No match when using default_value for nested objects

Hello,

I was playing with this cool lib when i stumbled upon the following issue.

When i set default_value to None (or any other value) in a rule’s context, i don’t get any matches for nested objects. Here is a code example :

#! /usr/bin/env python3 

import rule_engine

dic = {
    "a": 1,
    "b": "test1",
    "c": {
        "c1": 2,
        "c2": "test2"
    }
}

rule_text = 'a == 1'

rule1 = rule_engine.Rule(rule_text, context=rule_engine.Context())
rule2 = rule_engine.Rule(rule_text, context=rule_engine.Context(default_value=None))

a_match1 = rule1.matches(dic)
a_match2 = rule2.matches(dic)

assert a_match1 == a_match2

rule_text = 'c.c1 == 2'

rule1 = rule_engine.Rule(rule_text, context=rule_engine.Context())
rule2 = rule_engine.Rule(rule_text, context=rule_engine.Context(default_value=None))

c_match1 = rule1.matches(dic)
c_match2 = rule2.matches(dic)

assert c_match1 == c_match2

Only c_match assertion fails.

I think what happens here is c.c1 is replaced with None. The docs says that default_value is used for missing attributes only. c.c1 is not missing therefore it shouldn’t be replaced with None (or any set default_value).

Great lib by the way.

Thanks in advance!

[zeroSteiner]

Should be fixed in commit 2754422dcbffa2c83f7fa67ac60cd052519a64f2. I made it the caller’s responsibility to determine whether or not the context’s default value should be used. This seemed like the easiest and most accurate way to avoid a possible scenario where the legitimate value is the same as the default value and the resolution process carried on because it couldn’t tell the difference.

I’m going to close this out since I’m confident I’ve addressed the issue. If you want to give it a test, that’d be great. I’ll plan on publishing the new version to include the patch in a few days.

[zeroSteiner]

This bug fix has just been published in version v2.4.1.