nocobase/packages/plugins/workflow/src/server/instructions/calculation.ts

import parse from 'json-templates';

import evaluators, { Evaluator } from '@nocobase/evaluators';

import { Processor } from '..';
import { JOB_STATUS } from "../constants";
import FlowNodeModel from "../models/FlowNode";
import { Instruction } from ".";



interface CalculationConfig {
  dynamic?: boolean | string;
  engine?: string;
  expression?: string;
}

export default {
  async run(node: FlowNodeModel, prevJob, processor: Processor) {
    const { dynamic = false } = <CalculationConfig>node.config || {};
    let { engine = 'math.js', expression = '' } = node.config;
    let scope = processor.getScope();
    if (dynamic) {
      const parsed = parse(dynamic)(scope) ?? {};
      engine = parsed.engine;
      expression = parsed.expression;
      scope = parse(node.config.scope ?? '')(scope) ?? {};
    }

    const evaluator = <Evaluator | undefined>evaluators.get(engine);

    try {
      const result = evaluator && expression
        ? evaluator(expression, scope)
        : null;
      return {
        result,
        status: JOB_STATUS.RESOLVED
      };
    } catch (e) {
      return {
        result: e.toString(),
        status: JOB_STATUS.ERROR
      }
    }
  }
} as Instruction;