Since 2.6.0, FetchPolicy and react-apollo types that depend on it are broken

[adrienharnay]

Intended outcome:
<Query fetchPolicy="cache-and-network" /> should be valid.

Actual outcome:

This change: cf069bc#diff-88b34d7add139a9c0e7d4c2b1944a8dc

broke all external types that depend on FetchPolicy, e.g.

export interface QueryOpts<TGraphQLVariables = OperationVariables> {
    ssr?: boolean;
    variables?: TGraphQLVariables;
    fetchPolicy?: FetchPolicy;
    ...

used by the Query class.

How to reproduce the issue:
Update apollo-client and write <Query fetchPolicy="cache-and-network" /> in a typescript project.

Versions

System:
    OS: macOS 10.14.4
  Binaries:
    Node: 10.15.3 - /usr/local/bin/node
    Yarn: 1.16.0 - ~/Documents/GitHub/brigad/front-end/node_modules/.bin/yarn
    npm: 6.4.1 - /usr/local/bin/npm
  Browsers:
    Chrome: 74.0.3729.157
    Firefox: 65.0
    Safari: 12.1
  npmPackages:
    apollo: 2.12.2 => 2.12.2 

[alamothe]

Same issue. Does this mean cache-and-network is broken in 2.6.0?

[adrienharnay]

It does work, only the types are mistaken 🙂

[benjamn]

Thanks for reporting this issue, as we certainly did not intend this change to be so surprising. That said, this type change is meaningful, and adjusting your code to accommodate the new types (if necessary) is a good idea.

I've just released [email protected] which correctly uses WatchQueryFetchPolicy, and added a note to CHANGELOG.md about this change.

Please feel free to reopen this issue (or open a new issue) if the problem persists after updating to react-apollo@latest.

[benjamn]

Here's the note from CHANGELOG.md:

• The FetchPolicy type has been split into two types, so that passing cache-and-network to ApolloClient#query is now forbidden at the type level, whereas previously it was forbidden by a runtime invariant assertion:

  export type FetchPolicy =
    | 'cache-first'
    | 'network-only'
    | 'cache-only'
    | 'no-cache'
    | 'standby';
  
  export type WatchQueryFetchPolicy =
    | FetchPolicy
    | 'cache-and-network';

  The exception thrown if you ignore the type error has also been improved to explain the motivation behind this restriction.
  
  Issue #3130 (comment) and commit cf069bc7

[adrienharnay]

Thanks that is perfect! Just wanted to make sure no other third parties I'm not aware of (react-apollo or others) made use of this as well 🙂

Have a great day!

[alamothe]

Should we then file an issue against react-apollo?

The issue is that Query component does not allow to pass cache-and-network anymore. Basically, the change in type here broke react-apollo (it needs to switch to WatchQueryFetchPolicy at appropriate places).

[adrienharnay]

@alamothe a new version of react-apollo has been released, you should be able to update and the problem will be gone