Provide more accurate types for apollo-server-expresse's ContextFunction

[cheapsteak]

This was an issue brought up in #1593

This PR should provide more accurate typing information for apollo-server and apollo-server-express

• ContextFunction can return a new context object synchronously
• context for apollo-server and apollo-server-express will contain req and res

TODO:

• Update CHANGELOG.md with your change (include reference to issue & this PR)
• Make sure all of the significant new logic is covered by tests
• Rebase your changes on master so that they can be merged easily
• Make sure all tests and linter rules pass

[abernix]

This looks great!

[abernix]

Me: "Looks great!"
Also me: Accidentally clicks "Request changes".

[abernix]

This has been included in 2.4.3. I plan on promoting it to the latest tag tomorrow, but you can try this right now using the next tag or by directly installing 2.4.3.

[nklayman]

Could you export this as well so it can be used when defining a context type (to be used with strongly-typed resolvers)? Right now I have to do this:

import { User } from 'prisma-client'
import { IncomingMessage } from 'http'

export interface MyContext {
  user: User
  request: {
    res: IncomingMessage
    req: IncomingMessage
  }
}

[cheapsteak]

@nklayman great point
Would this PR by KATT solve that issue? #2352

[nklayman]

Yep, this line should do it.

[cheapsteak]

@nklayman released as 2.4.5
Thanks for surfacing the issue!

[abernix]

@cheapsteak I think bringing this cors property into the ApolloServerExpress config may actually go against the existing patterns for users of apollo-server-express, which I believe has typically asked for cors to be set as part of applyMiddleware.

For example, as #1882 points out, there's a typing issue on the ApolloServer exported from the standalone apollo-server package (which does not require or have applyMiddleware since it's "standalone") that seems to omit the cors property.

While the integrations pass their cors settings via applyMiddleware, the standalone doesn't have applyMiddleware, so it was necessary to provide desired cors settings via the constructor.

Currently, this new typing seems to almost encourage apollo-server-express users to set their cors in the constructor as well, even though all the other integrations require cors to be set in the applyMiddleware. In fact, I don't believe that setting cors via apollo-server-express's ApolloServer constructor would actually work since it's only in the apollo-server implementation that we set this.cors = config && config.cors;.

[cheapsteak]

Great point, appreciate the thorough breakdown
Opened a PR to address this - #2373