BullMQ FlowJobBuilder

flow-job.builder.ts

import { FlowJob } from "bullmq";

export class FlowJobBuilder {

  private job: FlowJob

  constructor(
    firstJob: FlowJob,
  ) {
    this.job = { ...firstJob }
  }

  private assertNoChildren(parent: FlowJob): asserts parent is Omit<FlowJob, 'children'> {
    if (Array.isArray(parent.children) && parent.children.length > 0) {
      throw new Error('May not pass job with children to FlowJobBuilder.')
    }
  }

  andThen(parent: Omit<FlowJob, 'children'>): this {
    this.assertNoChildren(parent as FlowJob);
    this.job = {
      ...parent,
      children: [
        { ...this.job }
      ]
    }
    return this;
  }

  build(): FlowJob {
    return this.job;
  }
}