8.2.2.3 Search and Filtering - Reference Documentation
Authors: Graeme Rocher, Peter Ledbrook, Marc Palmer, Jeff Brown, Luke Daley, Burt Beckwith, Lari Hotari
Version: 3.1.8
8.2.2.3 Search and Filtering
If you have collections of objects you often need to sort and filter them. Use the findAll and grep tags for these tasks:Stephen King's Books: <g:findAll in="${books}" expr="it.author == 'Stephen King'"> <p>Title: ${it.title}</p> </g:findAll>
expr
attribute contains a Groovy expression that can be used as a filter. The grep tag does a similar job, for example filtering by class:<g:grep in="${books}" filter="NonFictionBooks.class"> <p>Title: ${it.title}</p> </g:grep>
<g:grep in="${books.title}" filter="~/.*?Groovy.*?/"> <p>Title: ${it}</p> </g:grep>
books
variable is a collection of Book
instances. Since each Book
has a title
, you can obtain a list of Book titles using the expression books.title
. Groovy will auto-magically iterate the collection, obtain each title, and return a new list!