GraphQL Server

You can run a full GraphQL Yoga server inside an Nhost Function. This is useful for creating Hasura Remote Schemas — extending your GraphQL API with custom types and resolvers without running a separate service.

Dependencies

npm install graphql graphql-yoga

Function

Create a file at ./functions/remote-schema.ts:

import type { Request, Response } from 'express'
import { createSchema, createYoga } from 'graphql-yoga'

const typeDefs = `
  type Query {
    hello: String!
  }
`

const resolvers = {
  Query: {
    hello: () => 'world',
  },
}

const schema = createSchema({ typeDefs, resolvers })

const yoga = createYoga({
  schema,
  graphqlEndpoint: '*',
})

export default async function handler(req: Request, res: Response) {
  const url = `${req.protocol}://${req.get('host')}${req.originalUrl}`

  const response = await yoga.fetch(url, {
    method: req.method,
    headers: req.headers as HeadersInit,
    body: req.method !== 'GET' ? JSON.stringify(req.body) : undefined,
  })

  res.status(response.status)
  response.headers.forEach((value, key) => {
    res.setHeader(key, value)
  })

  const body = await response.text()
  res.send(body)
}

Setting graphqlEndpoint: '*' tells Yoga to handle requests at any path, which is necessary because the function’s URL is determined by its file location.

Adding as a Hasura Remote Schema

Once deployed, you can add the function as a remote schema in Hasura. Point Hasura to the function’s endpoint:

{{NHOST_FUNCTIONS_URL}}/remote-schema

Use the NHOST_ADMIN_SECRET environment variable or a forwarded authorization header to secure the connection.