apollo graphql upper directive

upperDirective.ts

/**
 * Copyright (c) 2023-present, Bruno Carvalho de Araujo.
 * All rights reserved.
 *
 * This source code is licensed under the license found in the LICENSE file in
 * the root directory of this source tree.
 */

import { getDirective, MapperKind, mapSchema } from '@graphql-tools/utils'
import { defaultFieldResolver, type DocumentNode, type GraphQLSchema } from 'graphql'
import gql from 'graphql-tag'

type DirectiveReturn = {
  transformSchema: (schema: GraphQLSchema) => GraphQLSchema,
  typeDefs: DocumentNode
}

export function upperDirective (directiveName: string = 'upper'): DirectiveReturn {
  return {
    typeDefs: gql`
      directive @${directiveName} on FIELD_DEFINITION
    `,
    transformSchema: schema => mapSchema(schema, {
      [MapperKind.OBJECT_FIELD]: fieldConfig => {
        const upperDirective = getDirective(schema, fieldConfig, directiveName)?.[0]

        if (!upperDirective) {
          return undefined
        }

        const { resolve = defaultFieldResolver } = fieldConfig

        return {
          ...fieldConfig,
          resolve: async (source, args, context, info) =>  {
            const result = await resolve(source, args, context, info)

            if (typeof result === 'string') {
              return result.toUpperCase()
            }

            return result
          }
        }
      }
    })
  }
}