keyv-dataloader

A DataLoader implementation with caching support using Keyv. Combines the batching capabilities of Facebook's DataLoader with the flexible caching of Keyv.

Installation

# Install the package (recommended)
pnpm add keyv-dataloader
pnpm add dataloader keyv

# Or with npm
npm install keyv-dataloader
npm install dataloader keyv

# Or with yarn
yarn add keyv-dataloader
yarn add dataloader keyv

Usage

import { KeyvDataLoader } from 'keyv-dataloader';

// Create a new loader with caching
const loader = new KeyvDataLoader({
  // Function to batch load keys
  batchLoadFn: async (keys) => {
    console.log('Loading keys:', keys);
    return keys.map((key) => `Value for ${key}`);
  },
  // Optional: Custom function to generate cache keys
  cacheKeyFn: (key) => `custom-prefix:${key}`,
  // Optional: TTL in milliseconds (how long to keep items in cache)
  ttl: 60 * 1000, // 1 minute
  // Optional: Keyv options (storage adapters, etc.)
  keyvOptions: {
    namespace: 'my-cache',
  },
  // Optional: DataLoader options
  dataLoaderOptions: {
    maxBatchSize: 100,
    cache: true,
  },
});

// Load a single value (returns a Promise)
const value = await loader.load('key1');

// Load multiple values (returns a Promise)
const values = await loader.loadMany(['key2', 'key3']);

// Prime the cache with a value (returns a Promise that resolves to the instance for chaining)
// If the key already exists, no change is made
await loader.prime('key4', 'Value for key4');

// Prime the cache with an error
await loader.prime('key5', new Error('This is an error'));

// Clear a value from cache (returns a Promise that resolves to the instance for chaining)
await loader.clear('key1');

// Clear all cached values (returns a Promise that resolves to the instance for chaining)
await loader.clearAll();

// Sequential calls for forcefully updating a cached value
await loader.clear('key1');
await loader.prime('key1', 'new value');

// Using Promise chaining
loader.clear('key1')
  .then(loader => loader.prime('key1', 'new value'))
  .then(loader => {
    // Continue using the loader...
  });

API

new KeyvDataLoader(options)

Creates a new KeyvDataLoader instance.

Options

• batchLoadFn: Function to batch load multiple keys
• cacheKeyFn (optional): Function to generate cache key from the input key
• ttl (optional): TTL in milliseconds for cache entries
• dataLoaderOptions (optional): DataLoader options
• keyvOptions (optional): Keyv options

Methods

• load(key): Loads a key, returns a Promise for the value
• loadMany(keys): Loads multiple keys, returns a Promise for array of values
• prime(key, value): Prime the cache with a key-value pair. Returns a Promise that resolves to the instance for method chaining. If the key already exists, no change is made. To forcefully prime the cache, clear the key first with sequential calls: await loader.clear(key); await loader.prime(key, value);. To prime the cache with an error, provide an Error instance.
• clear(key): Clear a key from cache. Returns a Promise that resolves to the instance for method chaining.
• clearAll(): Clear all keys from cache. Returns a Promise that resolves to the instance for method chaining.

All methods return Promises. The clear(), clearAll(), and prime() methods resolve to the instance for method chaining, while load() and loadMany() resolve to the loaded values.

Features

• DataLoader Compatible: Implements the same API as Facebook's DataLoader
• Batching: Groups individual loads that occur within a single tick of the event loop into a single batch
• Efficient Caching: Uses Keyv's batch methods (getMany, setMany) for optimal performance
• Redis Storage: Works with Redis storage adapter via Keyv
• TypeScript Support: Fully typed API
• Method Chaining: All methods support Promise-based method chaining

Performance

By leveraging Keyv's batch operations (getMany, setMany), this implementation reduces the number of I/O operations required when working with multiple keys, resulting in better performance compared to individual operations, especially when using Redis.

Testing

The package includes a comprehensive test suite covering Redis storage adapter. See the tests README for detailed instructions on running tests.

# Run all tests
pnpm test

# Run Redis tests only
pnpm test:redis

# Run all tests with Docker (requires Docker and Docker Compose)
pnpm test:docker

# Run tests with coverage
pnpm test:coverage

Development

This project uses changesets for version management and publishing.

# Add a new changeset
pnpm changeset

# Update versions and changelogs
pnpm version

# Publish to npm
pnpm release

License

MIT