zync-nest-library/libs/src/directives/depth.ts

NestJS library with database backup and file upload utilities

import { getDirective, MapperKind, mapSchema } from "@graphql-tools/utils";
import { defaultFieldResolver, GraphQLSchema } from "graphql";

export function deptLimitDirectiveTransformer(
  schema: GraphQLSchema,
  directiveName: string
) {
  return mapSchema(schema, {
    [MapperKind.OBJECT_FIELD]: (fieldConfig) => {
      const deptLimitDirective = getDirective(
        schema,
        fieldConfig,
        directiveName
      )?.[0];
      if (deptLimitDirective) {
        const { resolve = defaultFieldResolver } = fieldConfig;
        fieldConfig.resolve = async function (source, args, context, info) {
          const result = await resolve(source, args, context, info);
          const { value }: any =
            fieldConfig.astNode.directives[0].arguments[0].value;

          if (Array.isArray(result)) {
            return result.slice(0, +value);
          }
          return result;
        };
        return fieldConfig;
      }
    },
  });
}