@mavenoid/dataloader

@mavenoid/dataloader

Utilities for caching, batching and deduping requests in GraphQL. Inspired by dataloader but extended using WeakMap to create a more convenient API for GraphQL

Installation

yarn add @mavenoid/dataloader

Usage

import {
  getDataLoadersForContextType,
  RequestsBatch,
} from '@mavenoid/dataloader';

const {batch, dedupe} = getDataLoadersForContextType<ResolverContextType>();

export const getUserDeduped = dedupe(
  async (userID: number, resolverContext: ResolverContextType) => {
    return await getUserUncached(userID);
  },
);

// You can load a user within a GraphQL resolver using:
//
//   getUserDeduped(userID, resolverContext)
//
// You can call this as many times as you like, and `getUserUncached` will only be called
// once per request.
//
// if you modify a user within a request, you can delete it from the cache using:
//
//   getUserDeduped.cache(resolverContext).delete(userID)
//
// or
//
//   getUserDeduped.cache(resolverContext).clear()

const getUserBatched = batch(
  async (req: RequestsBatch<number, User | null>) => {
    const users = await db_users.find({id: anyOf([...req.keys()])}).all();
    for (const user of users) {
      const resolvers = req.get(user.id);
      if (resolvers) {
        resolvers.resolve(user);
      }
    }
    return null;
  },
  {maxBatchSize: 100},
);

// You can load a user within a GraphQL resolver using:
//
//   getUserBatched(userID, resolverContext)
//
// You can call this as many times as you like, and the database will only be queried
// once per request. The requests will be batched so that up to 100 users are loaded
// at a time.
//
// if you modify a user within a request, you can delete it from the cache using:
//
//   getUserBatched.cache(resolverContext).delete(userID)
//
// or
//
//   getUserBatched.cache(resolverContext).clear()