Unable to mutate enum value through visitEnumValue

[danielrearden]

I 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 with the above directive is to have an SDL-only way to deal with "internal" values of enum values without having to utilize the resolver map.

Like all the other visitors, visitEnumValue lets you return a new GraphQLEnumValue that should replace the existing enum value. However, GraphQLEnumType utilizes several private properties that are derived from the initial set of values so just replacing the enum value won't cut it -- the whole enum type has to be created if any of the values are modified.

[yaacovCR]

Thanks for this PR, try out with npm install graphql-tools@alpha.

[danielrearden]

Works like a charm, thank you for the quick turnaround!

[yaacovCR]

Closed by #1419.