Method for coverting all Firestore Timestamps in a snapshot to JS dates?

Question

How would you write a method to convert all Firestore Timestamps in a snapshot to JavaScript Dates?

For example, a snapshot from a posts collection might return a couple Firestore Timestamps (createdDtTm, modifyDtTm):

[
  { 
    text: 'My new post', 
    uid: 'nzjNp3Q', 
    createDtTm: Timestamp { seconds: 1596239999, nanoseconds: 999000000 },
    modifyDtTm: Timestamp { seconds: 1596239999, nanoseconds: 999000000 },  
  }, 
  { 
    text: 'Another post', 
    uid: 'nzjNp3Q', 
    createDtTm: Timestamp { seconds: 1596239999, nanoseconds: 999000000 },
    modifyDtTm: Timestamp { seconds: 1596239999, nanoseconds: 999000000 },  
  }, 
]

Converting the individual dates is simple enough by mapping over the array and using the toDate() method for each Timestamp (e.g., createDtTm.toDate())

But what is a more generalized approach for converting these two (or any any arbitrary number of) Firestore timestamps, without explicitly specifying the Timestamp fields?

For instance, do Firestore Timestamps have a unique type that could be used for identification? Would an assumption of naming conventions be required (e.g., field name contains DtTm)? Other?

Previous questions answer how to convert a single Timestamp or a single timestamp in multiple documents in a snapshot. But I haven't found a generalized approach for converting all Timestamps within a snapshot when multiple Timestamps exist. More specifically, I'm interested in an approach for use within a React Provider that would pass JavaScript dates (not Firestore Timestamps) to its Consumers, while also not creating a dependency to update the Provider each time a new Timestamp field is added to the data model / collection.

score 2 · Accepted Answer · edited Aug 12 '20 at 11:33

I don't think there is any global method for this, but I think its easy to create a function that will analyze snapshot and change it. It's not very complicated. In node.js I have done it like this:

function globalToData (snapshot) {
      for (const field in snapshot)
  
    if (snapshot[field] instanceof Firestore.Timestamp) { 
        snapshot[field] = snapshot[field].toDate()
    }
    else if (snapshot[field] instanceof Object) { 
        globalToData (snapshot[field]);
    }
    return snapshot;
};

if you get DocumentSnapshot as ex. snap you can call it like:

globalToData(snap.data())

This should convert all Timestamps in all levels of Document snapshot ( I tested to 3rd level of nesting mixed map and array). We do not have your solution, but you can implement this somewhere in the middle of your app.

Method for coverting all Firestore Timestamps in a snapshot to JS dates?

1 Answers1