executor plugin error: can not call method on null

[rkgrails]

Here is the code that is trying to use the executor plugin's submit and get method. For some reason I am getting following error:

import trials.*
new BootStrap().init()
def bookService = new BookService()
bookService.getAbstractBooks()
 
Exception thrown

java.lang.NullPointerException: Cannot invoke method submit() on null object
        at trials.BookService.getAbstractBooks(BookService.groovy:9)
        at trials.BookService$getAbstractBooks.call(Unknown Source)
        at ConsoleScript0.run(ConsoleScript0:5)

----------------
// I had not imported the Callable as it was not mentioned in the document at github
// but then compiler complained about missing Callable so, I included the java package
// Not sure if this is the reason for the error.
package trials
import java.util.concurrent.Callable

class BookService {
        def executorService

    def getAbstractBooks() {
                log.info "in abstractBooks"
                def future = executorService.submit({
                        getAuthors()
                } as Callable)
               
                return future.get()
    }
       
        def getAuthors() {
                log.info "in getAuthors"
                def authorMap = [:]
                def books = Book.findAll()
                books.each {book ->
                        authorMap[book] = book.author.name
                        println "authorMap[$book]: ${authorMap[book]}"
                }
                log.info "out of getAuthors"
                return authorMap
        }
}

[Ian Roberts]

On 14/11/2012 23:54, rkgrails wrote:
> def bookService = new BookService()

If you "new" your service object directly then it won't get its
dependencies injected.  Instead you need to fetch the bookService bean
from the Spring context - if you're in a grails console it should be
accessible as ctx.bookService.  Also you don't need to do new
BootStrap().init() as that should have happened already as part of the
console startup process.

Ian

--
Ian Roberts               | Department of Computer Science
[hidden email]  | University of Sheffield, UK

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[rkgrails]

Ian,

Thanks for the helpful response! For some reason I do have to use new BootStrap().init() or it won't work. I am using it to load the data in the database. Using ctx works as it removes the exception that I was getting earlier and the method gets called alright. The data gets printed inside the method but then it returns null from the service - any idea what is wrong?

Here is the new output:

groovy> import trials.*
groovy> new BootStrap().init()
groovy> def books = Book.findAll()
groovy> def bookService = ctx.bookService
groovy> print bookService.getAbstractBooks()
 
authorMap[(Falling Star)]: Bill Conner
authorMap[(Blue Moon)]: Bill Conner
authorMap[(Mars Alive)]: Bill Conner
authorMap[(Old Woman)]: Warren Levin
authorMap[(Old Shoe)]: Warren Levin
authorMap[(Very Old Woman)]: Warren Levin
authorMap[(Young Woman)]: Warren Levin
authorMap[(Shades of Grey)]: Cindy Mark
authorMap[(Autumn in Yellow)]: Cindy Mark
authorMap[(Deep Black)]: Cindy Mark
authorMap[(Fat Cat)]: Todd Dander
authorMap[(Big Dog)]: Todd Dander
authorMap[(Pink Gerbil)]: Todd Dander
authorMap[(Running Hamster)]: Todd Dander
authorMap[(Crazy Horse)]: Todd Dander
authorMap[(Dust Storm)]: Lucy Sparks
authorMap[(Marble Storm)]: Lucy Sparks
authorMap[(Diamond Storm)]: Lucy Sparks
authorMap[(Windmill Falling)]: Richard Corsin
authorMap[(Flag on a Breeze)]: Richard Corsin
authorMap[(Nine Leaves)]: Richard Corsin
authorMap[(Moon Nuts)]: Richard Corsin
authorMap[(Cedar Plank)]: Richard Corsin
authorMap[(Horn and Drum)]: Anna Heart
authorMap[(Bayou Billy)]: Anna Heart
authorMap[(Roughing It)]: Anna Heart
authorMap[(Laser Focus)]: Anna Heart
authorMap[(Watching the Moon)]: Leslie Derby
authorMap[(Moonrise Over Shame)]: Leslie Derby
authorMap[(Feral Harness)]: Leslie Derby
authorMap[(Granite Doll)]: Leslie Derby
authorMap[(Vodka Sunrise)]: Leslie Derby
authorMap[(Bull and China)]: Clint Fallow
authorMap[(Tip the Boat)]: Clint Fallow
authorMap[(Calm Raft)]: Clint Fallow
authorMap[(River Surge)]: Clint Fallow
authorMap[(Still in Yellow)]: Lucy Peters
authorMap[(Rags on Fire)]: Lucy Peters
authorMap[(Spin the Moon)]: Lucy Peters
authorMap[(Field of Fey)]: Lucy Peters
authorMap[(Sunflower Vengence)]: Lucy Peters

null


--rakesh

Ian Roberts wrote

On 14/11/2012 23:54, rkgrails wrote:
> def bookService = new BookService()

If you "new" your service object directly then it won't get its
dependencies injected.  Instead you need to fetch the bookService bean
from the Spring context - if you're in a grails console it should be
accessible as ctx.bookService.  Also you don't need to do new
BootStrap().init() as that should have happened already as part of the
console startup process.

Ian

--
Ian Roberts               | Department of Computer Science
[hidden email]  | University of Sheffield, UK

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[Ian Roberts]

On 16/11/2012 01:50, rkgrails wrote:
> groovy> print bookService.getAbstractBooks()
>  
> authorMap[(Falling Star)]: Bill Conner
[snip]
> authorMap[(Sunflower Vengence)]: Lucy Peters
>
> *null*

That is correct, the "null" is the return value of the final "print"
statement.  If you just said

groovy> bookService.getAbstractBooks()

then you would see the list of books as the return value.

Ian

--
Ian Roberts               | Department of Computer Science
[hidden email]  | University of Sheffield, UK

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[rkgrails]

Ian,

The prints that you see on the screen is from within the method that is called by the service. Once service gets the value, it tries to print that and that is what is printing as null.

This is the code for the service:

def getAbstractBooks() {
		log.info "in abstractBooks"
//		def future = callAsync getAuthors
		def future = executorService.submit({
			getAuthors()
		} as Callable)
		def absBooks = future.get()
		
		log.info "out of abstractBooks"
		return absBooks
    }

--rakesh

Ian Roberts wrote

On 16/11/2012 01:50, rkgrails wrote:
> groovy> print bookService.getAbstractBooks()
>  
> authorMap[(Falling Star)]: Bill Conner
[snip]
> authorMap[(Sunflower Vengence)]: Lucy Peters
>
> *null*

That is correct, the "null" is the return value of the final "print"
statement.  If you just said

groovy> bookService.getAbstractBooks()

then you would see the list of books as the return value.

Ian

--
Ian Roberts               | Department of Computer Science
[hidden email]  | University of Sheffield, UK

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