function refreshSubcategories(categories,subcategories,url){
	// get JSON data
	id=$('#'+categories+' option:selected').attr('value');
	if(!url)url='graduate/get/subcategories.html';
    alert(url);
	$.get(url+'?id='+id,null,function(data,textStatus){
		var options='<option value="0">Select job type</option>';
		for(i=0;i<data.results.length;i++){
			options+='<option value="'+data.results[i]['id']+'">'+data.results[i]['name']+'</option>';
		}
		// setting select options
		$('#'+subcategories).html(options);
	},'json');
}
function refreshDropdown(dropdown_id,url,args){
    json=eval("("+args+")");
    // check values of other dropdowns and constructs query
    for(var j in json){
        var v=$('#'+json[j]+' option:selected').attr('value');
        if(url.indexOf('?')){
            url+='&'+j+'='+v;
        }else{
            url+='?'+j+'='+v;
        }
    }
	$.get(url,null,function(data,textStatus){
        var options='';
        if(data.hide){
            $('#'+data.hide).hide()
        }
        if(data.results)for(i in data.results){
			options+='<option value="'+i+'">'+data.results[i]+'</option>';
		}
        if(data.show){
            $('#'+data.show).show()
        }
		// setting select options
		$('#'+dropdown_id).html(options);
	},'json');

}