/**
*    Chained Selects for jQuery 
*    Copyright (C) 2008 Ziadin Givan www.CodeAssembly.com  
*    
*   settings = { usePost : true, before:function() {}, after: function() {}, default: null, parameters : { parameter1 : 'value1', parameter2 : 'value2'} }	
*   if usePost is true, then the form will use POST to pass the parameters to the target, otherwise will use GET
*   "before" function is called before the ajax request and "after" function is called after the ajax request.
*
*/
jQuery.fn.chainSelect = function( target, url, settings ) {
	return this.each( function() {
		$(this).change( function() {
			settings = jQuery.extend ({
				after : null,
				before : null,
				usePost : true,
				defaultValue : null,
				parameters : {'_id' : $(this).attr('id'), '_name' : $(this).attr('name')}
			}, settings);
	
			settings.parameters._value =  $(this).val();
	
			if (settings.before != null) {
				settings.before( target );
			}
			
			ajaxCallback = function(data, textStatus) {
				$(target).html("");//clear old options
				data = eval(data);//get json array
				for (i = 0; i < data.length; i++) {
					for ( key in data[i] ) {	
						$(target).get(0).add(new Option(data[i][key],[key]), document.all ? i : null);
					}
				}
	
				if (settings.defaultValue != null) {
					$(target).val(settings.defaultValue);//select default value
				}
				else {
					$("option:first", target).attr( "selected", "selected" );//select first option
				}
	
				if (settings.after != null) {
					settings.after(target);
				}
	
				$(target).change();//call next chain
			};
	
			if (settings.usePost == true) {
				$.post( url, settings.parameters, ajaxCallback );
			} else {
				$.get( url, settings.parameters, ajaxCallback );
			}
		});
	});
};