Add ruleset from json

[sergerdn]

Hi, there. Firstly I want to said that I have read https://github.com/hyperjumptech/grule-rule-engine/blob/master/docs/GRL_JSON_en.md many times. But on my side it's not working as expected.

go version go1.17.2 darwin/amd64

package main

import (
	"fmt"
	"github.com/hyperjumptech/grule-rule-engine/pkg"
)

// https://github.com/hyperjumptech/grule-rule-engine/blob/master/docs/GRL_JSON_en.md#expanded-representation
const jsonData = `{
  "name": "SpeedUp",
  "desc": "When testcar is speeding up we increase the speed.",
  "salience": 10,
  "when": {
    "and": [
      {"eq": ["TestCar.SpeedUp", true]},
      {"lt": ["TestCar.Speed", "TestCar.MaxSpeed"]}
    ]
  },
  "then": [
    {"set": ["TestCar.Speed", {"plus": ["TestCar.Speed", "TestCar.SpeedIncrement"]}]},
    {"set": ["DistanceRecord.TotalDistance", {"plus": ["DistanceRecord.TotalDistance", "TestCar.Speed"]}]},
    {"call": ["Log", {"const": "Speed increased"}]}
  ]
}`

func main() {
	// https://github.com/hyperjumptech/grule-rule-engine/blob/master/docs/GRL_JSON_en.md#loading-json-rules
	ruleset, err := pkg.ParseJSONRuleset([]byte(jsonData))
	if err != nil {
		panic(err)
	}
	fmt.Println(ruleset)
}

Result:

panic: json: cannot unmarshal object into Go value of type []pkg.GruleJSON

What I missing?

[niallnsec]

The problem is that pkg.ParseJSONRuleset expects to be given a rule set rather than just a single rule. A rule set is just a JSON array of rules and it is perfectly fine to only have a single rule as long as it is wrapped in an array.

The Load() function of the JSONResource handles both cases transparently, but if you want to manually load a single GRL JSON rule you can call the function pkg.ParseJSONRule() instead.

[sergerdn]

Thank you very much. I solved my problem.