Firestore decode fails for an optional @ServerTimestamp field

[fanwgwg]

Description

Decoding a Firestore document into a Codable model with an optional field marked @ServerTimestamp (e.g., var myTimestamp: Timestamp?) fails if the field is absent in the document. This is commonly needed let's say we're adding a new server write timestamp to an existing data model.

Reproducing the issue

struct TestModel: Codable {
    @ServerTimestamp var optionalServerTs: Date?
    var regularOptional: String?
    var name: String
}

let docRef = db.collection("tests").document("missingOptionalTsDoc")
docRef.getDocument(as: TestModel.self) { result in
    // Decoding fails here if 'optionalServerTs' is missing
    // but 'regularOptional' (if missing) would correctly be nil.
}

Firebase SDK Version

11.12.0

Xcode Version

16.4

Installation Method

Swift Package Manager

Firebase Product(s)

Firestore

Targeted Platforms

iOS

Relevant Log Output

keyNotFound(CodingKeys(stringValue: "lastServerWriteTimestamp", intValue: nil), Swift.DecodingError.Context(codingPath: [], debugDescription: "No value associated with key CodingKeys(stringValue: \"lastServerWriteTimestamp\", intValue: nil) (\"lastServerWriteTimestamp\").", underlyingError: nil))

If using Swift Package Manager, the project's Package.resolved

No response

If using CocoaPods, the project's Podfile.lock

No response

[google-oss-bot]

I couldn't figure out how to label this issue, so I've labeled it for a human to triage. Hang tight.

[milaGGL]

Hi @fanwgwg, thank you for raising this issue. While I am looking into this, could you please try:

1. change the Date to Timestamp:

   firebase-ios-sdk/Firestore/Swift/Source/Codable/ServerTimestamp.swift

   Line 64 in 4f6c342

   /// @ServerTimestamp var ts: Timestamp?

2. give it a default nil value