Extend SchemaDirectiveVisitor To Use Apollo Server Schema Directives in NodeJS

Question

In Apollo Server 2, I'm attempting to extend SchemaDirectiveVisitor in order to create a custom directive. I'm specifically using the 2.2.6 hapi node module.

My server.js code is as follows:

const { ApolloServer } = require('apollo-server-hapi');
const { SchemaDirectiveVisitor } = ApolloServer;

class ViewTemplateGroup extends SchemaDirectiveVisitor {
  visitFieldDefinition(field) {
    console.log('Im calling this directive!');
    return;
  }
}

When I start up my server I immediately get the following error:

TypeError: Class extends value undefined is not a constructor or null
    at Object.<anonymous> (/Users/garrett.kim/Desktop/Projects/Test Web/poc-graphQL-forms-gyk/server.js:36:33)
    at Module._compile (module.js:660:30)
    at Object.Module._extensions..js (module.js:671:10)
    at Module.load (module.js:573:32)
    at tryModuleLoad (module.js:513:12)
    at Function.Module._load (module.js:505:3)
    at Function.Module.runMain (module.js:701:10)
    at startup (bootstrap_node.js:193:16)
    at bootstrap_node.js:617:3

To my knowledge, I'm following the Apollo Server 2 example very closely.

Any assistance in getting commands to work would be greatly appreciated.

Answer 1

Because the ApolloServer class lacks a SchemaDirectiveVisitor property, calling ApolloServer fails. As the problem implies, SchemaDirectiveVisitor returns undefined, therefore a class cannot extend undefined. Simply use the apollo-server-hapi module to import SchemaDirectiveVisitor:

const { ApolloServer, SchemaDirectiveVisitor } = require('apollo-server-hapi')

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