Allow usage of formats other than JSON?

[dancojocaru2000]

Although "the GraphQL spec does not require it", there doesn't seem a way to use anything other than JSON with this. Is there any plan to allow a custom format to be used?

[SamMaxwell]

My project uses express-graphql and I require it to support export to xlsx, csv and pdf. It would be quite easy, if express-graphql provided a way to override or extend the sendResponse function. For now I have to override the express response object in middleware.