GraphQL Dataloader factory TypeORM Example

BaseEntity.ts

import { BaseEntity as typeOrmEntity, ObjectType } from "typeorm";
import { ObjectUtils } from "typeorm/util/ObjectUtils";
import * as DataLoader from "dataloader";

// Creating our own BaseEntity Class...
export class BaseEntity extends typeOrmEntity {
  id: string;
  constructor() {
    super();
  }

  /* 
    Create a static method that all our entities can use
    This will dyanimcally call the right repository find method
    based on the entity calling the loader. It will work just like 
    any other dataloader after initialization
  */
  static getDataloader<T extends BaseEntity>(
    this: ObjectType<T>,
    options?: DataLoader.Options<string, T>
  ): DataLoader<string, T> {
    const batch = async (entityIds: string[]) => {
      const records = await (this as any).getRepository().findByIds(entityIds);
      const recordMap: { [key: string]: T } = {};
      records.forEach((record: T) => (recordMap[record.id] = record));
      return entityIds.map(id => recordMap[id]);
    };
    return new DataLoader(batch, options);
  }

}
    
    
    
  //Example Usage:
  const resolver = (id) => User.getDataloader().load(id)