swift - delete or replace <null> values from nested dictionary - swift

Question

I have some data from server, and I'm using Alamofire SwiftyJSON to convert it to [String: Any]. Then I'm saving it to plist using SwiftyPlistManager. The point is that SwiftyPlistManager crashed when saving <null>, so I need to replace all <null>or nilto "".
My Dictionary after Alamofire SwiftyJSON looks this way:
["info_editable": true,
"name": Android Q,
"is_message": true,
"images": [["id": 92,
"image": /media/product/102.png]],
"video_description": <null>,
"is_valid": true]
or it could be -
["info_editable": true,
"name": Android Q,
"is_message": true,
"images": <null>,
"video_description": <null>,
"is_valid": true]
I suppose to use Codable from raw data, but have no idea how to set initial value as empty string or [[]], then check if parced data is <null> and leave initial value as default.
Or is there any way to list nested dictionary to replace <null>to ""?

Answer 1

You can try
var dic = ["1":nil,"2":"33","3":"5444"]
let res = dic.mapValues { $0 == nil ? "" : $0 }
print(res) // ["1": Optional(""), "2": Optional("33"), "3": Optional("5444")]

Answer 2

for now, my best idea is -
1) stringify every value except array of dictionaries,
2) check if string content "null", then replace it with ""if true.
3) array of dictionaries, if stringified, will have 2 option - with [[ and ]](then checking every dictionary like above) or without - in case of "images": <null>,(so <null> should be replaced with[[]].
but I have about 7 requests with different data, should be parsed this strange way, and I hope to found more pretty decision.

Answer 3

Here's a protocolish solution, that goes recursively through dictionaries and arrays:
/// Allows clients to ask the receiver to remove any `NSNull` instances
protocol NullStripable {
func strippingNulls() -> Self
}
extension Array: NullStripable {
func strippingNulls() -> Self {
return compactMap {
switch $0 {
case let strippable as NullStripable:
// the forced cast here is necessary as the compiler sees
// `strippable` as NullStripable, as we casted it from `Element`
return (strippable.strippingNulls() as! Element)
case is NSNull:
return nil
default:
return $0
}
}
}
}
extension Dictionary: NullStripable {
func strippingNulls() -> Self {
return compactMapValues {
switch $0 {
case let strippable as NullStripable:
// the forced cast here is necessary as the compiler sees
// `strippable` as NullStripable, as we casted it from `Value`
return (strippable.strippingNulls() as! Value)
case is NSNull:
return nil
default:
return $0
}
}
}
}
Usage example:
let dict: [String: Any] = [
"items": ["info_editable": true,
"name": "Android Q",
"is_message": true,
"images": [["id": 92,
"image": "/media/product/102.png"]],
"video_description": NSNull(),
"is_valid": true],
"somethingElse": NSNull()
]
print(dict.strippingNulls())
Sample output:
["items": ["name": "Android Q", "info_editable": true, "images": [["image": "/media/product/102.png", "id": 92]], "is_message": true, "is_valid": true]]

Answer 4

Try this one. It will remove null and replace with blank string, without loosing key.
func removeNullFromResponse(response:NSDictionary) -> NSDictionary{
let blankString = "\"\""
let myMutableDict: NSMutableDictionary = NSMutableDictionary(dictionary: response)
var data = try? JSONSerialization.data(withJSONObject:myMutableDict, options: JSONSerialization.WritingOptions.prettyPrinted)
var strData = NSString.init(data: data!, encoding:String.Encoding.utf8.rawValue)
strData = strData?.replacingOccurrences(of: "<NULL>", with: blankString) as NSString?
strData = strData?.replacingOccurrences(of: "<null>", with: blankString) as NSString?
strData = strData?.replacingOccurrences(of: "<Null>", with: blankString) as NSString?
strData = strData?.replacingOccurrences(of: "NULL", with: blankString) as NSString?
strData = strData?.replacingOccurrences(of: "null", with: blankString) as NSString?
data = strData?.data(using: String.Encoding.utf8.rawValue)!
var dictionary = NSDictionary()
do
{
dictionary = try JSONSerialization.jsonObject(with: data! , options: JSONSerialization.ReadingOptions()) as! NSDictionary
} catch {
print(error)
}
return dictionary as NSDictionary
}