Switching Grails views

November 22, 2008

This is a repost from my post over at GroovyMag.

I’m planning to do this on a couple other projects, and thought I’d share this with you. It’s not specifically something related to GroovyMag magazine, but is a technique I’m using in a Grails project to make it easy to switch layouts based on the user.

All the default generated views use the meta tag ‘layout’ to point to a GSP file which will get merged with your view file (using sitemesh) to generate the final rendered HTML. Unfortunately these are always hardcoded to ‘main’ rather than a configurable option. So, I’ve taken to modifying the templates used during generation to point to a configuration value.

Run “grails install-templates” then look in src/templates/scaffolding. You’ll see the create/edit/list/show GSP files which are used as the basis for generation.

Edit the files such that the meta line

<meta name=”layout” content=”main” />

looks like this

<meta name=”layout” content=”\${session?.layout?:grailsApplication.config.sitemesh.layout}” />

(Note the Elvis operator above)

Then edit your grails-app/conf/Config.groovy file to have a line that reads

sitemesh.layout = “main”

If you then generate views for an app, everything will continue to work as it normally does by default; specifically, all the views will use the grails-app/views/layouts/main.gsp as a sitemesh wrapper for rendering.

However, you’re now able to set the layout to something different for each user by setting the session.layout value.

If a user has authenticated and is an administrator, perhaps you’d want to have