ServerTimestamp

@Retention(value = RetentionPolicy.RUNTIME)
@Target(value = [ElementType.METHOD, ElementType.FIELD])
public annotation ServerTimestamp

---

Annotation used to mark a timestamp field to be populated with a server timestamp. If a POJO being written contains null for a @ServerTimestamp-annotated field, it will be replaced with a server-generated timestamp.

Kotlin Note

When applying this annotation to a property of a Kotlin class, the @get use-site target should always be used. There is no need to use the @set use-site target as this annotation is only considered when writing instances into Firestore, and is ignored when reading instances from Firestore.

Here is an example of a class that can both be written into and read from Firestore whose foo property will be populated with the server timestamp in Firestore if its value is null:

data class Pojo(@get:ServerTimestamp var foo: Timestamp? = null) {
  constructor() : this(null) // Used by Firestore to create new instances
}

If the class only needs to be written into Firestore (and not read from Firestore) then the class can be simplified as follows:

data class Pojo(@get:ServerTimestamp val foo: Timestamp? = null)

That is, var can be tightened to val and the secondary no-argument constructor can be omitted.