How to create two subschema configs with transforms basing on the same schema source?

[wadamek65]

I would like to introspect a schema twice to create two subschema configs: one of which I would like to delegate some fields/resolvers to and the other that is exposed in the stitched schema. Introspecting the schema and creating a subschema twice seems to throw transform errors for some reason. This is the error I'm getting in GraphQL response:

The TransformObjectFields transform's  \"transformRequest\" and \"transformResult\" methods cannot be used without first calling \"transformSchema\".

Code of subschema config creation and it's usage:

export async function createContentStoreSubSchemaConfig(
	filterOperations = true
): Promise<SubschemaConfig> {
	const contentStoreSchema = await introspectSchema(contentStoreExec, {
		headers: {
			contentStoreAuthorization: `Bearer ${process.env.GQL_INTROSPECTION_TOKEN}`
		}
	})
	const retypeField = retypeFieldFactory(contentStoreSchema)
	return {
		schema: contentStoreSchema,
		executor: contentStoreExec,
		transforms: [
			new TransformObjectFields(retypeField),
			new RenameTypes(renameType),
			new TransformInterfaceFields(makeFieldNonNull),
			new TransformObjectFields(makeFieldNonNull),
			new TransformObjectFields(makeStringFieldEnum),
			...(filterOperations
				? [
						new FilterRootFields((operation, rootFieldName) => {
							return [
								'entry',
								'sites',
								'save_slides_slide_Entry',
								'save_productSections_productSection_Entry',
								'assets'
							].includes(rootFieldName)
						})
				  ]
				: []),
			new PruneSchema({skipUnusedTypesPruning: true})
		]
	}
}

Usage:

	const fullContentStoreSubSchemaConfig = await createContentStoreSubSchemaConfig(false) // This we use in internal resolvers to delegate to
	const filteredContentStoreSubSchemaConfig = await createContentStoreSubSchemaConfig() // This we would like to expose in the stitched server

[ardatan]

Could you share a reproduction CodeSandbox or repo? Thanks.

[wadamek65]

I didn't make a reproduction, but I managed to create a workaround I think. Instantiating the TransformObjectFields classes more than once seems to produce that error. When I changed the above code to the one below, it started to work properly. I looked into the transform source code and tried debugging but wasn't sure why this would occur. Some kind of prototype creation bug perhaps? The new instatiated transformers didn't have the transformer property which caused this error.

const transforms = [
	new RenameTypes(renameType),
	new TransformInterfaceFields(makeFieldNonNull),
	new TransformObjectFields(makeFieldNonNull),
	new TransformObjectFields(makeStringFieldEnum)
]
export async function createContentStoreSubSchemaConfig(pruned = false): Promise<SubschemaConfig> {
	const contentStoreExec = makeRemoteExecutor(
		process.env.CONTENT_STORE_ENDPOINT,
		'contentStoreAuthorization',
		'userStoreAuthorization'
	)
	const contentStoreSchema = await introspectSchema(contentStoreExec, {
		headers: {
			contentStoreAuthorization: `Bearer ${process.env.CONTENT_STORE_INTROSPECTION_TOKEN}`
		}
	})
	const retypeField = retypeFieldFactory(contentStoreSchema)

	return {
		schema: contentStoreSchema,
		executor: contentStoreExec,
		transforms: [
			...(pruned
				? [
						new FilterRootFields((_, rootFieldName) =>
							[
								'entry',
								'save_productSections_productSection_Entry',
								'assets',
								'save_slides_slide_Entry'
							].includes(rootFieldName)
						),
						new TransformObjectFields(retypeField)
				  ]
				: []),
			...transforms,
			new PruneSchema({skipUnusedTypesPruning: true})
		]
	}
}