@feathers-plus/batch-loader/tests/helpers/make-services.js

Reduce requests to backend services by batching calls and caching records.

const postsStore = [
  { id: 1, body: 'John post', userId: 101, starIds: [102, 103, 104] },
  { id: 2, body: 'Marshall post', userId: 102, starIds: [101, 103, 104] },
  { id: 3, body: 'Barbara post', userId: 103 },
  { id: 4, body: 'Aubree post', userId: 104 }
];

const commentsStore = [
  { id: 11, text: 'John post Marshall comment 11', postId: 1, userId: 102 },
  { id: 12, text: 'John post Marshall comment 12', postId: 1, userId: 102 },
  { id: 13, text: 'John post Marshall comment 13', postId: 1, userId: 102 },
  { id: 14, text: 'Marshall post John comment 14', postId: 2, userId: 101 },
  { id: 15, text: 'Marshall post John comment 15', postId: 2, userId: 101 },
  { id: 16, text: 'Barbara post John comment 16', postId: 3, userId: 101 },
  { id: 17, text: 'Aubree post Marshall comment 17', postId: 4, userId: 102 }
];

const usersStore = [
  { id: 101, name: 'John' },
  { id: 102, name: 'Marshall' },
  { id: 103, name: 'Barbara' },
  { id: 104, name: 'Aubree' }
];

module.exports = {
  posts: makeService(postsStore, 'posts'),
  comments: makeService(commentsStore, 'comments'),
  users: makeService(usersStore, 'users')
};

function makeService (store1, name) {

  return {
    get (id) {
      //console.log(`... ${name} get ${id}`);
      const store = clone(store1);

      for (let i = 0, leni = store.length; i < leni; i++) {
        if (store[i].id === id) return asyncReturn(store[i]);
      }

      throw Error(`post id ${id} not found`);
    },

    find (params) {
      //console.log(`... ${name} find`, params ? params.query : '');
      const store = clone(store1);

      if (!params || !params.query) return asyncReturn(store);

      const field = Object.keys(params.query)[0];
      let value = params.query[field];

      return asyncReturn(store.filter(post => {
        return typeof value !== 'object'
          ? post[field] === value
          : value.$in.indexOf(post[field]) !== -1;
      }));
    }
  };
}

function asyncReturn (value) {
  return new Promise(resolve => {
    setTimeout(() => { resolve(value); }, 10);
  });
}

function clone(obj) {
  return JSON.parse(JSON.stringify(obj));
}