mapSchema() wipes out federated schema resolveReference() function

[robross0606]

Describe the bug
When applying mapSchema() to a federated schema, any resolveReference functions on types are wiped out.

To Reproduce
The following Jest test shows that even a NooP transform using mapSchema() wipes out the federated resolveReference function.

const gql = require('graphql-tag')
const { mapSchema } = require('@graphql-tools/utils')
const { buildFederatedSchema } = require('@apollo/federation')

test('mapSchema() wipes out resolveReference function', async () => {
  const federatedEntity = gql`
    type FederatedEntity @key(fields: "id") {
      id: ID!
      properties: [String!]!
    }
  `
  const federatedEntityResolver = {
    FederatedEntity: {
      __resolveReference: async object => {
        object.properties = ['a', 'couple', 'of', 'properties']
        return object
      }
    }
  }

  let schema = buildFederatedSchema([
    {
      typeDefs: federatedEntity,
      resolvers: federatedEntityResolver
    }
  ])

  // Confirm that federated `resolveReference` function exists.
  expect(schema._typeMap.FederatedEntity.resolveReference).toBeTruthy()

  // NooP transform
  const mappedSchema = mapSchema(schema)

  // This should pass but it fails because `resolveReference` has been wiped out.
  expect(mappedSchema._typeMap.FederatedEntity.resolveReference).toBeTruthy()
})

Expected behavior
One would expect mapping a schema should pass thru anything not specifically mapped.

Environment:

• OS: Tested on Windows 10 and multiple flavors of Linux
• @graphql-tools/utils: 7.5.0
• NodeJS: 14.15.5

[ardatan]

Thanks for the reporting this missing feature. Would you create a draft PR then we can help you?

[robross0606]

Thanks for the reporting this missing feature. Would you create a draft PR then we can help you?

Unfortunately, I don't have the bandwidth or background on your code base to fix this issue. I know it is happening, but not why.

[rajagopalx]

Is there any workaround for this?

[yaacovCR]

The fix would be for Apollo federation to use extensions to extend the schema with metadata instead of custom properties. A workaround would involve copying the custom federation stuff like resolveReference and whatever else from the old schema to the mapped schema...

[yaacovCR]

This is not a bug in graphql tools. It is a feature request to handle the custom GraphQLSchema objects created by Apollo...

we could try to do that, but we would need to investigate what hidden metadata they are using. It’s not our code base that you need to be familiar with to help fix this, it’s Apollo’s...

[kkckkc]

I understand that this is not an issue with graphql-tools per se, but I really need this - with the slight difference in that I'm interested in resolveObject instead of resolveReference.

I have a simple patch to fix my immediate issue, i.e. propagating these two fields as part of mapSchema and wrapSchema - but I haven't looked at the full potential scope of this issue across all functionality.

Should I submit a PR?

[yaacovCR]

Sure, thanks!!! We love PRs :)

[robross0606]

I just found this same exact issue occurs if you use const { addResolversToSchema } = require('@graphql-tools/schema'). Calls to that function completely wipe out Aopllo Federation resolvers.

[ardatan]

@robross0606 You can use updateResolversInPlace flag to avoid recreation of the schema.

[MrDesjardins]

I am having the same issue. When I and using buildSubgraphSchema + mapSchema the resolveReference is out.

[ShawnWilsonCB]

Is there any workaround at all for this?

[a7ul]

There is a workaround here https://community.apollographql.com/t/are-object-resolvers-broken-with-custom-schema-directives/1578/4

[trevor-scheer]

#2857 (comment)

@ardatan I think this issue can be closed out as well.