Re: FormMaps and indexed elements/collections

Bradley Hill wrote:
>   I haven't seen any examples or mention of it in the mail archives, but this 
> has to be a common issue.
>   
>   I'm looking to create forms with indexed property sets, e.g. name1, name2, 
> nameN, value1, value2, valueN.  I don't know until runtime how many of these 
> properties there will be.  
>   
>   Is there a way to handle arrays and collections of values in the Barracuda 
> forms validation package?  Struts will recognize and map parameters with names 
> like "name[n]" and insert them properly into beans with indexed getter/setter 
> methods.  Is there similar functionality in Barracuda or would it be easy for me 
> to add?

If you want to map and validate such values, things are easy: As HTML 
doesn't know anything about indexed/mapped values, you will have to 
create distinct names for every entry in your collection. E.g. for a 
list you do

<input type="text" name="mylist_1" value="foo"/>

Its no problem to create a FormMap with a element for every single of 
these input fields.

The only thing missing is a convinience-function to access such a list 
of values. But thats not too hard - simply extend DefaultFormMap (or 
RepopulationFormMap) with methods like these (beware of pseudo-code):

public Map getElementAsMap(String prefix) {
	Map result = new HashMap();
         for(FormElement element in getElements()) {
            if(element.getName().startsWith(prefix)) {
               result.put(element.getName().substring(prefix.length() + 
1), element.getVal());
            }
         }
         return result;
}

For a list, you want to convert the keys to ints and put the values into 
the result at the specified position.


Now, for rendering such stuff, things get a little bit more complicated. 
For every mapped/indexed value, you have to create a IterativeModel, so 
you can populate its data.

I could imagine the 2 new FormElements for the RepopulationFormMap could 
add your functionality quite easy - look into CheckBoxGroupElement. Then 
you could even access the value directly as Map/List with 
getElement(name) on RepopulationFormMap.


Regards, Diez