关于模式缝合的自定义指令

我正在尝试将一个指令添加到一个从远程模式扩展的类型中。

   const extensionSchema = `
    directive @upper on FIELD_DEFINITION
    extend type User {
        firstname: String @upper
    }

`;
    // resolvedSchemas is an array of makeRemoteExecutableSchema coming from introspection queries.
resolvedSchemas.push(extensionSchema);

return mergeSchemas({
    schemas: resolvedSchemas,
    schemaDirectives: {
        upper: UpperCaseDirective
    }
   })

我得到: Error: Unknown directive "upper". 我错过了什么?

我的指示:

const { SchemaDirectiveVisitor } = require("graphql-tools");
const { defaultFieldResolver } = require("graphql");

module.exports = class UpperCaseDirective extends SchemaDirectiveVisitor {
  visitFieldDefinition(field) {
    const { resolve = defaultFieldResolver } = field;
    field.resolve = async function (...args) {
            const result = await resolve.apply(this, args);
            console.log("RESULTADOOOO", result);
      if (typeof result === "string") {
        return result.toUpperCase();
      }
      return result;
    };
  }
}