Recently Freebase added flags for values: Has No Values and Has Unknown Values. If I query a property's value it will give me null if it is empty or has one of these flags. How do I determine if the value really is empty or if it's flagged?
A good place to find out about something that you see on freebase.com is the source code that drives the site. In particular, for this case:
https://code.google.com/p/freebase-site/source/browse/trunk/www/lib/propbox/js/propbox-edit.js#640
The properties that you need to query are:
/freebase/valuenotation/has_no_value /freebase/valuenotation/has_value
Here's an example:
https://www.freebase.com/m/05r3dj?links&lang=en&filter=%2Ffreebase%2Fvaluenotation%2Fhas_value
A good place to find out about something that you see on freebase.com is the source code that drives the site. In particular, for this case:
https://code.google.com/p/freebase-site/source/browse/trunk/www/lib/propbox/js/propbox-edit.js#640
The properties that you need to query are:
Here's an example:
https://www.freebase.com/m/05r3dj?links&lang=en&filter=%2Ffreebase%2Fvaluenotation%2Fhas_value