Safe migration from AsyncStorage to redux-persist-filesystem-storage

[maxkomarychev]

Hello,

update I'm on redux-persist v4
update 2 works for redux-persist v4 ONLY

I am writing custom migration routine that will take data that was saved with one storage and save it under another one. More specifically I want to migrate from AsyncStorage to https://github.com/robwalkerco/redux-persist-filesystem-storage to prevent issues related to sqlite size/cursor memory limits on android. Please find snippet below, do you think it is the best way to do such thing? Is there any better way to tell if store was previously saved than checking _.isEmpty(state)?

update added try-catch

const fsPersistor = persistStore(
    this.store,
    { storage: FilesystemStorage },
    (fsError, fsResult) => {
        if (_.isEmpty(fsResult)) {
            try {
                getStoredState(
                    { storage: AsyncStorage },
                    (asyncError, asyncResult) => {
                        if (!_.isEmpty(asyncResult)) {
                            fsPersistor.rehydrate(asyncResult, {
                                serial: false,
                            })
                        }
                    },
                )
            } catch (getStateError) {
                console.warn('getStoredState error', getStateError)
            }
        }
    },
)

update 2 with promises

const fsPersistor = persistStore(
    this.store,
    { storage: FilesystemStorage },
    async (fsError, fsResult) => {
        if (_.isEmpty(fsResult)) {
            try {
                const asyncState = await getStoredState({
                    storage: AsyncStorage,
                })
                if (!_.isEmpty(asyncState)) {
                    fsPersistor.rehydrate(asyncState, {
                        serial: false,
                    })
                }
            } catch (getStateError) {
                console.warn('getStoredState error', getStateError)
            }
        }
    },
)

Thanks.

[maxkomarychev]

another version with promises (1st message updated)

const fsPersistor = persistStore(
    this.store,
    { storage: FilesystemStorage },
    async (fsError, fsResult) => {
        if (_.isEmpty(fsResult)) {
            try {
                const asyncState = await getStoredState({
                    storage: AsyncStorage,
                })
                if (!_.isEmpty(asyncState)) {
                    fsPersistor.rehydrate(asyncState, {
                        serial: false,
                    })
                }
            } catch (getStateError) {
                console.warn('getStoredState error', getStateError)
            }
        }
    },
)

[rt2zz]

this looks great / correct! Unfortunately this approach only works for v4, but very similar code can be adapted for a v4 -> v5 upgrade.

Basically in v5 the approach is to have a custom config.getStoredState that does a fallback check for v4: https://github.com/rt2zz/redux-persist/blob/master/docs/MigrationGuide-v5.md#experimental-v4-to-v5-state-migration

Open to suggestion on how to make these types of migrations more painless. I am contemplating something like createGetStoredStateChain([getStoredStateA, getStoredStateFallback]) which basically will go down the chain until it finds usable stored state.

[maxkomarychev]

this looks great / correct! Unfortunately this approach only works for v4

that is true, I updated 1st post

[alanlanglois]

I'm a little confuse, any place where I can find an example of AsyncStorage to redux-persist-filesystem-storage migration using V5?

[alanlanglois]

Working on it
I can get previously stored data using AsyncStorage:

let persistor = persistStore(store, persistConfig, async () => {
      try {
          console.log("Get Async State")
          const asyncState = await getStoredState({
              key: 'root',
              storage: AsyncStorage,
          })

          console.log("Async State: " + asyncState )
          if (asyncState) {
              console.log("Stored Async Data" + JSON.stringify(asyncState));
          }
      } catch (error) {
          console.warn('Get Async State error', error)
      }

but I can't really see how rehydrate the file storage store with these data, as fsPersistor.rehydrate doesn't exists anymore in v5.

Should I use Transform? or is there a method replacing .rehydrate in v5?

[hutchy2570]

See #806 (comment)