Version: Legacy

Schema Directives

GraphQL Modules allows you to define schema directives on a per-module basis. For example, we can add a schema directive to our module like this:

import { GraphQLModule } from '@graphql-modules/core';
import { SchemaDirectiveVisitor } from 'graphql-tools';

const typeDefs = gql`
  directive @date on FIELD_DEFINITION

  scalar Date

  type Query {
    today: Date @date
  }
`;
const resolvers = {
  Query: {
    today: () => new Date();
  },
};

class FormattableDateDirective extends SchemaDirectiveVisitor {
  public visitFieldDefinition(field) {
    const { resolve = defaultFieldResolver } = field;

    field.args.push({
      name: 'format',
      type: GraphQLString,
    });

    field.resolve = async function (source, args, context, info) {
      const date = await resolve.call(this, source, args, context, info);
      return date.toLocaleDateString();
    };

    field.type = GraphQLString;
  }
}

const schemaDirectives = {
  date: FormattableDateDirective
};

const { schema } = new GraphQLModule({
  typeDefs,
  resolvers,
  schemaDirectives,
});

GraphQL Modules won't automatically apply your directives when it generates a schema for a module to avoid applying the same directive more than once. However, you can set the visitSchemaDirectives option to true in your root module and the directives from all your combined modules will be applied to your final schema.

const { schema } = new GraphQLModule({
  typeDefs,
  resolvers,
  schemaDirectives,
  visitSchemaDirectives: true,
});