Minimalist reproduction of Hasura Issue 8522.

We have a one-to-one relationship between a person and their (postal) address.

Doing an idempotent nested insert fails.

Getting started

Spin up the Docker containers with:

make start

In another tab, launch the Console UI with:

make console

The Mutation

In the GraphiQL playground, run the following mutation, which attempts to do a nested insert, first creating the Person, followed by their postal Address.

The client provides the Person's ID as an idempotency key. This allows clients to safely retry requests without accidentally performing the same operation twice.

mutation CreatePersonWithAddress {
  insertPerson(
    objects: [
      {
        id: "d86eeb43-536c-46d7-832d-d4e1f9480509"
        name: "John Doe"
        address: {
          data: {
            regionCode: "US"
          }
          onConflict: {
            constraint: address_pkey
            update_columns: [id]
          }
        }
      }
    ]
    onConflict: {
      constraint: person_pkey
      update_columns: [id]
    }
  ) {
    returning {
      id
      name
      address {
        regionCode
      }
    }
  }
}

The Error

"cannot insert object relationship ... as ... column values are already determined"

{
  "errors": [
    {
      "extensions": {
        "code": "validation-failed",
        "path": "$.selectionSet.insertPerson.args.objects[0].address"
      },
      "message": "cannot insert object relationship \"address\" as \"id\" column values are already determined"
    }
  ]
}

Workarounds

Workaround 1: Remove the ID

If we remove the idempotency key, and let the database generate the primary key, the error goes away.

Workaround 2: Flatten the inserts

Instead of doing a nested insert, we can do a flat insert and still preserve atomicity:

mutation CreatePersonAndAddress {
  people: insertPerson(
    objects: [
      {
        id: "85e76ace-17d8-4134-ba4f-67c86ba5c7bc"
        name: "John Doe"
      }
    ]
    onConflict: {
      constraint: person_pkey
      update_columns: [id]
    }
  ) {
    returning {
      id
      name
    }
  }
  
  addrs: insertAddress(
    objects: [
      {
        regionCode: "US"
        personId: "85e76ace-17d8-4134-ba4f-67c86ba5c7bc"
      }
    ]
    onConflict: {
      constraint: address_pkey
      update_columns: [id]
    }
  ) {
    returning {
      regionCode
    }
  }
}