Unable to mutate enum value through visitEnumValue

[danielrearden]

Just hit this issue while trying to implement a simple directive that would let you change the value of an enum value:

export class ValueDirective extends SchemaDirectiveVisitor {
  visitEnumValue(
    enumValue: GraphQLEnumValue,
  ): GraphQLEnumValue {
  return {
    ...enumValue,
    value: this.args.string,
  }  
}

The intent here is to have an SDL-only way to deal with "internal" values of enum values without having to utilize the resolver map.

The issues is that GraphQLEnumType utilizes several private properties that are derived from the initial set of values. I think the entire GraphQLEnumType would need to be recreated with an updated config whenever the visitor is called or after all directives are ran, but off-hand I'm not sure how feasible either approach is.

[yaacovCR]

Good catch, visitEnumValue has been broken since v14, see related issues fixed in ardatan#953 which did not include this fix.

Can you reopen this issue on upstream graphql-tools repository? Fork will soon be deprecated, see ardatan#1308

You can help out also by creating a PR with a failing test!

The fix will involve recreating the entire type with every changed value, as you suggest, see lines around https://github.com/apollographql/graphql-tools/blob/next/src/utils/visitSchema.ts#L200

Feel free to take a stab at it.

Not sure if your intent with this directive is best practice, as it does leak some private implementation details. But sure seems convenient.

[danielrearden]

Excellent! I'm elated to see all this work finally get merged upstream. I'll close this out and open a PR upstream with a failing test when I get a moment.