@matters/apollo-response-cache
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Caching and invalidation mechanisms (plugins, directives) of Apollo GraphQL
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# apollo-response-cache
  [](http://commitizen.github.io/cz-cli/)
Caching and invalidation mechanisms (plugins, directives) of Apollo GraphQL, used by [`matters-server`](https://github.com/thematters/matters-server).
[`responseCachePlugin`](./src/plugins/responseCachePlugin.ts) is forked from [`apollo-server-plugin-response-cache`](https://github.com/apollographql/apollo-server/tree/29322ffb8ccf2a07390465d63a2ba16df5603876/packages/plugin-response-cache).
### How it works?
On each query request,
1. `responseCachePlugin` creates an empty key set, and injects it to the context.
2. `@logCache` collects nodes on its field, then add to the key set.
3. `responseCachePlugin` writes query response cache (`fqc`) and node-fqc key mapping to in-memory data store.
Once a mutation updates this node, `@purgeCache` will purge related `fqc`.
### Usage
*Note: there are breaking changes in API from 1.4.0 to 2.0.0, see below Breaking changes section for more info*
Install package:
```bash
npm i @matters/apollo-response-cache
```
Add plugin and directives to the constructor:
```ts
import {
logCacheDirective,
purgeCacheDirective,
responseCachePlugin,
} from '@matters/apollo-response-cache'
const {typeDef: logCacheDirectiveTypeDef, transformer: logCacheDirectiveTransformer} = logCacheDirective()
const {typeDef: purgeCacheDirectiveTypeDef, transformer: purgeCacheDirectiveTransformer} = purgeCacheDirective()
let schema = makeExecutableSchema({
typeDefs: [yourTypeDef, logCacheDirectiveTypeDef, purgeCacheDirectiveTypeDef]
})
schema = logCacheDirectiveTransformer(
purgeCacheDirectiveTransformer(schema)
)
const server = new ApolloServer({
schema,
plugins: [responseCachePlugin()],
})
```
Use in the schema:
```graphql
type Query {
article(id: ID!): Article! @logCache(type: "Article")
}
type Mutation {
archiveArticle(id: ID!): Article! @purgeCache(type: "Article")
}
```
You can also purge cache in the resolver:
```ts
const schema = makeExecutableSchema({
schemaDirectives: {
purgeCache: PurgeCacheDirective({ extraNodesPath: '__invalid_nodes__' }),
},
})
const resolvers = {
Mutation: {
archiveArticle: (parent, args, context) => {
// ...
article.__invalid_nodes__ = [
{
id: '2',
type: 'Article',
},
{
id: '3',
type: 'Comment',
},
]
return article
},
},
}
```
#### Customize node type & id resolvers
You might want a custom function to resolve node's type and id since it may be a `union` or `interface` type.
```ts
const typeResolver = (type: string, result: any) => {
if (['Node', 'Response'].indexOf(type) >= 0) {
return result.__type
}
return type
}
const idResolver = (type: string, result: any) => {
if (['Node', 'Response'].indexOf(type) >= 0) {
return result.__unusual_id__
}
return result.id
}
const schema = makeExecutableSchema({
schemaDirectives: {
purgeCache: PurgeCacheDirective({ typeResolver, idResolver }),
},
})
```
### Breaking changes in 2.0.0
1. Support apollo-server v4 now, but drop support for apollo-server v3 and graphql-tools v8 and below
2. All APIs, including plugin option, directives, helpers interface, changed：
a. pulgin constructor take redis client (type `Redis` from ioredis) instead of `RedisCache` from deprecated apollo-server-cache-redis
b. invalidateFQC take redis instead of `RedisCache`
c. directives api is totally changed to function way, as graphql-tools/utils v8 depreacated class base SchemaDirectiveVisitor
### Known issues
If hit `Types have separate declarations of a private property '__identity'` when build apollo server codebase, make sure both direct dependency on `@apollo/server` and this package dependency on `@apollo/server` share totally same version.
### TODOs
- [x] responseCachePlugin
- [x] @logCache
- [x] @purgeCache
- [ ] Unit Test