How to autowire a service in grails (2.5.5) with multiple capital letters at front

问题

I have a domain class named ABCDCode and created a service for the this ABCDCodeService. Now I want to use this service in controllers so I wrote it like below:

class TestController{
      ABCDCode abcdCode

      def index(int id){
           abcdCode.getData(id) //Here I am getting NullPOinterException
      }
}

I am suspecting something wrong with the autowiring by name.

回答1:

Grails looks first two characters for beans naming. If the second character of the controller/service is capital then Grails did not convert the first character to lower case.

e.g., TestService bean name is testService and TEstService bean name is TEstService.

So, your code becomes

ABCDCode ABCDCode

def index(int id){
    ABCDCode.getData(id)
}

But if you want to user abcdCode as bean name, then you can do this with the help of resources.groovy. Add the following to your resources.groovy file--

beans = {
    springConfig.addAlias 'abcdCode', 'ABCDCode'
}

回答2:

class TestController{
  ABCDCode aBCDCode
}

should work

回答3:

You have multiple issues.

1) You assign a member variable but it is never initialized, therefore you get a NullPointerException. You need to get the instance from your database by id first.

2) Be aware that the controller needs to be thread-safe, by assigning the member variable in the controller scope it will be used for many calls at the same time with unpredictible outcome.

3) Names like ABCDCode are against grails naming conventions. Use AbcdCode for the domain and AbcdCodeService for the service and all is well.

This would be the correct approach with the domain class AbcdCode and the corresponding service AbcdCodeService:

// if not in the same module
import AbcdCode

class TestController {

    // correct injection of the service
    def abcdCodeService 

    // ids are Long, but you could omit the type
    def index(Long id) {
       // get instance from database by id, moved to method scope
       def abcdCode = AbcdCode.get(id) 
       // note the "?." to prevent NullpointerException in case
       // an abcdCode with id was not found.
       def data = abcdCode?.getData() 
  }

}

来源：https://stackoverflow.com/questions/50810310/how-to-autowire-a-service-in-grails-2-5-5-with-multiple-capital-letters-at-fro

标签

grails

autowired