Minor Changes

New Fetcher APIs

Per this RFC, we've introduced some new APIs that give you more granular control over your fetcher behaviors. (#10960)

• You may now specify your own fetcher identifier via useFetcher({ key: string }), which allows you to access the same fetcher instance from different components in your application without prop-drilling
• Fetcher keys are now exposed on the fetchers returned from useFetchers so that they can be looked up by key
• Form and useSumbit now support optional navigate/fetcherKey props/params to allow kicking off a fetcher submission under the hood with an optionally user-specified key
  • <Form method="post" navigate={false} fetcherKey="my-key">
  • submit(data, { method: "post", navigate: false, fetcherKey: "my-key" })
  • Invoking a fetcher in this way is ephemeral and stateless
  • If you need to access the state of one of these fetchers, you will need to leverage useFetchers() or useFetcher({ key }) to look it up elsewhere

Persistence Future Flag (future.v7_fetcherPersist)

Per the same RFC as above, we've introduced a new future.v7_fetcherPersist flag that allows you to opt-into the new fetcher persistence/cleanup behavior. Instead of being immediately cleaned up on unmount, fetchers will persist until they return to an idle state. This makes pending/optimistic UI much easier in scenarios where the originating fetcher needs to unmount. (#10962)

• This is sort of a long-standing bug fix as the useFetchers() API was always supposed to only reflect in-flight fetcher information for pending/optimistic UI -- it was not intended to reflect fetcher data or hang onto fetchers after they returned to an idle state
• Keep an eye out for the following specific behavioral changes when opting into this flag and check your app for compatibility:
  • Fetchers that complete while still mounted will no longer appear in useFetchers() after completion - they served no purpose in there since you can access the data via useFetcher().data
  • Fetchers that previously unmounted while in-flight will not be immediately aborted and will instead be cleaned up once they return to an idle state
    • They will remain exposed via useFetchers while in-flight so you can still access pending/optimistic data after unmount
    • If a fetcher is no longer mounted when it completes, then it's result will not be post processed - e.g., redirects will not be followed and errors will not bubble up in the UI
    • However, if a fetcher was re-mounted elsewhere in the tree using the same key, then it's result will be processed, even if the originating fetcher was unmounted

Other Minor Changes

• Add support for optional path segments in matchPath (#10768)

Patch Changes

• Fix the future prop on BrowserRouter, HashRouter and MemoryRouter so that it accepts a Partial<FutureConfig> instead of requiring all flags to be included (#10962)
• Fix router.getFetcher/router.deleteFetcher type definitions which incorrectly specified key as an optional parameter (#10960)

Full Changelog: 6.17.0...6.18.0