[3.0.0] Regression with fragments that have fields with variables

[xzyfer]

We've run into an issue with fragments that have fields with variables.
This can come about when bubbling up fragments that are co-located with their component code.

Note: this is not to be mistaken with the experiment fragment variables feature.

I've done some debugging and narrowed the issue down tomergeSchemas.
Without it everything works as expected. I suspect something isn't get merged correctly.

Setup

Minimal reproduction setup

const gql = require('graphql-tag');
const makeExecutableSchema = require('graphql-tools').makeExecutableSchema;
const mergeSchemas = require('graphql-tools').mergeSchemas;
const SchemaLink = require('apollo-link-schema').SchemaLink;
const ApolloClient = require('apollo-client').ApolloClient;
const InMemoryCache = require('apollo-cache-inmemory').InMemoryCache;

const schema = makeExecutableSchema({
  typeDefs: `
    type Query {
      foo: Foo!
    }

    type Foo {
      name: String!
      bar(id: String!): Bar!
    }

    type Bar {
      name: String!
    }

    schema {
      query: Query
    }
  `,
  resolvers: {
    Query: {
      foo: () => ({ name: 'foo' }),
    },
    Foo: {
      bar: () => ({ name: 'bar' }),
    },
  },
});

const client = new ApolloClient({
  cache: new InMemoryCache(),
  link: new SchemaLink({
    schema: mergeSchemas({ schemas: [schema] }),
  }),
});

Execution

client.query({
  query: gql`
    query foo($id: String!) {
      foo(id: $id) {
        name
        ...BarFragment
      }
    }
    fragment BarFragment on Foo {
      bar(id: $id) {
        name
      }
    }
  `,
  variables: { id: 10 },
})
  .then(console.log)
  .catch(console.error);

Output in 2.x

> { data: { foo: { name: 'foo', bar: [Object], __typename: 'Foo' } },
  loading: false,
  networkStatus: 7,
  stale: false }

Output in 3.0.0-beta.0

> { Error: GraphQL error: Variable "$id" is not defined.
    at new ApolloError (/app/node_modules/apollo-client/bundle.umd.js:121:28)
    at /app/node_modules/apollo-client/bundle.umd.js:1187:41
    at /app/node_modules/apollo-client/bundle.umd.js:1620:17
    at Array.forEach (<anonymous>)
    at /app/node_modules/apollo-client/bundle.umd.js:1619:18
    at Map.forEach (<anonymous>)
    at QueryManager.broadcastQueries (/app/node_modules/apollo-client/bundle.umd.js:1614:22)
    at Object.next (/app/node_modules/apollo-client/bundle.umd.js:1660:31)
    at notifySubscription (/app/node_modules/zen-observable-ts/node_modules/zen-observable/lib/Observable.js:126:18)
    at onNotify (/app/node_modules/zen-observable-ts/node_modules/zen-observable/lib/Observable.js:161:3)
  graphQLErrors:
   [ { Error: Variable "$id" is not defined.
    at asErrorInstance (/app/node_modules/graphql/execution/execute.js:541:43)
    at <anonymous>
    at runMicrotasksCallback (internal/process/next_tick.js:121:5)
    at _combinedTickCallback (internal/process/next_tick.js:131:7)
    at process._tickDomainCallback (internal/process/next_tick.js:218:9)
       message: 'Variable "$id" is not defined.',
       locations: [],
       path: [Array] } ],
  networkError: null,
  message: 'GraphQL error: Variable "$id" is not defined.',
  extraInfo: undefined }

[freiksenet]

Sigh I've just moved those around to fix another bug.

Here is the problem: https://github.com/apollographql/graphql-tools/blob/master/src/transforms/FilterToSchema.ts#L100-L105

Fragments do usedVariables after operations.I guess a second pass on operations is needed to fix that.

[xzyfer]

I've bisected the regression to 663c9af

[hwillson]

#806 was merged (thanks @xzyfer!), and released in graphql-tools 3.0.3. Thanks all!