Beginner Groovy - grails

Question

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

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 If so it's quite outdated.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
}

Answer 2

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.