add extension.code field to BatchItemNotFoundError

README.md

@@ -1,7 +1,7 @@
 # 🤖 dataloader-codegen
 
 [![npm](https://img.shields.io/npm/v/dataloader-codegen.svg)](https://yarn.pm/dataloader-codegen)
-[![Build Status](https://travis-ci.org/Yelp/dataloader-codegen.svg?branch=master)](https://travis-ci.org/Yelp/dataloader-codegen)
+[![Build Status](https://api.travis-ci.com/Yelp/dataloader-codegen.svg?branch=master)](https://travis-ci.com/github/Yelp/dataloader-codegen)
 
 dataloader-codegen is an opinionated JavaScript library for automagically generating [DataLoaders](https://github.com/graphql/dataloader) over a set of resources (e.g. HTTP endpoints), with a predictable interface, and maintains type safety.
 

src/codegen.ts

@@ -56,6 +56,7 @@ export default function codegen(
         import invariant from 'assert';
         import DataLoader from 'dataloader';
         import {
+            BatchItemNotFoundError,
             CaughtResourceError,
             cacheKeyOptions,
             partitionItems,

src/implementation.ts

@@ -1,10 +1,7 @@
 import { ResourceConfig, BatchResourceConfig, NonBatchResourceConfig } from './config';
 import assert from './assert';
 import { getLoaderTypeKey, getLoaderTypeVal } from './genTypeFlow';
-
-function errorPrefix(resourcePath: ReadonlyArray<string>): string {
-    return `[dataloader-codegen :: ${resourcePath.join('.')}]`;
-}
+import { errorPrefix } from './runtimeHelpers';
 
 function getLoaderComment(resourceConfig: ResourceConfig, resourcePath: ReadonlyArray<string>): string {
     const configComment = JSON.stringify(resourceConfig, null, 2)
@@ -246,7 +243,7 @@ function getBatchLoader(resourceConfig: BatchResourceConfig, resourcePath: Reado
                                     /**
                                     * We must return errors for all keys in this group :(
                                     */
-                                    response = new Error([
+                                    response = new BatchItemNotFoundError([
                                         \`${errorPrefix(
                                             resourcePath,
                                         )} Resource returned \${response.length} items, but we requested \${requests.length} items.\`,

src/runtimeHelpers.ts

@@ -12,10 +12,20 @@ export function errorPrefix(resourcePath: ReadonlyArray<string>): string {
     return `[dataloader-codegen :: ${resourcePath.join('.')}]`;
 }
 
+/**
+ * An error reflects missing item in response. It follows similar structure to ApolloError that has an `extension` field.
+ * This makes it easier to link and integrate with apollo-server
+ * @see https://github.com/apollographql/apollo-server/blob/faba52c689c22472a19fcb65d78925df549077f7/packages/apollo-server-errors/src/index.ts#L3
+ */
 export class BatchItemNotFoundError extends Error {
+    readonly extensions: Record<string, any>;
+
     constructor(message: string) {
         super(message);
         this.name = this.constructor.name;
+        this.extensions = {
+            code: 'BATCH_ITEM_NOT_FOUND_ERROR',
+        };
         Error.captureStackTrace(this, this.constructor);
     }
 }