Compare None in Python inside rule

[AmiParadkar]

I have the following rule if the county is Australia and State is None then change the value
{
"rule": "country == 'Australia' and (state is None or state == '')",
"Value": "--None--"
}

I have tried

1. state == None
2. state is None
3. state is NULL
4. state == ''

but keep getting the following error

raise ValueError(f"Invalid rule {rs['rule']} in list of rules: {ex}")
ValueError: Invalid rule county == 'Australia' and (state is None or state == '') in list of rules: ('syntax error', LexToken(SYMBOL,'is',1,33))

[AmiParadkar]

Never mind found the solution. Following works

{
"rule": "country == 'Australia' and not state",
"Value": "--None--"
}

[zeroSteiner]

If state is the Python value None then in rule engine it'd be null. You can explicitly check if it's null with state == null. The rule engine expression not state would evaluate to true if state is either a blank string, or null, 0 or a few other things, just like in Python.

PYTHONPATH=$(pwd)/lib python -m rule_engine.debug_repl --edit-console
edit the 'context' and 'thing' objects as necessary
>>> thing = {'country': 'Australia', 'state': None}
>>>  
exiting the edit console...
rule > country == 'Australia' and state == null
result: 
True
rule >