Graphql Dataloader文件结构和上下文

src/
├── dataloaders/
│   ├── index.js
│   ├── userLoader.js
│   ├── postLoader.js
│   └── ...
├── models/
│   ├── User.js
│   ├── Post.js
│   └── ...
├── resolvers/
│   ├── index.js
│   ├── userResolver.js
│   ├── postResolver.js
│   └── ...
└── server.js

const DataLoader = require('dataloader');
const User = require('../models/User');
const Post = require('../models/Post');

// 创建 DataLoader
const userLoader = new DataLoader(async (keys) => {
  const users = await User.find({ _id: { $in: keys } });
  return keys.map(key => users.find(user => user._id.equals(key)));
});

const postLoader = new DataLoader(async (keys) => {
  const posts = await Post.find({ _id: { $in: keys } });
  return keys.map(key => posts.find(post => post._id.equals(key)));
});

// 创建上下文
const context = {
  userLoader,
  postLoader,
};

module.exports = context;

const userLoader = new DataLoader(async (keys) => {
  const users = await User.find({ _id: { $in: keys } });
  return keys.map(key => users.find(user => user._id.equals(key)));
}, { cache: false });

const userLoader = new DataLoader(async (keys) => {
  try {
    const users = await User.find({ _id: { $in: keys } });
    return keys.map(key => users.find(user => user._id.equals(key)));
  } catch (error) {
    console.error('批量加载用户失败:', error);
    throw error;
  }
});

const resolvers = {
  Query: {
    users: async (_, __, context) => {
      return context.userLoader.loadMany(keys);
    },
  },
};