I linked a joSelect control to a record like this: new joSelect(languages, set.link("language"));

This works, except when set.language is initially zero.

I think the problem is in joControl.setValueSource:

setValueSource: function(source) {
    this.valueSource = source;
    source.changeEvent.subscribe(this.setValue, this);
    this.setValue(source.getData() || null);

If source.getData returns zero, it is replaced with null.

I replaced this:

    this.setValue(source.getData() || null);

with this:

    var data = source.getData();
    if (!data && data != 0) data = null;
    this.setValue(data);

which does the same, except if getData returns zero. But I suspect this is not the best solution.

Question: how does joDataSource.getData return "invalid result"? Presumably, it shouldn't just replace any falsy value with null, as some valid values are falsy (0, false, etc).

Cheers, Stewart