在 Kotlin 中将字符串（在数据类中）解码为日期

Question

How would i decode a string, contained in a data class, as a date. I have several strings, which are actually dates ("2022-11-24T23:37:34.668Z") . These are stored within documents in firebase (obviously there are not only date strings in the documents, but also other types). I want to deserialize so that the strings, which represent dates, are autmatically parsed as such.

Currently i decode like so:

private inline fun <reified T> parse(snapshot: DocumentSnapshot?): T? {
     return snapshot?.toObject<T>(T::class.java)
}

I do not see a way how to specify a date decoder. Therefore, how do i achieve this.

Answer 1

There is indeed no way to specify a custom decoder for a specific field/property.

The best options I can quickly think of are:

• Add custom functions to the data class to parse the string to a date, and to set a new value as a date and marking them as excluded from the database.
• Define a custom class for the string field (eg StringDate ), which handles the same parsing and serializing and then use that in your data class.

I don't know of existing public implementations of either of these.

Of course the easiest option would be to store the date/time value in a Timestamp field that the Firestore SDK then automatically convert to the native date/time type on each supported platform.