⚡️ GraphQL Cached

Write a cache layer for each resolver in GraphQL Shield style with Memcached

Dependencies

• Memcached
• GraphQL Middleware
• Your GraphQL Schema

Install

$ yarn add graphql-cached

Usage

with graphql-tools

import { cached } from 'graphql-cached'
import { applyMiddleware } from 'graphql-middleware'
import Memcached from 'memcached'
import schema from './schema'

const memcached = new Memcached('my.memcached.host:11211')

// Generated resolver types by `@graphql-codegen/cli`
import { Resolvers } from './__generated__/resolvers'
import { Context } from './context'

const middleware = cached<Context, Resolvers>(
  {
    User: {
      image: {
        key(parent, args, context) {
          // it's type-safe!
          return parent.imageId
        },
        lifetime: 5,
        serializer: {
          serialize(item) {
            return item
          },
          deserialize(serializedItem) {
            return new Image(serializedItem)
          },
        },
      },
    },
  },
  {
    memcached,
    contextKey(context) {
      return 'v1.' + context.user?.role || 'Anonymous'
    },
  }
)

// Now schema is automatically cached!
const cachedSchema = applyMiddleware(schema, middleware)

Cache Field

Required

• key: fieldKey generation function

Optional

• lifetime: How much time to keep the cache (seconds) (default: 10 seconds)
• serializer: Preprocess item before storing in cache and after fetching from cache

Configuration

Required

• memcached: Memcached client instance
• contextKey: Key generation function based on Context

Life cycle hooks (Optional)

• beforeGet: Triggered before cache fetching
• afterGet: Triggered after cache fetching
• beforeSave: Triggered before cache storing
• afterSave: Triggered before cache storing
• onHit: Triggered when cache hit
• onMiss: Triggered when cache miss

Full cache key

{contextKey}${typeName}${fieldName}${fieldKey}

Examples

v1.Admin$User$image$dbf66e27-9bb4-5682-b890-ecf34fe63333

v1.User$Query$user${"where":{"id":"57c5fb3f-a5e7-5b4f-a7ed-ab50281b8222"}}

⚠️ Be careful!

If there are resolvers with different responses for different users, carefully write the key generation function. Items cached for one user may be visible to other users.

Also, if there is a cached item, the existing resolver does not work. If you want to do permission-related logic before cache layer, I recommend using it with graphql-shield.

const schemaWithMiddleware = applyMiddleware(
  schema,
  authMiddleware, // created with graphql-shield
  cachedMiddleware // created with graphql-cached
)

For more information on how GraphQL Middleware works, check out GraphQL Middleware.

Usage examples

• with-graphql-tools
• with-nexus

If you have a feature request or a bug, please create a new issue. And also, pull requests are always welcome🙏