Copying html attributes on Lift bindings
Friday, September 18th, 2009Since Java and Scala are complementary, I will post Scala-related stuff here, too (without creating a new blog).
Today’s tip refers to Lift (Scala’s JavaEE/Rails/Grails/Django). Suppose your webdesigner gives you this XHTML:
<input type="text" class="x" style="width: 100px;"/>
When you bind this using Lift, one of possible solutions is surround it with a tag:
<mybind:myfield><input type="text" class="x" style="width: 100px;"/></mybind:myfield>
Please notice I put it without spaces or newlines between “mybind:myfield” and “input” - this will be important later.
I prefer this way because this XHTML can be opened in other applications, like Firefox and Dreamweaver, making life easier for the webdesigner.
Then, if I bind it using old mama’s recipe:
bind("mybind", form, "myfield" -> myfield.toForm)
Lift will remove my “input” tag and replace it - destroying “class” and “style”. To solve this, I merge “toForm” tag with original attributes:
def merge(form : => Box[NodeSeq])(input : NodeSeq) : NodeSeq = {
var in = input.first
var attrs = form.open_!.first.attributes
new Elem(in.prefix, in.label,
in.attributes append attrs,
in.scope, Group(in.child))
}
bind("mybind", form,
FuncBindParam("myfield", merge(myfield.toForm)))
Function “merge” takes the form and returns a function that receives the original XHTML and translates it into XHTML with Lift’s attributes (”id”, “name”, “lift:gc”, etc). I guess I can improve it somehow, but works great. And, since I’m keeping only the first child of source XHTML, you need to keep “bind” and “input” together (as I said before).
I know I can use a map function to ignore whitespaces, but I’ll leave it as an later exercise (for you and for me, too).
