Rationale for the "defaultValueInvalidOnNonNullVariable" validation about graphql-ruby HOT 2 CLOSED

Hey, thanks for asking. It was probably mistakenly added a long time ago 🙈 . I bet nobody has reported the problem since it can be worked around by removing the !.

Thanks for linking the relevant spec, @benjie -- I agree, removing it sounds like the right way forward.

from graphql-ruby.

I can confirm that my understanding of the spec suggests this:

query MyQuery($skip: Boolean! = true) {
  __typename @skip(if: $skip)
}

is a valid query for any GraphQL schema, even with no variables provided.

CoerceVariableValues in the spec details what happens when there's a default value but no supplied value:

3.g. If hasValue is not true and defaultValue exists (including null):
3.g.i. Add an entry to coercedValues named variableName with the value defaultValue.

As far as I am aware, there is no rule in the spec forbidding a defaultValue on a non-null variable, nor on arguments nor on input fields. These positions are "required" if they are a non-nullable type and they have no default. Giving them a default makes them "optional" (they're also optional if they are nullable).

from graphql-ruby.