Java Reference
In-Depth Information
Delete Action
The
delete()
action is available, by default, in the edit and show views. Listing 7-25 illustrates the
delete()
action of the
BookController
.
Listing 7-25. The Delete Action of the BookController
def delete(Long id) {
def bookInstance = Book.get(id)
if (!bookInstance) {
flash.message = message(code: 'default.not.found.message', args: [message(code:
'book.label', default: 'Book'), id])
redirect(action: "list")
return
}
try {
bookInstance.delete(flush: true)
flash.message = message(code: 'default.deleted.message', args: [message(code:
'book.label', default: 'Book'), id])
redirect(action: "list")
}
catch (DataIntegrityViolationException e) {
flash.message = message(code: 'default.not.deleted.message',
args: [message(code: 'book.label', default: 'Book'), id])
redirect(action: "show", id: id)
}
}
The
delete()
action attempts to retrieve a
Book
instance and redirects to the list view if it can't find
one. If an instance is found, a try/catch block is entered, where deletion of the instance is tried. If
the deletion is successful, a message is stored in
flash
and redirected to the list view. If there is an
exception, a different message is stored in
flash
and redirected to the show view.
Now that you have seen all the actions generated in the
BookController
for the
Book
class, let's
examine the views generated by static scaffolding for the
Book
class.
Grails Views
Grails uses Groovy Server Pages (GSP) for its view layer. Grails also uses SiteMesh, the page
decoration framework, to help with page layout. SiteMesh merges each of the
.gsp
files into a file
called
main.gsp
to give a consistent look to all the pages. You will begin the generated views with
main.gsp
, which can be found in
\views\layouts
, followed by the four views generated for the
Book
class:
list.gsp
,
show.gsp
,
create.gsp
, and
edit.gsp
. Listing 7-26 illustrates
main.gsp
.
Listing 7-26. main.gsp
1.<!DOCTYPE html>
2.<!--[if lt IE 7 ]><html lang="en" class="no-js ie6"><![endif]-->
3.<!--[if IE 7 ]><html lang="en" class="no-js ie7"><![endif]-->
4.<!--[if IE 8 ]><html lang="en" class="no-js ie8"><![endif]-->
