app.version is not stored at first use

[alexstrat]

I tried adding redux-persist-migrate to my stack.
Since it was the first time I used the lib, the app key was never in the initial state. As a consequence, upon persist/REHYDRATE reducement in redux-persist's defaultStateReconciler, the app key of the inboundState (containing the version) is simply ditched out because of this line:

// if initialState does not have key, skip auto rehydration
if (!state.hasOwnProperty(key)) return

It is easy to workaround this, for instance by adding a dummy app reducer, but it was not obvious to find. Since, I guess, it is a problem encountered by any new comer, shouldn't the workaround be part of the doc?

[giordy]

Yes, just wasted 2 hours in fact because of this. I confirm this problem.
In my opinion this is a major show stopper.
I confirm that I added a dummy reducer to work it around.

[StevePotter]

@giordy any chance you can post your placeholder reducer for others to use? Mine (used Flow types):

type SchemaState = {
  version?: number
}
const initialState: SchemaState = {}
const schemaVersion = (state: SchemaState = initialState) => state
export default schemaVersion

and in root reducer:

const rootReducer = combineReducers({
  schema
})

Of course, my 'app version' is 'schema'.

A good fix would be a custom state reconciler, or simply to require this extra reducer in the readme.

[giordy]

@StevePotter this is essentially what I did.

const REDUCERS = {
    reducer1,
    reducer2,
    ... // other reducers
};

// apply the fake reducer that maps migrations
REDUCERS[REDUCER_KEY] = (state={}) => state;

export default combineReducers(REDUCERS);

where REDUCER_KEY is the identifier used to map the state version ('app' in the example given in the README)

[pavoni]

Just followed the same path myself.

Would be great if someone could merge the fix from @IanVS.