While the Otter framework already exposes a set of generic operators, you might need additional ones that will better fit your use cases.
Let's see how to integrate a whole new operator isTruthy that check if a string or a boolean is equal to true (boolean)
or if it is equal to the "TRUE" or "TRUTHY" string. The operator is not case-sensitive.
First, generate the operator with the command ng g operator [name] --path=[path-to-operators-folder].
The Otter CLI will generate the operator skeleton for you. You are now free to fill it with your own logic:
const isTruthy: Operator<boolean | string> = {
// validate left operand
validateLhs: (value) => typeof value == 'boolean' || typeof value == 'string',
// validate right operand
evaluator: (lhs) => {
if (typeof lhs === 'boolean') {
return lhs;
}
return ["true", "truthy"].indexOf(lhs.toLowerCase()) > -1;
},
name: 'isTruthy'
}Make sure to register your operator in your engine to make it available.
Example :import {RulesEngineRunnerService} from "@o3r/rules-engine";
@Component({
selector: 'app-root',
templateUrl: './app.component.html',
})
export class AppComponent {
constructor(rulesEngine: RulesEngineRunnerService) {
rulesEngine.upsertOperators([isTruthy])
}
}It is now ready to be used in your Rulesets.
[!NOTE] If you administrate your rules in a dedicated UI (CMS or admin UI), you will need to extract your operator metadata. Check out the metadata documentation to see how to do it.
{
"schema": "https://raw.githubusercontent.com/AmadeusITGroup/otter/main/packages/%40o3r/rules-engine/schemas/rulesets.schema.json",
"rulesets": [
{
"id": "6194b61a-1bf3-4c02-8b7c-20f782d68324",
"name": "My Ruleset",
"disabled": false,
"rules": [
{
"id": "5467e501-b9ff-414f-8026-56885d0d7a4b",
"name": "Check if input is Truthy",
"disabled": false,
"outputRuntimeFacts": [],
"inputRuntimeFacts": [],
"rootElement": {
"elementType": "RULE_BLOCK",
"blockType": "IF_ELSE",
"condition": {
"any": [
{
"lhs": {
"type": "FACT",
"value": "userInput"
},
"operator": "isTruthy",
}
]
},
"successElements": [
// Do anything
]
}
}
]
}
]
}