Hi @Debiday. Glad to see you going through the article and learning about Dgraph and GraphQL!
The mutation is failing in your case because Dgraph generates those ids automatically, and they’re unique. They aren’t going to be the same as they were in my case.
That’s why we did a queryPost to find out what ids Dgraph generated for us. Then we can go ahead and use them.
Hope this helps. Feel free to ask any questions you may have.