:result]
      }   
}