Nexus: Why can't specify both nullable and required on an input field?

[santialbo]

Right now it's not possible to set an input type to be both nullable and required. Is there a reason why? I would have expected to be able to do the following:

field: stringArg({}) // -> field: string;
field: stringArg({nullable: true}) // -> field: string | null; actually returning field?: string | null;
field: stringArg({nullable: true, required: false}) // -> field?: string | null;
field: stringArg({required: false}) // -> field?: string;

Am I missing anything?

[gabrielbusarello]

If the field can receive null, that want to say that the field is not required. The nullable and required are opposites.

[santialbo]

I guess my confusion is because of undefined in javascript. I was expecting that if I set the field nullable and required the user of the api would have to explicitly set a value or null. Just omitting the value would result on an error.

[yarikos]

@gabrielbusarello

The nullable and required are opposites.

Generally, they are not mutually exclusive.

This tiny difference could be shown, as an example, in a case of mutation for updateSomething with PATCH semantic, when Something has a nullable field.

In this case undefined means "this request does nothing with the field" and null means "set the field to null".

[Weakky]

Hi folks,

The root problem here is that GraphQL doesn't differentiate _nullability_ from _optionality_. Nullability in GraphQL expresses both concepts, so you can't define a field both required and nullable. There's unfortunately nothing we can really do. Closing now!

[Sytten]

Linked to https://github.com/graphql-nexus/schema/issues/439