Beginner Groovy Question:

Question

Hi there, I'm following the code examples in 'The Definitive Guide to Grails' by Graeme Keith Rocher, and have come across a rather unusual stumbling block.

Essentially, 2 domain classes exist - Bookmark & Tag.

Bookmark:

class Bookmark {
static hasMany = [tags:Tag]

URL url
String title
String notes
Date dateCreated = new Date()

}

Tag:

class Tag{
static belongsTo= Bookmark

Bookmark bookmark
String name

}

I'm instructed to launch the Grails Console (is this the same as the groovy console)and create a new object as follows.

def b = new Bookmark(url: new URL('http://grails.org/'), title:'Grails', notes:'Groovy')

This results in:

Result: Bookmark : null

According to the book, GORM automatically provides an implementation of an addTag method. So I code...

b.addTag( new Tag(name: 'grails'))

Only to get whammed with the error message:

Exception thrown: No such property: b for class: ConsoleScript1

groovy.lang.MissingPropertyException: No such property: b for class: ConsoleScript1 at ConsoleScript1.run(ConsoleScript1:2)

The author hasn't accounted for this in the book. I was wondering if anyone could help me out?

Thanks.

Answer 1

The groovy console is not the same as the grails console. To access the grails console, type grails console in your application directory - you should get a Java GUI app. It's possible that the example will work then because grails add some stuff to the standard Groovy.

Also, your problem isn't the addTag method, but the item b that you defined which cannot be found. Try entering the whole script into the console at once and executing it, instead of executing it line by line.

Answer 2

Are you reading the 1st edition of the book? If so it's quite outdated. The add* methods have been deprecated since 0.5. It was replaced by addTo* so do this instead:

b.addToTags( new Tag(name: 'grails'))

Assuming your code example shouldn't have Bookmarks defined twice (copy and paste error?) and Tag might look like this:

class Tag {
    String name
}