Revert PR #6353 and support options.nextFetchPolicy instead.

[benjamn]

PR #6353 seemed like a clever zero-configuration way to improve the default behavior of the cache-and-network and network-only fetch policies. Even though the word "network" is right there in the policy strings, it can be surprising (see #6305) to see network requests happening when you didn't expect them.

However, the wisdom of #6353 was contingent on this new behavior of falling back to cache-first not creating problems for anyone, and unfortunately that hope appears to have been overly optimistic/naive: #6677 (comment)

To keep everyone happy, I think we need to revert #6353 while providing an easy way to achieve the same effect, when that's what you want. The new options.nextFetchPolicy option allows updating options.fetchPolicy after the initial network request, without having to call observableQuery.setOptions. Specifically, passing { nextFetchPolicy: "cache-first" } for network-only or cache-and-network queries should restore the behavior of #6353.

This could be considered a breaking change, but it's also a regression from Apollo Client 2.x that needs fixing. We are confident options.nextFetchPolicy will enable the #6353 functionality where desired, and we are much more comfortable requiring the explicit use of options.nextFetchPolicy going forward.

[hwillson]

Looks great @benjamn! Adding nextFetchPolicy to https://github.com/apollographql/apollo-client/blob/master/docs/shared/query-options.mdx would be helpful as well. Thanks!

[pleunv]

Would it make sense to support nextFetchPolicy in the defaultOptions as well in order to easily get the old cache-and-network behavior back?

[sanketjo96]

@benjamn Is there any other way to get the old cache-and-network behavior by setting global option ?

[benjamn]

@sanketjo96 @pleunv There are some details to iron out (like #6839), but here's my basic plan for that: #6833 (comment)

[benjamn]

@pleunv @sanketjo96 With @apollo/client@3.2.0-beta.5 (which includes #6893), it should be possible to configure nextFetchPolicy globally, using a function instead of just a string:

new ApolloClient({
  link,
  cache,
  defaultOptions: {
    watchQuery: {
      nextFetchPolicy(lastFetchPolicy) {
        if (lastFetchPolicy === "cache-and-network" ||
            lastFetchPolicy === "network-only") {
          return "cache-first";
        }
        return lastFetchPolicy;
      },
    },
  },
})

It's important to use a function here, so you're only modifying cache-and-network and network-only, not any other fetch policies. It would be weird/wrong to change cache-only to cache-first, for example.

Hope that helps!

[pleunv]

@benjamn Awesome! Definitely does!

[aquelehugo]

@pleunv @sanketjo96 With @apollo/client@3.2.0-beta.5 (which includes #6893), it should be possible to configure nextFetchPolicy globally, using a function instead of just a string:

new ApolloClient({
  link,
  cache,
  defaultOptions: {
    watchQuery: {
      nextFetchPolicy(lastFetchPolicy) {
        if (lastFetchPolicy === "cache-and-network" ||
            lastFetchPolicy === "network-only") {
          return "cache-first";
        }
        return lastFetchPolicy;
      },
    },
  },
})

It's important to use a function here, so you're only modifying cache-and-network and network-only, not any other fetch policies. It would be weird/wrong to change cache-only to cache-first, for example.

Hope that helps!

@benjamn
I am trying to use it for defaultOptions.query and it is not available, defaultOptions.watchQuery seems to enable it anyway. Using version 3.2.7. Is it intended?