Manipulate Value Stored In Firebase Document Field Before Applying Order By

In my Firebase Firestore, I have a large number of documents in a collection, each of which has a field called bookTime, which stores a date in String format. The format is dd MM y

Solution 1:

What change should I make so I can actually get a list with the document having newest bookTime on top?

First of all, don't use Strings to store dates. It's recommended to use Date objects. The Date is a Firestore supported data type.

For more information on how to store a Date, please see my answer from the following post:

• ServerTimestamp is always null on Firebase Firestore

Once you store the Date correctly, that query will work perfectly fine.

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However, if you insist to store the dates and times as Strings, the option that you have is to store them in a format that can be sorted lexicographical and chronological at the same time.

The ISO 8601 format looks like this:

20200329T184525

That's the current time I'm answering this question.

March29,2020 6:45:25 PMUTC