String parsing

[alexmarchant]

Cool library!

Having trouble getting the right output from string input:

var json = JSONValue("{\"a\":\"b\"}") // (Enum Value)
json == JSONValue.JInvalid // false
json["a"].string // nil

[delebedev]

Interesting use case! Why do you expect to achieve from this input, a dictionary, right?
Why don't you specify [a: b] (a dictionary) as an input?

[lingoer]

Interesting
@garnett Shall we introduce some LiteralConvertible Protocol or some other init method?

[alexmarchant]

I was just using it to play around with in a Playground to see how JSONValue's worked. From the source it looked like JSONValue() took String input so I tried it out. Haha, now after reading your reply I get that JSONValue's hold individual element data and that it wasn't meant to parse string input.

Ya, that was confusing to me, i'd recommend making a separate init that only takes NSData or allowing String input as well.

[delebedev]

I've thought about implementing literalConvertibles, but It's not the case where it will help. If we implement convertible, the call will look like:
let value : JSONValue = [1, :"Foo"]
By manually specifying the type, we allow to assign the value omitting the constructor (now it looks like let value = JSONValue([1, :"Foo"])

[delebedev]

Ya, that was confusing to me, i'd recommend making a separate init that only takes NSData or allowing String input as well.
Good point! @lingoer we should rethink public API and use cases of the library. Accepting both primitive types and NSData as well really looks confusing.

Maybe, it will be better to make the following public api:

• fromObject - converts json from NSJSONSerialization result
• fromData - which internally uses NSJSONSerialization to get object representation.

This will allow us to keep these two use cases separated

[lingoer]

Agreed! :)
Yesterday, I've replied a similar question in a Chinese forum with a similar answer to you.
I think a class func parseFromString() is also needed

[delebedev]

As addition to previous comment: I personally do not like .JInvalid as return value.
let value = JSONValue(...) if value != .JInvalid { ... some logic here }

For me, it looks more natural to return here something like fancy optional wrapper: http://swiftlytyping.tumblr.com/post/88210131086/error-handling
It can return both Error and JSONValue

[delebedev]

@lingoer it will be really pain to implement, regexp all the things? I still do not see any real-world usage for this

[lingoer]

An ugly implementation would be String => NSData => NSJSONSerialization, ugly, but worked?
As for JInvalid :

    case JNumber(Double)
    case JString(String)
    case JBool(Bool)
    case JNull
    case JArray(Array<JSONValue>)
    case JObject(Dictionary<String,JSONValue>)
    case JInvalid(NSError)

[delebedev]

I like JInvalid(NSError), let's keep this

[lingoer]

Ok, I'll commit the JInvalid thing later and think awhile for the init method. I want to keep NSData as the default init ,while provide some other init method for other types

[gcmartijn]

Could someone give a example how to parse these JSON strings ?

Received_JSON_string: {"a":"actionvalue"}

let json = JSON(Received_JSON_string)
let action = json["a"].stringValue
println("Received a: (action)") // must give me the actionvalue

[lobodart]

let json: JSON = JSON(data: Received_JSON_string.dataUsingEncoding(NSUTF8StringEncoding, allowLossyConversion: true)!)
let action = json["a"].stringValue
println("Received a: \(action)")

[gcmartijn]

@lobodart Works !