Apollo-server: 2.x - Aliases do not work with default resolvers in merged schemas

Created on 25 Sep 2018  Â·  12Comments  Â·  Source: apollographql/apollo-server

I opened an issue on graphql-js: https://github.com/graphql/graphql-js/issues/1530#event-1862105684

Comment by Dan https://github.com/apollographql/apollo-server/issues/1724#issuecomment-425596109

This issues doesn't seem to be related to fragments. Aliases do not appear to be working with default resolvers in merged schemas:

OP:

Basically, when using fragments in a hierarchy like the below query, aliases don't work and can return non-nullable errors or they simply just cause the objects to be null.

It appears that my issue may not be related to the parser itself. This is a bug that was introduced when I upgraded to Apollo Server 2.x. I even rolled back every package _except_ apollo-server to what I had before and the issue persists.

Playground: https://pinto-hip.glitch.me

Issue the query:

{
  books {
    name
    categoryHierarchy {
      ...category
      categories {
        ...category
      }
    }
  }
}

fragment category on Category {
  abc: name
}

Error:

{
  "data": {
    "books": [
      {
        "name": "Harry Potter and the Chamber of Secrets",
        "categoryHierarchy": [
          null
        ]
      },
      {
        "name": "Jurassic Park",
        "categoryHierarchy": [
          null
        ]
      }
    ]
  },
  "errors": [
    {
      "message": "Expected Iterable, but did not find one for field Category.categories.",
      "locations": [
        {
          "line": 6,
          "column": 7
        }
      ],
      "path": [
        "books",
        0,
        "categoryHierarchy",
        0,
        "categories"
      ],
      "extensions": {
        "code": "INTERNAL_SERVER_ERROR",
        "exception": {
          "stacktrace": [
            "Error: Expected Iterable, but did not find one for field Category.categories.",
            "    at invariant (/rbd/pnpm-volume/0897a123-e913-41b8-a689-0921f96aa33a/node_modules/.registry.npmjs.org/graphql/0.13.2/node_modules/graphql/jsutils/invariant.js:19:11)",
            "    at completeListValue (/rbd/pnpm-volume/0897a123-e913-41b8-a689-0921f96aa33a/node_modules/.registry.npmjs.org/graphql/0.13.2/node_modules/graphql/execution/execute.js:673:65)",
            "    at completeValue (/rbd/pnpm-volume/0897a123-e913-41b8-a689-0921f96aa33a/node_modules/.registry.npmjs.org/graphql/0.13.2/node_modules/graphql/execution/execute.js:643:12)",
            "    at completeValue (/rbd/pnpm-volume/0897a123-e913-41b8-a689-0921f96aa33a/node_modules/.registry.npmjs.org/graphql/0.13.2/node_modules/graphql/execution/execute.js:629:21)",
            "    at completeValueWithLocatedError (/rbd/pnpm-volume/0897a123-e913-41b8-a689-0921f96aa33a/node_modules/.registry.npmjs.org/graphql/0.13.2/node_modules/graphql/execution/execute.js:580:21)",
            "    at completeValueCatchingError (/rbd/pnpm-volume/0897a123-e913-41b8-a689-0921f96aa33a/node_modules/.registry.npmjs.org/graphql/0.13.2/node_modules/graphql/execution/execute.js:550:12)",
            "    at resolveField (/rbd/pnpm-volume/0897a123-e913-41b8-a689-0921f96aa33a/node_modules/.registry.npmjs.org/graphql/0.13.2/node_modules/graphql/execution/execute.js:497:10)",
            "    at /rbd/pnpm-volume/0897a123-e913-41b8-a689-0921f96aa33a/node_modules/.registry.npmjs.org/graphql/0.13.2/node_modules/graphql/execution/execute.js:364:18",
            "    at Array.reduce (<anonymous>)",
            "    at executeFields (/rbd/pnpm-volume/0897a123-e913-41b8-a689-0921f96aa33a/node_modules/.registry.npmjs.org/graphql/0.13.2/node_modules/graphql/execution/execute.js:361:42)"
          ]
        }
      }
    },
    {
      "message": "Expected Iterable, but did not find one for field Category.categories.",
      "locations": [
        {
          "line": 6,
          "column": 7
        }
      ],
      "path": [
        "books",
        1,
        "categoryHierarchy",
        0,
        "categories"
      ],
      "extensions": {
        "code": "INTERNAL_SERVER_ERROR",
        "exception": {
          "stacktrace": [
            "Error: Expected Iterable, but did not find one for field Category.categories.",
            "    at invariant (/rbd/pnpm-volume/0897a123-e913-41b8-a689-0921f96aa33a/node_modules/.registry.npmjs.org/graphql/0.13.2/node_modules/graphql/jsutils/invariant.js:19:11)",
            "    at completeListValue (/rbd/pnpm-volume/0897a123-e913-41b8-a689-0921f96aa33a/node_modules/.registry.npmjs.org/graphql/0.13.2/node_modules/graphql/execution/execute.js:673:65)",
            "    at completeValue (/rbd/pnpm-volume/0897a123-e913-41b8-a689-0921f96aa33a/node_modules/.registry.npmjs.org/graphql/0.13.2/node_modules/graphql/execution/execute.js:643:12)",
            "    at completeValue (/rbd/pnpm-volume/0897a123-e913-41b8-a689-0921f96aa33a/node_modules/.registry.npmjs.org/graphql/0.13.2/node_modules/graphql/execution/execute.js:629:21)",
            "    at completeValueWithLocatedError (/rbd/pnpm-volume/0897a123-e913-41b8-a689-0921f96aa33a/node_modules/.registry.npmjs.org/graphql/0.13.2/node_modules/graphql/execution/execute.js:580:21)",
            "    at completeValueCatchingError (/rbd/pnpm-volume/0897a123-e913-41b8-a689-0921f96aa33a/node_modules/.registry.npmjs.org/graphql/0.13.2/node_modules/graphql/execution/execute.js:550:12)",
            "    at resolveField (/rbd/pnpm-volume/0897a123-e913-41b8-a689-0921f96aa33a/node_modules/.registry.npmjs.org/graphql/0.13.2/node_modules/graphql/execution/execute.js:497:10)",
            "    at /rbd/pnpm-volume/0897a123-e913-41b8-a689-0921f96aa33a/node_modules/.registry.npmjs.org/graphql/0.13.2/node_modules/graphql/execution/execute.js:364:18",
            "    at Array.reduce (<anonymous>)",
            "    at executeFields (/rbd/pnpm-volume/0897a123-e913-41b8-a689-0921f96aa33a/node_modules/.registry.npmjs.org/graphql/0.13.2/node_modules/graphql/execution/execute.js:361:42)"
          ]
        }
      }
    }
  ]
}
bug has-reproduction
Source
picture kamranayub

All 12 comments

Do you have an example of some server code that reproduces this?

dncrews picture dncrews on 27 Sep 2018

In the glitch code linked?

On Thu, Sep 27, 2018, 15:40 Dan Crews notifications@github.com wrote:

Do you have an example of some server code that reproduces this?

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Reply to this email directly, view it on GitHub
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kamranayub picture kamranayub on 27 Sep 2018

sorry; didn't see a link to the source, and I didn't know glitch's url mechanism. Got it

dncrews picture dncrews on 27 Sep 2018

Expected Iterable, but did not find one for field Category.categories.

The error message is correct Your bug is here:

  const books = [
    {
      name: 'Harry Potter and the Chamber of Secrets',
      author: 'J.K. Rowling',
      categoryHierarchy: [
        { name: 'Fiction', categories: { name: 'Fantasy', categories: [] } }
      ]
    },
    {
      name: 'Jurassic Park',
      author: 'Michael Crichton',
      categoryHierarchy: [
        { name: 'Fiction', categories: { name: 'Sci-Fi', categories: [] } }
      ]
    },
  ];

You aren't returning an Iterable (array) for the first level of categories. Should be:

  const books = [
    {
      name: 'Harry Potter and the Chamber of Secrets',
      author: 'J.K. Rowling',
      categoryHierarchy: [
        { name: 'Fiction', categories: [ { name: 'Fantasy', categories: [] } ] }
      ]
    },
    {
      name: 'Jurassic Park',
      author: 'Michael Crichton',
      categoryHierarchy: [
        { name: 'Fiction', categories: [ { name: 'Sci-Fi', categories: [] } ] }
      ]
    },
  ];
dncrews picture dncrews on 27 Sep 2018
😄1

Dang it, I need to try to reproduce it since I'm definitely returning the same structure as I was in apollo-server 1.x in the resolvers, so give me some time to get a proper repro.

One thing I'm doing in my actual app is using mergeSchemas since we keep separate schemas. I'll try to build out the example to see if I can truly reproduce it.

kamranayub picture kamranayub on 28 Sep 2018

@dncrews OK, I've managed to reproduce it (check the Glitch again)--it definitely seems to be due to my usage of makeExecutableSchema and mergeSchemas. Is there something I'm doing wrong? I thought I was following the docs correctly: https://www.apollographql.com/docs/graphql-tools/schema-stitching.html#adding-resolvers

{
  books {
    books {
      name
      author
      categories {
        ...category
        sub_categories {
          ...category
          sub_categories {
            ...category
          }
        }
      }
    }
  }
}

fragment category on Category {
  id: category_id
  name
}

Response:

{
  "data": {
    "books": {
      "books": [
        {
          "name": "Harry Potter and the Chamber of Secrets",
          "author": "J.K. Rowling",
          "categories": [
            null
          ]
        },
        {
          "name": "Jurassic Park",
          "author": "Michael Crichton",
          "categories": [
            null
          ]
        }
      ]
    }
  },
  "errors": [
    {
      "message": "Cannot return null for non-nullable field Category.category_id.",
      "locations": [
        {
          "line": 20,
          "column": 3
        }
      ],
      "path": [
        "books",
        "books",
        0,
        "categories",
        0,
        "id"
      ],
      "extensions": {
        "code": "INTERNAL_SERVER_ERROR",
        "exception": {
          "stacktrace": [
            "Error: Cannot return null for non-nullable field Category.category_id.",
            "    at completeValue (/rbd/pnpm-volume/0897a123-e913-41b8-a689-0921f96aa33a/node_modules/.registry.npmjs.org/graphql/0.13.2/node_modules/graphql/execution/execute.js:631:13)",
            "    at completeValueWithLocatedError (/rbd/pnpm-volume/0897a123-e913-41b8-a689-0921f96aa33a/node_modules/.registry.npmjs.org/graphql/0.13.2/node_modules/graphql/execution/execute.js:580:21)",
            "    at completeValueCatchingError (/rbd/pnpm-volume/0897a123-e913-41b8-a689-0921f96aa33a/node_modules/.registry.npmjs.org/graphql/0.13.2/node_modules/graphql/execution/execute.js:550:12)",
            "    at resolveField (/rbd/pnpm-volume/0897a123-e913-41b8-a689-0921f96aa33a/node_modules/.registry.npmjs.org/graphql/0.13.2/node_modules/graphql/execution/execute.js:497:10)",
            "    at /rbd/pnpm-volume/0897a123-e913-41b8-a689-0921f96aa33a/node_modules/.registry.npmjs.org/graphql/0.13.2/node_modules/graphql/execution/execute.js:364:18",
            "    at Array.reduce (<anonymous>)",
            "    at executeFields (/rbd/pnpm-volume/0897a123-e913-41b8-a689-0921f96aa33a/node_modules/.registry.npmjs.org/graphql/0.13.2/node_modules/graphql/execution/execute.js:361:42)",
            "    at collectAndExecuteSubfields (/rbd/pnpm-volume/0897a123-e913-41b8-a689-0921f96aa33a/node_modules/.registry.npmjs.org/graphql/0.13.2/node_modules/graphql/execution/execute.js:772:10)",
            "    at completeObjectValue (/rbd/pnpm-volume/0897a123-e913-41b8-a689-0921f96aa33a/node_modules/.registry.npmjs.org/graphql/0.13.2/node_modules/graphql/execution/execute.js:762:10)",
            "    at completeValue (/rbd/pnpm-volume/0897a123-e913-41b8-a689-0921f96aa33a/node_modules/.registry.npmjs.org/graphql/0.13.2/node_modules/graphql/execution/execute.js:660:12)"
          ]
        }
      }
    },
    {
      "message": "Cannot return null for non-nullable field Category.category_id.",
      "locations": [
        {
          "line": 20,
          "column": 3
        }
      ],
      "path": [
        "books",
        "books",
        1,
        "categories",
        0,
        "id"
      ],
      "extensions": {
        "code": "INTERNAL_SERVER_ERROR",
        "exception": {
          "stacktrace": [
            "Error: Cannot return null for non-nullable field Category.category_id.",
            "    at completeValue (/rbd/pnpm-volume/0897a123-e913-41b8-a689-0921f96aa33a/node_modules/.registry.npmjs.org/graphql/0.13.2/node_modules/graphql/execution/execute.js:631:13)",
            "    at completeValueWithLocatedError (/rbd/pnpm-volume/0897a123-e913-41b8-a689-0921f96aa33a/node_modules/.registry.npmjs.org/graphql/0.13.2/node_modules/graphql/execution/execute.js:580:21)",
            "    at completeValueCatchingError (/rbd/pnpm-volume/0897a123-e913-41b8-a689-0921f96aa33a/node_modules/.registry.npmjs.org/graphql/0.13.2/node_modules/graphql/execution/execute.js:550:12)",
            "    at resolveField (/rbd/pnpm-volume/0897a123-e913-41b8-a689-0921f96aa33a/node_modules/.registry.npmjs.org/graphql/0.13.2/node_modules/graphql/execution/execute.js:497:10)",
            "    at /rbd/pnpm-volume/0897a123-e913-41b8-a689-0921f96aa33a/node_modules/.registry.npmjs.org/graphql/0.13.2/node_modules/graphql/execution/execute.js:364:18",
            "    at Array.reduce (<anonymous>)",
            "    at executeFields (/rbd/pnpm-volume/0897a123-e913-41b8-a689-0921f96aa33a/node_modules/.registry.npmjs.org/graphql/0.13.2/node_modules/graphql/execution/execute.js:361:42)",
            "    at collectAndExecuteSubfields (/rbd/pnpm-volume/0897a123-e913-41b8-a689-0921f96aa33a/node_modules/.registry.npmjs.org/graphql/0.13.2/node_modules/graphql/execution/execute.js:772:10)",
            "    at completeObjectValue (/rbd/pnpm-volume/0897a123-e913-41b8-a689-0921f96aa33a/node_modules/.registry.npmjs.org/graphql/0.13.2/node_modules/graphql/execution/execute.js:762:10)",
            "    at completeValue (/rbd/pnpm-volume/0897a123-e913-41b8-a689-0921f96aa33a/node_modules/.registry.npmjs.org/graphql/0.13.2/node_modules/graphql/execution/execute.js:660:12)"
          ]
        }
      }
    }
  ]
}
kamranayub picture kamranayub on 28 Sep 2018

This issues doesn't seem to be related to fragments. Aliases do not appear to be working with default resolvers in merged schemas:

This doesn't work:

  const typeDefs = gql`
    type Query {
      book: Book
    }

    type Book {
      category: String!
    }
  `;

  const schema = makeExecutableSchema({ typeDefs });

  const resolvers = {
    Query: {
      book: () => ({ category: 'Test' })
    }
  };

  const server = new ApolloServer({
    schema: mergeSchemas({
      schemas: [ schema ],
      resolvers
    }),
  });

This does:

  const typeDefs = gql`
    type Query {
      book: Book
    }

    type Book {
      category: String!
    }
  `;

  const schema = makeExecutableSchema({ typeDefs });

  const resolvers = {
    Query: {
      book: () => ({ category: 'Test' })
    },
    Book: {
      category: (parent) => parent.category // Adding default resolver to fix bug
    }
  };

  const server = new ApolloServer({
    schema: mergeSchemas({
      schemas: [ schema ],
      resolvers
    }),
  });
dncrews picture dncrews on 29 Sep 2018
😕1

For now working around using:

import { keyBy, mapValues } from "lodash";

const monkeyPatchForAliases = (...props) =>
  mapValues(
    keyBy(props.map(prop => ({ prop, fn: parent => parent[prop] })), "prop"),
    obj => obj.fn
  );

const resolvers = {
    Query: {
      book: () => ({ category: 'Test' })
    },
    Book: monkeyPatchForAliases("category")
  };

😢

Would be great to get this prioritized, it's definitely a breaking bug and would prevent large projects from migrating.

kamranayub picture kamranayub on 4 Oct 2018

@kamranayub Are you sure you're using the latest version of apollo-server? I tried to reproduce the issue and it seems to work just fine. Running with node v8.11.3 and this code: gist

souserge picture souserge on 4 Oct 2018

I can double check, have you run the glitch code? That is reproducing the
issue live as Dan found.

On Thu, Oct 4, 2018, 12:15 Serge Korzh notifications@github.com wrote:

@kamranayub https://github.com/kamranayub Are you sure you're using the
latest version of apollo-server? I tried to reproduce the issue and it
seems to work just fine. Running with node v8.11.3 and this code: gist
https://gist.github.com/souserge/427d8ef5f9d7f48f120bc52d56917c29

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You are receiving this because you were mentioned.
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kamranayub picture kamranayub on 4 Oct 2018

@souserge With your code and deps it still fails. See:

# Write your query or mutation here
{
  book {
    cat: category
  }
}

And the code: https://glitch.com/edit/#!/pinto-hip

kamranayub picture kamranayub on 5 Oct 2018

Closing for now, opened in graphql-tools repo.

kamranayub picture kamranayub on 5 Oct 2018
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