Native Filter can't work when face NULL value or empty string

[zhaoyongjie]

Native Filter can't work when facing NULL value or an empty string, and this behavior is not consistent with explore page.

native.filter.mov

How to reproduce the bug

1. make a temporary table with a single text column by database client or SQLLab

create table testing_empty_string(
  name varchar(255)
);
insert into testing_empty_string
values
  (null),
  (''),
  ('foo');

2. create a dataset from above table
3. create a chart and dashboard from above dataset
4. create a Native Filter from the dashboard
5. got error when select <NULL> on dashboard
6. got an empty placeholder when select <empty string> on dashboard
7. got an error when select <NULL> on explore

Expected results

1. Native filter should work with NULL
2. Native filter should show when got a empty string
3. filter should work with NULL on explore page

Actual results

Native filter can't work when facing NULL or Empty string

Environment

• browser type and version: latest Firefox
• superset version: current master branch(d645579)

Checklist

Make sure to follow these steps before submitting your issue - thank you!

• I have checked the superset logs for python stacktraces and included it here as text if there are any.
• I have reproduced the issue with at least the latest released version of superset.
• I have checked the issue tracker for the same issue and I haven't found one similar.

[villebro]

Repro'd, thanks for reporting!

[michael-s-molina]

Fixed by #19326

[zhaoyongjie]

Hi @michael-s-molina, The issue is still, so I reopen it. The explore page can't filter the null value.