@mercuriusjs/federation

A module to add Apollo Federation v1 metadata info to a schema.

Quick start

``bash
npm i fastify @mercuriusjs/federation
`

`js
const Fastify = require('fastify')
const { mercuriusFederationPlugin } = require('@mercuriusjs/federation')

const users = {
1: {
id: '1',
name: 'John',
username: '@john'
},
2: {
id: '2',
name: 'Jane',
username: '@jane'
}
}

const app = Fastify()
const schema =
extend type Query {
me: User
}

type User @key(fields: "id") {
id: ID!
name: String
username: String
}

const resolvers = {
Query: {
me: () => {
return users['1']
}
},
User: {
__resolveReference: (source, args, context, info) => {
return users[source.id]
}
}
}

app.register(mercuriusFederationPlugin, {
schema,
resolvers
})

app.get('/', async function (req, reply) {
const query = '{ _service { sdl } }'
return app.graphql(query)
})

app.listen({ port: 3000 })
`

$3

Instead of using the plugin, the federation schema can be built using the buildFederationSchema function and passing the schema generated to mercurius.

`javascript
const Fastify = require('fastify')
const mercurius = require('mercurius')
const { buildFederationSchema } = require('../')

...

app.register(mercurius, {
schema: buildFederationSchema(schema),
resolvers,
graphiql: true
})

...
`

API

$3

A fastify plugin to create a mercurius server that expose the federation directives.

`javascript
const { mercuriusFederationPlugin } = require('@mercuriusjs/federation')

const schema = ...
const resolvers = ...
const app = Fastify()

app.register(mercuriusFederationPlugin, {
schema,
resolvers
})
`

#### options
Uses the same options of mercurius but
it requires a string, DocumentNode or an Array of DocumentNode for schema attribute.

$3

Create a schema object that can be used in a federated environment

(schema, opts) => GraphQLSchema

- schema string | DocumentNode | Array: the source schema
- opts object:
- isGateway boolean: If enabled create a schema compatible with the gateway`, Default 'false'