GraphQL Directive to Rename a Field from Source to Schema Context

Contact.graphql

directive @fromSourceField(name: String!) on FIELD

"""
This is a Contact type where the data source uses type-specific field names
for their ID fields. In this case we're renaming this field to `id` instead
of `contact_id`, making it much more friendly to the consuming application.
"""
type Contact {
  id: ID! @fromSourceField(name: "contact_id")
  ...
}

FromSourceFieldsDirective.js

import { SchemaDirectiveVisitor } from 'graphql-tools';

export default class FromSourceFieldsDirective extends SchemaDirectiveVisitor {
  visitFieldDefinition(field) {
    // The "name" argument given to the directive, ie `@fromSourceField(name: "contact_id")`
    const { name } = this.args;
    const { defaultFieldResolver } = field;
    field.resolve = async (object, args, context, info) => {
      object[field.name] = object[name];
      return resolve.call(this, object, args, context, info);
    };
  }
}

server.js

// If you're using something like apollo-server, this is how you'd make the directive available:

import { makeExecutableSchema } from 'graphql-tools';
import FromSourceField from './FromSourceField.js';

// import or declare your typeDefs and resolvers - that process depends on your local setup.

const schema = makeExecutableSchema({
  typeDefs,
  resolvers,
  
  // Add your custom directives:
  schemaDirectives: {
    fromSourceField: FromSourceField
  }
});

// Then pass the schema to your server...

It seems this only works when using a resolver and not a plain type. Any hint on how to implement this?

For example, when I return an object in my resolver:

return { contact_id: 'foo' }

with my GraphQL schema:

type Contact {
  id: ID! @fromSourceField(name: "contact_id")
  ...
}

it doesn't work since there is no field.resolve (and when adding one it will be ignored).

@steebchen fix the issue and published a package: https://www.npmjs.com/package/apollo-directives

I am going to try this package out.