oneoff

error_response.json

{
  "errors": [
    {
      "message": "Cannot query field \"isOneOf\" on type \"__Type\".",
      "extensions": {
        "code": "INVALID_GRAPHQL",
        "stacktrace": [
          "GraphQLError: Cannot query field \"isOneOf\" on type \"__Type\".",
          "    at Object.err (/Users/mac/Desktop/oneoff/supergraph/node_modules/@apollo/federation-internals/dist/error.js:11:32)",
          "    at validate (/Users/mac/Desktop/oneoff/supergraph/node_modules/@apollo/federation-internals/dist/operations.js:15:46)",
          "    at selectionOfNode (/Users/mac/Desktop/oneoff/supergraph/node_modules/@apollo/federation-internals/dist/operations.js:2386:13)",
          "    at selectionSetOfNode (/Users/mac/Desktop/oneoff/supergraph/node_modules/@apollo/federation-internals/dist/operations.js:2366:24)",
          "    at selectionOfNode (/Users/mac/Desktop/oneoff/supergraph/node_modules/@apollo/federation-internals/dist/operations.js:2389:19)",
          "    at selectionSetOfNode (/Users/mac/Desktop/oneoff/supergraph/node_modules/@apollo/federation-internals/dist/operations.js:2362:43)",
          "    at parseSelectionSet (/Users/mac/Desktop/oneoff/supergraph/node_modules/@apollo/federation-internals/dist/operations.js:2472:26)",
          "    at operationFromAST (/Users/mac/Desktop/oneoff/supergraph/node_modules/@apollo/federation-internals/dist/operations.js:2456:55)",
          "    at operationFromDocument (/Users/mac/Desktop/oneoff/supergraph/node_modules/@apollo/federation-internals/dist/operations.js:2448:12)",
          "    at /Users/mac/Desktop/oneoff/supergraph/node_modules/@apollo/gateway/dist/index.js:78:100"
        ]
      }
    }
  ]
}

subgraph.mjs

import { ApolloServer } from '@apollo/server'
import { startStandaloneServer } from '@apollo/server/standalone'
import { parse } from 'graphql'
import { buildSubgraphSchema } from '@apollo/subgraph' // added for federation

const typeDefs = parse(`#graphql
  directive @oneOf on INPUT_OBJECT

  type Query {
    users(where: UserWhere!): [User!]!
  }

  type User {
    id: ID!
    username: String
  }

  input UserWhere @oneOf {
    foo: Int
    bar: Int
  }
`)

const resolvers = {
  Query: {
    users: () => [{ id: '1', username: '@mac' }],
  },
}

const server = new ApolloServer({
  schema: buildSubgraphSchema({ typeDefs, resolvers }), // federated graphql server, instead of `typeDefs, resolvers`
})
startStandaloneServer(server).then(({ url }) => console.log(`open ${url}`))

/*
# should return UserWhere type with isOneOf true

{
  __type(name: "UserWhere") {
    name
    isOneOf
  }
}

# as well as sdl, which also has UserWhere type marked with @oneOf

{
  _service { sdl }
}
*/

supergraph.mjs

import { ApolloServer } from '@apollo/server'
import { ApolloGateway, IntrospectAndCompose } from '@apollo/gateway'
import { startStandaloneServer } from '@apollo/server/standalone'

const gateway = new ApolloGateway({
  supergraphSdl: new IntrospectAndCompose({
    subgraphs: [{ name: 'demo', url: 'http://localhost:4000' }],
  }),
})

const server = new ApolloServer({ gateway })
startStandaloneServer(server, { listen: { port: 3000 } }).then(({ url }) => console.log(`open ${url}`))

/*
# Cannot query field "isOneOf" on type "__Type" 🤷‍♂️

{
  __type(name: "UserWhere") {
    name
    isOneOf
  }
}
*/