Hook for triggering validations manually (passive mode) by shuding · Pull Request #1262 · vercel/swr

shuding · 2021-07-02T00:22:46Z

Motivation

There are a lot of existing discussions and feature requests about doing requests manually in SWR (e.g. #93, #116, #550, #1082), and we do see some valid use cases for it. In short, we need something that:

Do not revalidate automatically (mount, focus, reconnect, retry...)
Return a callback function for triggering the validation manually
Backfill the request response to the cache*

*: Potentially we can have a switch to turn on/off this step.

One option is to have a new hook, because the arguments would be slightly different from the useSWR hook. Since we now have better abstractions to build such a hook, namely middlewares and revalidateWhenStale, this PR is such an attempt.

`useSWRTrigger`

import useSWRTrigger from 'swr/trigger'

// fetcher impl.
function getData(url, token, opts) { ... }

// normal SWR API, but it will never start the request
const { data, error, mutate, trigger } = useSWRTrigger('/api/user', getData, { onError, onSuccess })

// trigger it manually, args will be passed to the fetcher (after the key arg/args)
trigger('myToken', myOptions)

// wait until it's done
await trigger('myToken', myOptions)

The trigger() call will still reflect the hook-returned data and error with a re-render, but that's more declarative.

To-dos

Finalize the name of the hook.
Sometimes, mutation APIs (POST, PUT, DELETE) return different payload from the GET API. It might be an issue if we write back to the cache with the same key. This behavior needs to be reconsidered.
If the mutation APIs' results cannot be cached, that normally means that we need to revalidate those keys again if there's a useSWR hook with the same key. This can be another option to consider.
Ensure callbacks and isValidating state are working as expected.
Ensure with a test case that under trigger mode there's no deduping.
Ensure with a test case that trigger prevents race conditions with normal GET requests.
(docs) Have a specific list of options, that can be used in useSWRTrigger and ignore the others.

codesandbox-ci · 2021-07-02T00:23:33Z

This pull request is automatically built and testable in CodeSandbox.

To see build info of the built libraries, click here or the icon next to each commit SHA.

Latest deployment of this branch, based on commit be647cc:

Sandbox	Source
SWR-Basic	Configuration
SWR-States	Configuration
SWR-Infinite	Configuration
SWR-SSR	Configuration

giuseppeg · 2021-08-10T20:02:06Z

trigger/index.ts

+      if (!fetcher) throw new Error('Missing SWR fetcher.')
+
+      // Mutate the SWR data and return the result.
+      return swr.mutate(


RE:

Sometimes, mutation APIs (POST, PUT, DELETE) return different payload from the GET API. It might be an issue if we write back to the cache with the same key. This behavior needs to be reconsidered.

When the user is not interested in updating the global cache for key they can use the fetcher right away i.e. they won't need useSWRTrigger right?

Yes. But I'm also thinking about an option to prevent updating the cache, but then useSWRTrigger will have nothing "SWR". Haven’t decided yet.

trigger/index.ts

shuding · 2021-08-19T12:47:10Z

This API needs more discussions, will keep it on hold for 1.0.

shuding · 2021-09-08T14:58:29Z

Some thoughts:

Passive hooks still need to have a key specified, even if it's not used by that request. Remote mutations are associated with normal GET requests, we need the key to avoid race conditions and do cache write back.
Each passive hook needs to have its own states (data, error, isValidating), which won't be shared with useSWR or other passive hooks with the same key.
Error retry should be turned off by default as remote mutations will be more likely to get 4xx errors than GET requests, and retrying won't help.
There should be a way to reset/clear the state as the request can be triggered again, and it is not idempotent like GET requests.
There should be an option to enable/disable writing back the value into the cache, as well as triggering a revalidation after it ends.

giuseppeg · 2021-09-08T15:21:08Z

Some thoughts:

Passive hooks still need to have a key specified, even if it's not used by that request. Remote mutations are associated with normal GET requests, we need the key to avoid race conditions and do cache write back.

Each passive hook needs to have its own states (data, error, isValidating), which won't be shared with useSWR or other passive hooks with the same key.

The solution that I am currently using (https://twitter.com/giuseppegurgone/status/1427576808204034061) is close to this except that I don't use a key and revalidate but mutate programmatically.

I think that triggering a revalidation (a GET request) when the remote mutation is complete is a good option although it could be redundant work, lead to higher consumption of resources since the mutation could already return the fresh data.

shuding · 2021-09-12T15:05:01Z

Continuing this feature in #1450.

add passive middleware

9000a7b

shuding added 6 commits July 2, 2021 13:41

merge master

3260d8c

update package.json

b075dbf

merge master

f4aaf0a

type fixes

9fd93db

add test

aac7c94

throw error when not able to fetch

56aee3c

shuding added this to the 1.0 milestone Jul 19, 2021

shuding added 2 commits July 20, 2021 13:52

Merge branch 'master' into passive

d7c743d

rename to trigger

41bb38e

shuding changed the title ~~Add passive middleware~~ Hook for triggering validations manually (passive mode) Aug 8, 2021

shuding added 5 commits August 9, 2021 23:00

fix comment

5983d86

Merge branch 'master' into passive

7ace8b2

disable global fetcher

b3e8adb

add more tests

fab3982

handle success and error callbacks; fix type errors

6e52d1b

giuseppeg reviewed Aug 10, 2021

View reviewed changes

shuding added 9 commits August 12, 2021 13:55

add test case for onError

8522a94

fix isValidating; simplify impl.

8f2a0d4

add test about deduping

4a8a62a

refactor revalidators

48e5f2a

decouple revalidators and state updaters

ac2757b

add trigger option

0467997

Merge branch 'master' into passive

8b712fd

fix: add trigger symbol

d9c6f1e

add test of race condition

be647cc

huozhi modified the milestones: 1.0, backlog Aug 17, 2021

shuding added the on hold label Aug 19, 2021

huozhi modified the milestones: backlog, 1.1 Aug 28, 2021

shuding mentioned this pull request Sep 3, 2021

mutate() and the deduping interval #1417

Open

shuding mentioned this pull request Sep 12, 2021

feat: Hook for remote mutations #1450

Merged

12 tasks

shuding closed this Sep 12, 2021

shuding deleted the passive branch September 12, 2021 15:03

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Hook for triggering validations manually (passive mode)#1262

Hook for triggering validations manually (passive mode)#1262
shuding wants to merge 23 commits intomasterfrom
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