Support async schema

[moimael]

• has-reproduction
• feature
• docs
• blocking
• good first issue

Hi,

I tried to migrate our graphql proxy to apollo-server v2 and got an issue reported by TS. We are creating the schema manually (for schema stitching) and make use of the makeRemoteExecutableSchema function. We chose to introspect the schema at runtime so our returned schema is async. It used to work perfectly fine with v1 but now the ApolloServer schema option is not accepting it anymore.

It does work if I wait for my schema to resolve first and then setup the server but it's not very nice.

Could we add support for async schema back ?

Thanks !

[sbrichardson]

One option is to extend the ApolloServer class with a customized applyMiddleware method.
I was able to resolve for the time being using this strategy. See an example in this comment:

#1308 (comment)

In the example, you can't see async/await, but it is resolving a promise behind the scenes.

[sbrichardson]

Here's a more complete example with the playground code included.
I omitted a few details from my own logic, noted below.

It's basically building a custom schema on each request from a cache, instead of just passing the schema from the ApolloServer class instance when it started initially. This isn't using subscriptions currently, I haven't needed/tested with that yet.

import { renderPlaygroundPage } from '@apollographql/graphql-playground-html'
import accepts from 'accepts'
import { ApolloServer, makeExecutableSchema } from 'apollo-server-express'
import { graphqlExpress } from 'apollo-server-express/dist/expressApollo'

class CustomServer extends ApolloServer {
  applyMiddleware({ app, path }) {
    app.use(path, async (req, res, next) => {
      if (this.playgroundOptions && req.method === 'GET') {
        // perform more expensive content-type check only if necessary
        // XXX We could potentially move this logic into the GuiOptions lambda,
        // but I don't think it needs any overriding
        const accept = accepts(req)
        const types = accept.types()
        const prefersHTML =
          types.find(x => x === 'text/html' || x === 'application/json') ===
          'text/html'

        if (prefersHTML) {
          const playgroundRenderPageOptions = {
            endpoint: path,
            subscriptionEndpoint: this.subscriptionsPath,
            ...this.playgroundOptions,
          }
          res.setHeader('Content-Type', 'text/html')
          const playground = renderPlaygroundPage(playgroundRenderPageOptions)
          res.write(playground)
          res.end()
          return
        }
      }

      const {
        // ...omitted for example
      } = req.body

      const { schema: _remove, context: _context, ...serverObj } = this

      return graphqlExpress(
        super.createGraphQLServerOptions.bind({
          ...serverObj,
          graphqlPath: path,
          schema: await makeExecutableSchema(
            // ...omitted for example
          ),
          context: {
            // ...omitted for example
            request: req,
          },
        })
      )(req, res, next)
    })
  }
}

export default CustomServer

[moimael]

Would love to have that, it is currently making the upgrade painful

EDIT: Also it doesn't reload the schema when the schema change since it's resolved before the server starts so you have to restart the server

[jbaxleyiii]

@moimael initial support this is in progress and will also be part of Apollo Server 3.0!