[Question] Working with optional about bettercodable

[AlexNsbmr]

Actually I fixed it with:

func decode<T>(_ type: OptionalDateValue<T>.Type, forKey key: Self.Key) throws -> OptionalDateValue<T> {
    return try decodeIfPresent(type, forKey: key) ?? OptionalDateValue<T>(wrappedValue: nil)
}

[igorkulman]

Same problem trying to apply @LosslessValue to an optional property.

[marksands]

As a workaround for now you can try:

struct S {
      var timestamp: DateValue<TimestampStrategy>?
}

You lose the property wrapper, but you can still get get the Date? from calling timestamp.wrappedValue. I don't think there's a good workaround without introducing a new PW type like @OptionalDateValue, unless anyone has suggestions. I'll think about it some.

[AlexNsbmr]

@marksands do you think it's possible to implement your solution: @OptionalDateValue<TimestampStrategy> var timestamp: Date?
Tried to work on it but dealing with empty data failure triggered by the public init(from decoder: Decoder) throws instantiation.

[marksands]

@AlexNsbmr You have to duplicate the strategy as well, which is why I don't want to pursue that implementation for this library. Here's a working example, you're welcome to use it https://gist.github.com/marksands/243cc6963aa4cf23a4d12ecc2b51f44a

[AlexNsbmr]

@marksands thanks you for your answer and your exemple.
Sorry, I wasn't very precise about what was not working. Actually it's working with:
let jsonData = #"{"timestamp": null}"#.data(using: .utf8)!
But not when the key is missing with an empty body for exemple:
let jsonData = #"{}"#.data(using: .utf8)!

giving the following error:

Thread 1: Fatal error: 'try!' expression unexpectedly raised an error: Swift.DecodingError.keyNotFound(CodingKeys(stringValue: "timestamp", intValue: nil), Swift.DecodingError.Context(codingPath: [], debugDescription: "No value associated with key CodingKeys(stringValue: \"timestamp\", intValue: nil) (\"timestamp\").", underlyingError: nil))

Maybe you have an idea how to achieve it but I don't think there is actually any solution

[marksands]

@AlexNsbmr in that case you can use the generic type by itself and fetch the internal wrappedValue for the optional date. Something like this:

struct Fixture: Codable {
  var timestamp: OptionalDateValue<OptionalTimestampStrategy>?
}

extension Fixture {
  var timestampDate: Date? {
    return timestamp?.wrappedValue
  }
}

[AlexNsbmr]

@marksands Yes it could work like that but we need to declare a second variable and the variable declaration is not homogeneous because we don't use the same notation.

Anyway, thank you for the suggestion and keep up the great work ! :)

Hope there will be some changes in Codable or in WrapperProperty in the future to allow such a notation.

[guidedways]

@AlexNsbmr Can you share the full solution?

[AlexNsbmr]

@guidedways yes sure, actually it's the same solution that @marksands suggested:

https://gist.github.com/marksands/243cc6963aa4cf23a4d12ecc2b51f44a

You just need to add #26 (comment) in addition to that

[SajjadKharrazi]

in my json sometimes exists timestamp and sometimes does not exist.
i want to have timestamp like this with Date() as default value if does not exist or is null:

struct Fixture: Codable {
  @OptionalDateValue<OptionalTimestampStrategy> var timestamp: Date
} 

how can i do this?