Fix mutate

[promer94]

cache cant update
https://codesandbox.io/s/swr-mutate-bug-eujb4?file=/src/index.tsx

inflight request should be ignored
https://codesandbox.io/s/swr-mutate-bug2-39199?file=/src/index.tsx

mutate should update data
https://codesandbox.io/s/useswr-async-mutate-bug-y77z1?file=/src/App.js

close #1070; close #1074;

[codesandbox-ci]

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 536e25e:

Sandbox	Source
SWR-Basic	Configuration
SWR-States	Configuration
SWR-Infinite	Configuration
SWR-SSR	Configuration
swr mutate bug	PR
swr mutate bug2	PR
useSWR async mutate bug	PR
useSWR async mutate bug	Issue #1070
swr mutate bug	Issue #1074

[jameslouiz]

For "cache cant update", this works: https://codesandbox.io/s/swr-mutate-bug-forked-95od2?file=/src/index.tsx. Simply conditionally return a fetcher.

[promer94]

For "cache cant update", this works: https://codesandbox.io/s/swr-mutate-bug-forked-95od2?file=/src/index.tsx. Simply conditionally return a fetcher.

if you check the console.log, you will find fetcher never called.
SWR actually never updates the fetcher if the key stay same. In this example, fetcher in SWR is always null

[shuding]

Thank you!

[jameslouiz]

For "cache cant update", this works: https://codesandbox.io/s/swr-mutate-bug-forked-95od2?file=/src/index.tsx. Simply conditionally return a fetcher.

if you check the console.log, you will find fetcher never called.
SWR actually never updates the fetcher if the key stay same. In this example, fetcher in SWR is always null

Ah, yes. You're totally right.

This fix would help with a similar issue I have

[jameslouiz]

I managed to get it working by using isPaused: https://codesandbox.io/s/swr-mutate-bug-forked-95od2?file=/src/index.tsx