From 7ea4514ecbc7935726c83a0b6cc88a8029427d23 Mon Sep 17 00:00:00 2001
From: axe312ger <opensource@axe312.dev>
Date: Fri, 25 Mar 2022 15:46:28 +0100
Subject: [PATCH] feat: throw error on reservated field names

---
 .../src/create-schema-customization.js                     | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/packages/gatsby-source-contentful/src/create-schema-customization.js b/packages/gatsby-source-contentful/src/create-schema-customization.js
index 155a34a553dbf..084d5210059c2 100644
--- a/packages/gatsby-source-contentful/src/create-schema-customization.js
+++ b/packages/gatsby-source-contentful/src/create-schema-customization.js
@@ -527,6 +527,13 @@ export async function createSchemaCustomization(
         if (field.disabled || field.omitted) {
           return
         }
+        if ([`id`, `sys`, `contentfulMetadata`].includes(field.id)) {
+          // Throw error on reserved field names as the Contenful GraphQL API does:
+          // https://www.contentful.com/developers/docs/references/graphql/#/reference/schema-generation/fields
+          throw new Error(
+            `Unfortunately the field name ${field.id} is reserved. ${contentTypeItem.name}@${contentTypeItem.sys.id}`
+          )
+        }
         fields[field.id] = translateFieldType(field, schema, createTypes)
       })