Determing if a SQL select returns an empty set asynchronously? - sql

Question

Is this possible easily? It seems the handleResult method is only executed if the result isn't the empty set.
A thought I had was to have handleResult and handleCompletion be member functions of an object and have handleResult update a member variable that handleCompletion can check. If the variable is set, not empty, if variable unset, empty and can act accordingly.
seems to be overly complicated and hoping there's a better solution?

Answer 1

to sketch out a solution (the thought i had above) (edit2: per comment I made below)
function sql() {
this.results = false;
var me = this;
this.handleResult = function(aResultSet) {
for (var row = aResultSet.getNextRow(); row; row = aResultSet.getNextRow()) {
me.results = true;
var value = row.getResultByName("name");
}
};
this.handleError = function(aError) {
.... //deal with error
};
this.handleCompletion = function(aReason) {
if (me.results) {
....//results
} else {
....//no results
}
if (aReason != Components.interfaces.mozIStorageStatementCallback.REASON_FINISHED) {
....//handle these
};
};
s = new sql();
statement.executeAsync({
handleResult: s.handleResult,
handleError: s.handleError,
handleCompletion: s.handleCompletion
});
is this considered a good way to solve this problem?
edit1: this doesn't behave in the manner I'd expect (it works, but not 100% sure why). i.e. the this.results variable is undefined (not false), if handleResult never runs. So it appers as if handleResult and handleCompletion are operating on a different set of variables than I'd expect.
any help to understand what I'm doing wrong would be appreciated.