Returning JSONValue instead of JSONValue? from subscript is not Swift-style about swiftyjson

[lingoer]

Well, I don't think so.
In my opinion, retrieving value with subscript is still in the context of JSON,when and only when the time you try to cast the real value out from JSON should then be an Optional.
Additionally it also makes it possible to trace the breaking point of the subscript chain.

[pvwoods]

Whenever a subscript object can not be guaranteed to exist, it would seem logical to cast it as an optional in order to avoid people assuming that it should exist. This is an issue that JSON is specifically susceptible to since people will often treat elements of a JSON object as being required, when in reality, it can only be assumed that it will usually exist, though it is not guaranteed.

[mogocat]

I think that if the value exists, the code returns the value, if not, the code returns something about which subscript is nil. This may be very helpful when my json data has many levels. For example:{foo:{bar:{x:{y:"value"}}}}. When I type some code like: json['foo']['bar']['z']['y'].string, I want to know that the subscript "z" isn't exist, not only return nil.

[LukeTangPL]

@liuchunyao90 try this

if let string = json['foo']['bar']['z']['y'].string {
    // do something you like
} else {
    // print the error
   println(json['foo']['bar']['z']['y'])
}

or

if let error = json["a"]["b"]["c"]["d"][0].error {
     //done. the json is the same like you expect
} else {
    // print the error
    println(error)
}

[k06a]

Maybe it will be nice to use library like this?

switch (json['foo']['bar']['z']['y'].stringOrError()) {
case .Error(let error):
    break;
case .Some(let some):
    break;
}

this method should be like this:

func stringOrError() -> OptionalError<String>

where OptionalError should be like this:

enum OptionalError<T> {
    case Error(NSError)
    case Some(T)
}

[k06a]

@FlappyHeart you really need to know this in run time? Structure format should be selected in compile time mostly.