Flutter Firestore Server side Timestamp - dart

Question

I need to add a server side timestamp on new documents added to Firestore using a Flutter app. I see I am supposed to use FieldValue.serverTimestamp but I am not sure where to find this.

Answer 1

As of September 5th, the updated cloud_firestore v0.8.0 library now has FieldValue.serverTimestamp(). All is now well in the universe

Answer 2

'timestamp' : Timestamp.now()
Timestamp.now() is part of cloud_firestore;
Example
Screenshot showing that the library is imported from cloud_firestore, and creates a server-generated timestamp in the written data. Docs

Answer 3

Expanding on #spongyboss' answer (which works as of April 2020) by adding sample usage:
_firestore.collection('messages').add({
'text': messageText,
'sender': loggedInUser.email,
'created': FieldValue.serverTimestamp()
});
'created' will be stored as a timestamp
Sample sorting:
_firestore.collection('messages')
.orderBy('created', descending: false)
.snapshots()

Answer 4

If you are using a model class to set the data, then you should create a dynamic variable with some name. For mine it was 'createdDate'.
class Products {
Products({
this.data,
this.createdDate,
});
List<ProductItems>? data;
dynamic createdDate;
factory Products.fromJson(Map<String, dynamic> json) => Products(
data: List<ProductItems>.from(json["data"].map((x) => ProductItems.fromJson(x))),
createdDate: json["createdDate"],
);
Map<String, dynamic> toJson() => {
"data": List<dynamic>.from(data!.map((x) => x.toJson())),
"createdDate": createdDate
};
}
class ProductItems {
String? id;
String? name;
int? price;
int? quantity;
ProductItems({
this.price,
this.quantity,
this.name,
this.id,
});
ProductItems.fromJson(Map<String, dynamic> json) {
price = json['price'];
quantity = json['quantity'];
name = json['name'];
id = json['id'];
}
Map<String, dynamic> toJson() {
final Map<String, dynamic> data = <String, dynamic>{};
data['price'] = price;
data['quantity'] = quantity;
data['name'] = name;
data['id'] = id;
return data;
}
}
And during setting the data to firestore,
final CollectionReference _cart = _firestore.collection('cart');
final _cartReference = _cart.withConverter<Products>(
fromFirestore: (snapshot, _) => Products.fromJson(snapshot.data()!),
toFirestore: (userModel, _) => userModel.toJson(),
);
await _cartReference.doc(auth?.uid).set(Products(
data: productList.data,
createdDate: FieldValue.serverTimestamp(),
));