struct AStudent: Codable {
init(from decoder: Decoder) throws {
let container = try decoder.container(keyedBy: CodingKeys.self)
self.aID = try container.decode(String.self, forKey: .aID)
self.aName = try container.decode(String.self, forKey: .aName)
let gradeDecoded = try container.decode(Double.self, forKey: .aGrade)
self.AGrede = Int(gradeDecoded)
}
enum CodingKeys: String, CodingKey {
case aName = "name"
case aGrade = "grade"
case aID = "id"
}
var aID: String
var aName: String
var AGrede: Int
func encode(to encoder: Encoder) throws {
var container = encoder.container(keyedBy: CodingKeys.self)
try container.encode(aID, forKey: .aID)
try container.encode(Double(AGrede), forKey: .aGrade)
try container.encode(aName, forKey: .aName)
}
}struct Student: SuperCodable {
@Keyed
var id: String
@Keyed("name")
var aName: String
@KeyedTransform("grade", doubleTransform)
var AGrade: Int
}
let doubleTransform = SCTransformOf<Int, Double> {
(double) -> Int in
Int(double)
} toEncoder: { (int) -> Double in
Double(int)
}- Working with Nested
Foundation.Codableproperty
- SuperDecoable must construct from nothing
init() @Keyed var id:Intwill do O(n) calculation on underlaying wrapper_VARIABLE_NAMEinto keyVARIABLE_NAME. Be ware of variable name takes too long
- Every property in a SuperCodable should a
DecodableKey/EncodableKey, otherwise the property(which should beCodable) will simply ignored during the Codable process.
Why:
Basically Mirror can't mutating the object value during the
init(from decoder:) throws, since we create the object fromself.init()
-
Inspired by: https://medium.com/trueid-developers/combined-propertywrapper-with-codable-swift-368dc4aa2703
-
Try to merge
@KeyedTransforminto@Keyed, but it required@Keyed var id: Stringto be@Keyed() var id: String, with extra()🧐 -
Swift should auto generate
STRUCT.init(....)for you, but if you using@Keyed var id: Stringwithout default value, it will generateinit(id: Keyed<String>), by giving default value@Keyed var id: String = ""should solve this problem.
@Keyed var id:String?will cause fatalError on force unwrappingKeyed.value?, you can using@OptionalKeyedto make it works.OptionalKeyedmay / may not a good name, I am thinking of make the easy to change, maybeKeyedOptionalis EASY change? 🤔