Judge is simple rule engine application in favor for me to learn elixir
If available in Hex, the package can be installed as:
-
Add judge to your list of dependencies in
mix.exs:def deps do [{:judge, "~> 0.0.1"}] end
-
Ensure judge is started before your application:
def application do [applications: [:judge]] end
The Idea of Judge is group rules into a bucket, and then after that you can choose which bucket to use for evaluation.
To create a bucket do:
Judge.Buckets.create(:random_buckets)Then to put a rule at first you need to fetch the bucket:
bucket = Judge.Buckets.lookup(:random_buckets) # if not present it will return :errorafter that you can add a rule in that bucket:
rule = [
decisions: %{name: "judge", age: 22}, # mandatory
conditions: [
%{type: "simple", operator: "is_equal_to", value: "20", param: "amount" }
] #mandatory
bucket = Judge.Buckets.lookup(:random_buckets)
Judge.Knowledge.add(bucket, rule)
as you can see, the mandatory parameters are decisions and conditions. you can put any random value in decisions. Meanwhile for conditions it has to be a list of condition.
For now judge only support a really simple conditions with mandatory attributes: type, operator, value, param.
| Attribute | Data Type | Mandatory | Detail |
|---|---|---|---|
| type | string | yes | type of conditions(for now only support simple) |
| operator | string | yes | definitions on how to compare |
| value | any | yes | expected value |
| param | string | yes | base parameter which its value will be compared with value attribute |
list of allowed operator:
is_equal_to, is_not_equal_to, less_than, bigger_than, bigger_than_or_equal_to, less_than_or_equal_to
to evaluate find bucket that you'll be used then just evaluate it:
bucket = Judge.Buckets.lookup(:random_buckets)
Judge.Knowledge.evaluate(bucket, %{ amount: 22 }) # %{}
Judge.Knowledge.evaluate(bucket, %{ amount: 20 }) # %{name: judge, age: 20}