Question

Im having some troubles getting this ajax call to work. The ajax function pass a simple variable to my python controller and the controller returns the result of a query. Im working with Web2py framework. The error im getting: cannot concatenate ‘str’ and ‘NoneType’ objects. And this is the code:

Ajax Call:

<script>
function TestVolumen() {
    var selectVal = $('#zonas :selected').val();    
    $.ajax({
    data: selectVal ,
    url: '/shell/default/ajax2',
    type: 'POST',
    cache: false,
    dataType: 'string',
    success: function(request) {
    //console.log(request[0]);
    //console.log(request[0].zona);
    selectVal = $('#zonas :selected').val();

        for (x=0;x<request.length;x++){
            if (request[x].zona == selectVal ) {
            //alert(request[x].promedio);
            //alert(request[x].zona);
            $('div#tabs .vol').html(request[x].promedio.toFixed(4));

            }
        }

        }
    });
}
</script>

And this is the python controller:

def ajax2():
import gluon.contrib.simplejson
zona = request.vars

queryvol = "select sells.product1 FROM site inner join zona on site.zone_number = zona.id inner join sells on sells.site = site.id WHERE zona.id =" + zona +" ;', as_dict = True"
vol=db.executesql(queryvol)

return gluon.contrib.simplejson.dumps(vol)

Thanks for the help!! I really appreciate it.

Answer 1

The Python error you see means that the value of zona is simply None. I guess this is due to a fact that you make the AJAX request incorrectly. When making a request you should define the data in { 'variable_name' : value } format. For server-side: note that request.vars is gluon.storage.Storage dictionary-like object.

So, to fix this – modify your AJAX request by removing dataType: 'string', and setting data to something like { 'zona' : selectedVal }. Second – use request.vars['zona'] to get the value on the server-side. Third – before writing Python code any further, read an memorize PEP8 by heart!