Cant get field names from grid

Hi all, I am upgrading my ExtJS and I have an issue.

I am trying to get the values of all of my fields in a selected row, in ExtJS 3, the following worked

Code:

var record = grid.getStore().getAt(rowIndex);
        var urlParams = ''; 
                var title = ' ';  
                document.body.style.cursor = 'wait'; 
        Ext.each(record.fields.keys, function(fldNam, index, allItems){
                urlParams = urlParams + '&' + fldNam + '=' + encodeURIComponent(record.get(fldNam));
                };
        });

Now,record.fields.keys does not work, it brings back null values so I never get into the loop.

Any help would be appreciated.

Scott

Cant get field names from grid