Runtime fails to parse a valid ISO-8601 date

[m4p]

Context:

While testing my application that uses with swift-openapi-generator, I noticed that the runtime fails to parse ISO 8601 / RFC3339 compatible dates that use fractional seconds. E.g. "created_at": "2012-10-30T19:49:28.123286Z". While RFC3339 calls these "rarely used" in my experience they aren't that uncommon. For releated discussion see here.

I'd propose adding a fallback DateFormatter that uses [.withInternetDateTime, .withFractionalSeconds] as formatOptions like I did here. If this is agreeable, I can send a pull request.

$ swift --version
swift-driver version: 1.75.2 Apple Swift version 5.8.1 (swiftlang-5.8.0.124.5 clang-1403.0.22.11.100)
Target: arm64-apple-macosx13.0

$ uname -a
Darwin hayai.lan 22.5.0 Darwin Kernel Version 22.5.0: Mon Apr 24 20:52:24 PDT 2023; root:xnu-8796.121.2~5/RELEASE_ARM64_T6000 arm64

My system has IPv6 enabled.

[czechboy0]

Hi @m4p,

this is a property of the default behavior of Foundation's implementation of the ISO8601 date formatter.

You can provide your own date transcoding logic by implementing a custom DateTranscoder and providing that in the Configuration initializer.

The reason why I don't think we should automatically fall back to a second date formatter is because while this would help with being more flexible with which date strings are successfully decoded, it would create ambiguity on the encoding side – should it be encoded with or without the fractional seconds part?

Please try to implement a custom DateTranscoder and if that works for you, we can close this issue, as I don't currently think we should change anything. Thanks! 🙏

[m4p]

Can confirm supplying a custom DateTranscoder is a viable workaround. This ticket can be closed.

[sureshjoshi]

For anyone running into this ticket - here's a trivial example of setting this up. I have a situation where there are like 3-4 different date representations on the server, and my app has to handle it 🤦🏽

import OpenAPIRuntime
import OpenAPIURLSession

struct MyDateTranscoder: DateTranscoder {
    func encode(_ date: Date) throws -> String {
        ...
        return myEncodedDate
    }

    func decode(_ string: String) throws -> Date {
        let dateFormatters = [...]
        for formatter in dateFormatters {
            if let result = formatter.date(from: string) {
                return result
            }
        }
        throw DecodingError.dataCorrupted(.init(
            codingPath: [],
            debugDescription: "Date string does not match any of the expected formats"))
    }
}

...

return Client(
    serverURL: serverUrl,
    configuration: .init(dateTranscoder: MyDateTranscoder()),
    transport: URLSessionTransport(configuration: .init(session: session)),
    middlewares: [AuthenticationMiddleware(bearerToken: bearerToken)]
)

[yanniks]

I believe as well that the provided protocol is not sufficient to handle proper ISO-8601 (de-) serialization. More specifically, DateTranscoder at least needs the ability to differentiate between date and date-time (OpenAPI Guide).

Should this issue be re-opened to track Its progress?

[czechboy0]

@yanniks great point, we should not be using Foundation.Date for format: date, I filed an issue here to fix that: #136

[czechboy0]

This issue can stay closed, however, as it's tracking deserialization of a date-time.