Can Grails handle POST variables as an array? - php

Question

If you post the following HTML into a PHP script:
<input type="hidden" name="var[0]" value="A" />
<input type="hidden" name="var[2]" value="C" />
<input type="hidden" name="var[1]" value="B" />
You would end up with a variable called $_POST['var'] (that is essentially a HashMap) whose keys/values look like this:
[0] => "A"
[1] => "B"
[2] => "C"
In PHP, I'm then able to do basic array logic on this, for instance I can see that count($_POST['var']) == 3, and I can iterate over it with a foreach statement.
Is there any way to accomplish this, or something similar, in Grails? I noticed that if I pass in the same sort of HTML to Grails, the result is much less intuitive than it is in PHP. What I want to do is to simply be able to access params.var[0], params.var[1], and so on, and likewise be able to examine things like params.var.length.
But this is not the case. What happens is that params.var is undefined, but instead I then have to access request.getParameter('var[0]'), which is obviously pretty useless.
I realize that I could change my HTML to something like this:
<input type="hidden" name="var" value="A" />
<input type="hidden" name="var" value="B" />
<input type="hidden" name="var" value="C" />
But this is far from ideal, because then I have to guarantee that the HTML inputs are in precisely the right order every time. In PHP, it doesn't really matter what order they appear in since I can specify that directly in the name attribute, and the language is smart enough to take care of it.
Am I missing something? Is there any way to accomplish this in Grails?

Answer 1

Actually it does by default, when binding data. See http://grails.org/doc/latest/guide/theWebLayer.html#dataBinding Binding To Collections And Maps.
The data binder can populate and update Collections and Maps. The following code shows a simple example of populating a List of objects in a domain class:
class Band {
String name
static hasMany = [albums: Album]
List albums
}
class Album { String title Integer numberOfTracks }
def bindingMap = [name: 'Genesis',
'albums[0]': [title: 'Foxtrot', numberOfTracks: 6],
'albums[1]': [title: 'Nursery Cryme', numberOfTracks: 7]]
def band = new Band(bindingMap)
assert band.name == 'Genesis'
assert band.albums.size() == 2
assert band.albums[0].title == 'Foxtrot'
assert band.albums[0].numberOfTracks == 6
// ...
Also if you want to deal with this on your own, you can of course write it yourself. E.g.:
params.collect{it=~/${name}\[(\d+)\]/}.findAll().collectEntries{[it.group(1).toInteger(), params[it.group(0)]]}