Async scalar – possible?

[borekb]

I'm not sure if this is for GraphQL itself (graphql-js) or graphql-tools but is it possible to do these?

• Async validation
• Having a "resolver" behind a scalar, with access to a configured RESTDataSource like our other resolvers?

Scalars are defined in the resolver map but feel quite different.

[ardatan]

In terms of graphql-js, it is not possible. So graphql-tools uses graphql-js then it is not on our side as well.
Maybe it would be better to do this feature request on graphql-js repo.

[borekb]

Yep. I'm wondering how common this is.

For example, we have a custom scalar MonetaryAmount which is basically a Float but we always want to apply rounding to it, and the rounding rules are defined by the backend so we need to issue an async request via RESTDataSource or similar.

Async validation would be another example – I would assume that calling a backend would also be pretty common during validation..

[borekb]

Discussion in the graphql-js repo: graphql/graphql-js#2663.

[borekb]

@ardatan One piece of feedback from that discussion, which I think is valid, is that graphql-tools mix resolvers and scalars in a resolver map. That is a bit confusing as custom scalar definitions are not resolvers.