import { ApiField } from '@lcdev/api-fields';

// somewhere, where your model is defined
class EntityA {
  @ApiField()
  publicFieldA: any;

  @ApiField()
  publicFieldB: any;

  privateFieldA: any;
  privateFieldB: any;
}

import { extractApiFieldsMiddleware } from '@lcdev/api-fields-middleware';

// somewhere, where you have a koa router
app
  .get('/foo/bar', extractApiFieldsMiddleware(EntityA), async (ctx, next) => {
    // the body ends up as an object that is, or looks like an 'EntityA'
    ctx.body = new EntityA();

    return next();
  });