RuleSet definition

A RuleSet object is basically a list of predefined rules that will be executed over a given data. A RuleSet can be compared with some kind of policy.

RuleSet object needs to have a name that is passed by the constructor and at least 1 Rule object configured to be applied successfully.

In difference with the Rule object RuleSet doesn’t have an execute method, instead of this RuleSet has the method apply that receive the data. This method do not return any value on success and raise a RuleError if some rule fails his validation.

Basic Usage

To define a RuleSet and add a Rule to the list you can simple add the following code:

from pyruler import RuleSet, Rule

rule_set = RuleSet(name='policy1')
rule_set.add_rule(Rule(name='is-gt-10', resolver=lambda x: x > 10))

rule_set.apply(1)
# => raise RuleError

Add Multiple Rules

You can add all the rules you need to a RuleSet. Rules stored by a RuleSet will be executed in the same exact same order that the rules where added:

from pyruler import RuleSet, Rule

rule_set = RuleSet(name='policy1')
rule_set.add_rule(Rule(name='is-gt-10', resolver=lambda x: x > 10))
rule_set.add_rule(Rule(name='is-lt-20', resolver=lambda x: x > 20))

rule_set.apply(15)
# => None (This is a success validation)

Other way to add multiple rules is by using the method add_many:

from pyruler import RuleSet, Rule

rule_set = RuleSet(name='policy1')

rule_set.add_many([
    Rule(name='is-gt-10', resolver=lambda x: x > 10),
    Rule(name='is-lt-20', resolver=lambda x: x < 20),
])

rule_set.apply(15)
# => None (This is a success validation)

Fail fast execution

You can specify when a RuleSet should trigger an error of a Rule validation. This can be configured by the fail_fast param of the apply method.

By default fail_fast is set to True, this raises a RuleError exception with the first negative assertion returned by a rule of the RuleSet. If fail_fast is set to False all rules will be executed to collect all errors of each configured rule before raise a RuleError exception.

from pyruler import RuleSet, Rule

rule_set = RuleSet(name='policy1')

rule_set.add_many([
    Rule(name='has-foo', resolver=lambda x: 'foo' in x.keys()),
    Rule(name='has-bar', resolver=lambda x: 'bar' in x.keys()),
])

rule_set.apply({'baz': True})
# => raise RuleError exception after execute 'has-foo' rule

rule_set.apply({'baz': True}, fail_fast=False)
# => raise RuleError exception after execute 'has-foo' and 'has-bar' rules