DDevelopment & Design

How to change theme in Ext-Gwt (GXT) application

  • byRafal P
  • August 13, 2010
  • 2 minute read

Some time ago Sencha company included new theme in their GXT library. It’s called SLATE and can be viewed in GXT Explorer demo on this site: http://www.sencha.com/examples/explorer.html. I’ve been searching, but I coudn’t find any clear information in web, how to made my gwt app to change theme to new skin instead of standard BLUE or GREY themes. After short investigating I realized, that everything is easy, but only if You keep standard paths in Your app to css/images.

First of all You have to copy to Your’s project directory some directories from GXT example zip file (can be downloaded here: http://www.sencha.com/products/gwt/download.php). Those directories are: css (with BLUE/GREY theme’s csses), images (all gxt standard images) and themes (new SLATE theme). They can be found in resource directory in gxt-x.x.x zip file.

Now, after copying directories to own app in gwt html entry point file it has to be placed following line:   < link rel=”stylesheet” type=”text/css” href=”css/gxt-all.css” /&rt;   That’s all. Nothing more gxt’s csses have to be included (instead of what I’ve found on internet). Why ? Becouse we will switch theme in java code later. In apps entry point java file in onModuleLoad() method we need to insert some code. We want to tell GXT, that we will be using SLATE theme as default, but we would like to change it later. This is made by passing ‘false’ parameter in .setDefaultTheme(..) method. Code for this:   ThemeManager.register(Slate.SLATE); //register non standard theme // Theme.GRAY.set(“file”,”css/gxt-gray.css”); //set custom css’es path for grey theme // Theme.BLUE.set(“file”,”css/gxt-all.css”); //set custom css’es path for standard blue theme // Slate.SLATE.set(“file”,”gxt/themes/slate/css/xtheme-slate.css”); //set custom path for SLATE theme GXT.setDefaultTheme(Slate.SLATE, false); //set default theme to new SLATE skin

That’s not all. If we would like to rearange our paths (i.e. by moving themes/images/css directories in other places) we have to uncoment commented code and set proper paths.

Because we would like to allow user to switch theme by own. We have to add somewhere in our app’s panels ThemeSelector which will do all work. It’s very easy. Just add somewhere this code:

  [ourContainer].add(new ThemeSelector());

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Grails render as JSON catch

One of a reasons your controller doesn't render a proper response in JSON format might be wrong package name that you use. It is easy to overlook. Import are on top of a file, you look at your code and everything seems to be fine. Except response is still not in JSON format.

Consider this simple controller:

class RestJsonCatchController {
def grailsJson() {
render([first: 'foo', second: 5] as grails.converters.JSON)
    }

def netSfJson() {
render([first: 'foo', second: 5] as net.sf.json.JSON)
    }
}

And now, with finger crossed... We have a winner!

$ curl localhost:8080/example/restJsonCatch/grailsJson
{"first":"foo","second":5}
$ curl localhost:8080/example/restJsonCatch/netSfJson
{first=foo, second=5}

As you can see only grails.converters.JSON converts your response to JSON format. There is no such converter for net.sf.json.JSON, so Grails has no converter to apply and it renders Map normally.

Conclusion: always carefully look at your imports if you're working with JSON in Grails!

Edit: Burt suggested that this is a bug. I've submitted JIRA issue here: GRAILS-9622 render as class that is not a codec should throw exception