ApolloClient: ObservableQuery.map/.filter/.reduce/.flatMap don't work

Intended outcome: I’d like to use the basic zen-observable methods like map and filter to pipe the results of a query through some transformations before subscribing to it.

apolloClient.watchQuery({ query })
  .map(result => transformResult(result))
  .subscribe(console.log);

The docs say “Refer to the zen-observable documentation for additional context and API options.” — I read that as the standard zen-observable API should be available and cooperate with the ObservableQuery API.

Actual outcome:

Calling any of the above methods cause runtime errors that look like:

/sandbox/node_modules/apollo-client/bundle.umd.js:146
      _this.variables = options.variables || {};
                                ^

TypeError: Cannot read property 'variables' of undefined

The actual line of code where the error occurs is here.

How to reproduce the issue:

Reproduction: https://codesandbox.io/embed/apollo-client-observable-query-map-509cw

zen-observable seems to support subclassing, but it assumes that the subclass constructor has the same signature. This creates two problems:

1. When .map creates a new ObservableQuery, it doesn’t know about the constructor’s queryManager, options, and shouldSubscribe arguments.
2. Even after I hacked in support for new ObservableQuery(fn), the new observable returned from .map doesn’t have a query manager so ObservableQuery’s methods like refetch do not work.

Versions

apollo-client@2.6.4

[jhampton]

@hwillson Do we have a sense if this might be address in AC3?

[oscar6echo]

What works for me:

import Observable from 'zen-observable';
// client built from from 'apollo-client' not 'apollo-boost';

const obs = client.subscribe({
    query: gql(queryString),
    variables,
    ...opts
  });
  const obs2 = Observable.from(obs).map((e) => transform(e));
  obs2.subscribe({
    next,
    error,
    complete
  });