Google App Maker table query _notContains doesn't work

Question

App Maker > Page > Table > Events > onAttach

works:

var datasource = widget.datasource;
datasource.query.filters.readByUsers._contains = 'Susanne';
datasource.load();

doesn't work:

var datasource = widget.datasource;
datasource.query.filters.readByUsers._notContains = 'Susanne';
datasource.load();

Any filter with _equals works too.

Can anyone say why? Or maybe the even better question is: How do you set filtered table views in app maker?

Again: How do you exactly set filters for your tables?

Answer 1

the correct answer was:

because the field was "null"

so you need to add the filter "_notEquals = null;" to get results