Do not create globalTypes.ts when it is empty

[paulmelnikow]

Fix #2080

Alternative to #2055

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

*Make sure changelog entries note which project(s) has been affected. See older entries for examples on what this looks like.

[paulmelnikow]

The Node 8 and 10 builds are failing with TypeErrors that are generated somewhere in the config system. I can't reproduce these locally (even when using Node 8 or 10). Any idea what might be causing these?

    TypeError [ERR_INVALID_ARG_TYPE]: The "warning" argument must be one of type Error or string

      at Config.warn (../../node_modules/@oclif/config/lib/config.js:310:21)
      at Promise.all.map (../../node_modules/@oclif/config/lib/config.js:135:26)

[natterstefan]

Hi 👋,

is there any chance (@maintainers) that we can take a look at this issue?

It would also help if the file just has an empty export export {} in that case (would fix #1179).

[EyMaddis]

I tried it on my project and it did not work.
Custom scalars will end up in context.typesUsed, but won't be in the globals file but instead will be handled by --customScalarsPrefix, for me there is a Guid scalar I define as string

EDIT: I think this is a simple fix:

import { isScalarType } from 'graphql'
...
const usedTypes = context.typesUsed.filter(t => !isScalarType(t))
            if (usedTypes.length > 0) {
....

Just to be clear: I am not a maintainer. Maybe @abernix can help :)

[EyMaddis]

context.typesUsed.filter(t => !isScalarType(t)).length > 0
to avoid custom scalar types

[paulmelnikow]

Happy to make this change, though it should probably have a test. What's the behavior you're looking for, exactly?

[EyMaddis]

Custom scalars like (in schema terms): scalar MyCustomScalar are inside this array of typesUsed. However, these do not generate anything in the globals files since the generator does can not know what the data structure is actually. This would still leading to an empty file.

https://www.apollographql.com/docs/apollo-server/schema/custom-scalars/

The test scenario would require a custom scalar type and a query that does not use any enums or other globals, but returns the custom scalar.

[paulmelnikow]

Thanks. I added the check in 6d42e81.

[macrozone]

its important that this gets merged, it leads to completily pointless problems that could easily be avoided.