DocumentId

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

Annotation used to mark a POJO property to be automatically populated with the document's ID when the POJO is created from a Cloud Firestore document (for example, via toObject).

Any of the following will throw a runtime exception:

  • This annotation is applied to a property of a type other than String or DocumentReference.
  • This annotation is applied to a property that is not writable (for example, a Java Bean getter without a backing field).
  • This annotation is applied to a property with a name that conflicts with a read document field. For example, if a POJO has a field `firstName` annotated by @DocumentId, and there is a property from the document named `firstName` as well, an exception is thrown when you try to read the document into the POJO via toObject or get.

When using a POJO to write to a document (via set or @set), the property annotated by @DocumentId is ignored, which allows writing the POJO back to any document, even if it's not the origin of the POJO.