Apollo DataSource for Firestore


This is a Firestore DataSource for Apollo GraphQL Servers. It was adapted from the CosmosDB DataSource

> Warning\
> Version 6.x and up supports apollo server v4, and, through the nature of
> apollo server v4 it works well with other graphql servers or even standalone.\
> If you need apollo server v3 support, use version 5.x of this package.

Usage

Use by creating a new class extending the FirestoreDataSource,
with the desired document type. Use separate DataSources for each data type,
and preferably different collections in Firestore too. Initialise the class
by passing a collection reference created by the Firestore library.

``typescript
export interface UserDoc {
// a string id value is required for entities using this library.
// It will be used for the firestore document ID but not stored in the document in firestore.
readonly id: string
readonly collection: 'users'
// the createdAt and updatedAt timestamps stored by firestore natively are
// available as properties as well
readonly createdAt: Timestamp
readonly updatedAt: Timestamp
name: string
groupId: number
}

export interface PostsDoc {
readonly id: string
readonly collection: 'posts'
// the createdAt and updatedAt timestamps stored by firestore natively are
// available as properties as well
readonly createdAt: Timestamp
readonly updatedAt: Timestamp
title: string
}

export class UserDataSource extends FirestoreDataStore {}
export class PostsDataSource extends FirestoreDataStore {}

const usersCollection: CollectionReference = firestore.collection('users')
const postsCollection: CollectionReference = firestore.collection('posts')

const server = new ApolloServer({
typeDefs,
resolvers
})

const { url } = await startStandaloneServer(server, {
async context () {
const { cache } = server
return {
// We create new instances of our data sources with each request.
// We can optionally pass in our server's cache, or logger
dataSources: {
users: new UserDataSource(usersCollection, { cache }),
posts: new PostsDataSource(postsCollection, { cache })
}
}
}
})
`

Custom queries

FirestoreDataSource has a findByQuery method that accepts a function taking
the collection as its only argument, which you can then create a query based on.
Can be used in resolvers or to create wrappers.

Example of derived class with custom query methods:

`typescript
export class UserDataSource extends FirestoreDataStore {
async findManyByGroupId (groupId: number) {
return this.findManyByQuery(c => c.where('groupId', '==', groupId).limit(2))
}

async findOneByEmail (email: string) {
return this.findManyByQuery(c => c.where('email', '==', email).limit(1))?.[0] ?? undefined
}
}
`

Write Operations

This DataSource has some built-in mutations that can be used to create, update
and delete documents.

`typescript
await context.dataSources.users.createOne(userDoc)

await context.dataSources.users.updateOne(userDoc)

await context.dataSources.users.updateOnePartial(userId, { name: 'Bob' })

await context.dataSources.users.deleteOne(userId)
`

Batching

Batching is provided on all id-based queries by DataLoader.

Caching

Caching is available on an opt-in basis by passing a ttl` option on queries.