Groovy use
#{extends} tag to specify the layout template you want to apply to the current template. On the layout template side, you can use #{doLayout} tag to load the content from sub template. Here is the typical scenario you met on Groovy template:
1. views/Application/index.html:
#{extends "main.html"/}
Home
...
2. views/main.html:
<!DOCTYPE html> <html> <head> ... </head> <body> ...#{doLayout/}... </body> </html>
Rythm use pretty much the same thing (
@extends and @doLayout tag). Here is what they look like in Rythm:
1. rythm/Application/index.html:
@extends(main)Home
...
2. rythm/main.html:
<!DOCTYPE html> <html> <head> ... </head> <body> ...@doLayout()... </body> </html>
Pretty simple, isn't it? One place worth attention. I use
@extends(main) instead of @extends("main.html"). Actually I could use the latter notation, but it is redundant:
- template inheritance is static, which happen at parsing time, so the quotation mark is redundant
- template file extension is deduct using the current template format, thus ".html" is redundant
app/views/themes/blueSky/main.html, to reference it in extends tag you do it this way in groovy:
#{extends "themes/blueSky/main.html"/}
In Rythm you can copy the groovy notation:
@extends("themes/blueSky/main.html")
But I recommend you to use the simple Java package notation:
@extends(themes.blueSky.main)Note, you are free to use relative path and import path shortcuts when you reference the layout template in extends tag, click here to understand relative and import path shortcut.
In addition,
@render() is an alias of @doLayout(). They are two identical tags, and it's up to you to decide which one fit your taste.
Now let's see something interesting.
Passing parameter to layout template
So you can pass parameter from content template to layout template via the
#set and #get. Let's say you have a layout template main.html:
...And in your content template, say index.html:#{doLayout/}
#{extends "main.html"/}
...
#{set theme:"blueSky"/}
...
You can basically follow the same pattern in Rythm. Here is the main.html:
...And the content template:@doLayout()
@extends(main) ... @set(theme:"blueSky") ...Every thing looks good. However you have more than one way to achieve it in Rythm. Now let's define main.html like the follows:
@args String theme ...And the content template changed accordingly:@doLayout()
@extends(main, "blueSky") ...It's more clean and simple than the clumsy
@set and @get, isn't it?
Render sections
So what if you want the content template provides section contents to be inject into different places in the layout template? Groovy templates comes to get/set again. Let's see the main.html in Groovy:
...And the content template:#{doLayout/}...
#{extends "main.html/}
...
#{set "sidebar"}
- menu-1 ...
...And the content template in rythm version:@render()@// as we said before @render() is an alias of @doLayout() ...
@extends(main)
...
@section("sidebar") {
- menu-1 ...
...Now you can omit the footer section from your content template, Rythm will pick up default content automatically!@render()@// as we said before @render() is an alias of @doLayout() ...
In this article we introduced the differences and similarity between Groovy and Rythm on template layout management. We see how Rythm use
@extends and @doLayout or @render tag to support layout reuse in template authoring. In the next post I am going to introduce you to another powerful feature of Rythm template engine: tags. See you soon!
See also: Step by step migrate your Groovy template to Rythm template - Part One
