Compare values before and after updating redux state

Question

I am listening to a Firebase node.....then when a change occurs in FBS Im comparing the snapshot versus what's currently in Redux. Crazy thing is that Redux state already reflects the updated value in FBS (from snapshot) even before I've dispatched

const listenToFbsMyUserNode = (dispatch) => {
  database()
    .ref('profiles/users/')
    .on('value', snapshot => {
      let state = store.getState(); //at this point Redux somehow already knows about the updated value before Ive dispatched!!!
      //now can dispatch
      dispatch(_refreshMyProfile(snapshot.val()));
    });
};

score 1 · Accepted Answer · answered May 21 '21 at 08:12

1

That means that you are probably copying Firebase objects into your store. Since Firebase does not work immutably, Firebase does modify these objects - essentially also modifying your store with a dispatch, since your store now contains references to exactly these objects. Something like that should of course not happen - convert your objects into flat data before dispatching them instead of dispatching the Firebase objects directly.

answered May 21 '21 at 08:12

phry

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Thanks for the answer.....totally correct, I am passing snapshot returned from FBS directly into store....extemely interesting it works that way. When you say "convert your objects into flat data"....you mean JSON.stringify()? – james murphy May 22 '21 at 03:26
There seems to be a `snapshot.data()` method for that: https://googleapis.dev/nodejs/firestore/latest/DocumentSnapshot.html#data – phry May 22 '21 at 09:21

Compare values before and after updating redux state

1 Answers1