Reading Firestore document metadata as struct fields

Firestore provides additional generated fields for each of document you create:

• _firestore_id: Generated document ID (when it is not specified from the client);
• _firestore_created: The time at which the document was created;
• _firestore_updated: The time at which the document was last changed;

To be able to read them the library makes them available as system fields for the Serde deserializer with reserved names, so you can specify them in your structures as:

use firestore::*;
use serde::{Deserialize, Serialize};
#[derive(Debug, Clone, Deserialize, Serialize)]
struct MyTestStructure {
    #[serde(alias = "_firestore_id")]
    id: Option<String>,
    #[serde(alias = "_firestore_created")]
    created_at: Option<FirestoreTimestamp>,
    #[serde(alias = "_firestore_updated")]
    updated_at: Option<FirestoreTimestamp>,
    some_string: String,
    one_more_string: String,
    some_num: u64,
}

Complete example available here.