如何将Realm对象转换为嵌套NSDate属性的JSON?
问题描述:
我有一个嵌套的Realm对象,在嵌套对象中有多个嵌套的NSDate
属性。我正在使用this answer将嵌套的Realm对象转换为NSDictionary
,但我不知道如何将该NSDictionary
转换为实际的JSON。如何将Realm对象转换为嵌套NSDate属性的JSON?
当我使用NSJSONSerialization.dataWithJSONObject()
,我得到的错误:'Invalid type in JSON write (__NSTaggedDate)'
据我了解,我必须先将NSDate
属性转换为NSString
。问题是我不知道如何进入深度嵌套的对象来做到这一点。
此代码生成'Invalid type in JSON write (__NSTaggedDate)'
错误:
let exercises = realm.objects(ExerciseProgram).first
let dic = exercises!.toDictionary()
do {
if let postData: NSData = try NSJSONSerialization.dataWithJSONObject(dic, options: NSJSONWritingOptions.PrettyPrinted) {
let json = NSString(data: postData, encoding: NSUTF8StringEncoding)! as String
print(json)
}
} catch let error as NSError {
print(error)
我的物体的简化版本:
final class ExerciseProgram: Object {
dynamic var name: String = ""
dynamic var startDate = NSDate()
dynamic var userProfile: User?
var program = List<Exercise>()
}
final class Exercise: Object {
dynamic var name = ""
dynamic var notes: String?
var workoutDiary = List<Workout>()
dynamic var goal = 0
}
final class Workout: Object {
dynamic var date = NSDate()
var sets = List<WorkSet>()
}
答
JSON序列与iOS”默认串行器是相当严格的,并且大多数类型(包括NSDate
)不能直接序列化。
我看了一下Eugene在这个问题中发布的令人敬畏的代码示例(看起来实际上是从另一个原始问题中派生出来的)。对象的深度似乎并不重要,因为看起来这个扩展巧妙地设置为在较低级别上递归地调用它自己。
现在,它只是简单地将NSDate
值复制到字典中,但您可以轻松地将其他情况添加到条件列表中,以检测任何NSDate
对象,并将它们转换为字符串。这会自动覆盖已经在字符串版本中的NSDate
值:
extension Object {
func toDictionary() -> NSDictionary {
let properties = self.objectSchema.properties.map { $0.name }
let dictionary = self.dictionaryWithValuesForKeys(properties)
let mutabledic = NSMutableDictionary()
mutabledic.setValuesForKeysWithDictionary(dictionary)
for prop in self.objectSchema.properties as [Property]! {
// find lists
if let nestedObject = self[prop.name] as? Object {
mutabledic.setValue(nestedObject.toDictionary(), forKey: prop.name)
} else if let nestedListObject = self[prop.name] as? ListBase {
var objects = [AnyObject]()
for index in 0..<nestedListObject._rlmArray.count {
let object = nestedListObject._rlmArray[index] as AnyObject
objects.append(object.toDictionary())
}
mutabledic.setObject(objects, forKey: prop.name)
}
else if let dateObject = self[prop.name] as? NSDate {
let dateString = ... ; //Perform the conversion you want here
mutabledic.setValue(dateString, forKey: prop.name)
}
}
return mutabledic
}
}