swift - 从嵌套字典中删除或替换 <null> 值

Posted 2023-03-15

【中文标题】swift - 从嵌套字典中删除或替换 <null> 值

【英文标题】：swift - delete or replace <null> values from nested dictionary

【发布时间】：2019-09-30 13:29:45

【问题描述】：

我有一些来自服务器的数据，我正在使用Alamofire SwiftyJSON 将其转换为[String: Any]。然后我使用SwiftyPlistManager 将其保存到 plist。重点是SwiftyPlistManager在保存<null>的时候崩溃了，所以我需要把<null>或者nil全部替换成""。

Alamofire SwiftyJSON 之后的我的字典是这样的：

["info_editable": true,
 "name": android Q,
 "is_message": true,
 "images": [["id": 92,
             "image": /media/product/102.png]],
 "video_description": <null>,
 "is_valid": true]

或者它可能是-

["info_editable": true,
 "name": Android Q,
 "is_message": true,
 "images": <null>,
 "video_description": <null>,
 "is_valid": true]

我想从原始数据中使用Codable，但不知道如何将初始值设置为空字符串或[[]]，然后检查parced数据是否为<null>并将初始值保留为默认值。 或者有没有办法列出嵌套字典来替换<null>to ""？

【问题讨论】：

var updatedDictionary = Dictionary(uniqueKeysWithValues: yourDictionary.map ($0, $1 != nil ? $1! : "") )

【参考方案1】：

你可以试试

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")]

【参考方案2】：

目前，我最好的想法是 -

1) 字符串化除字典数组之外的每个值，

2) 检查字符串内容是否为“null”，然后将其替换为""如果为真。

3) 字典数组，如果字符串化，将有 2 个选项 - 使用 [[ 和 ]]（然后像上面一样检查每个字典）或不使用 - 如果是 "images": <null>,（所以 <null> 应该被替换与[[]]。 但是我有大约 7 个不同数据的请求，应该以这种奇怪的方式解析，我希望找到更漂亮的决定。

【参考方案3】：

这是一个协议解决方案，它递归地通过字典和数组：

/// 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
            
        
    

使用示例：

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())

样本输出：

["items": ["name": "Android Q", "info_editable": true, "images": [["image": "/media/product/102.png", "id": 92]], "is_message": true, "is_valid": true]]

【参考方案4】：

试试这个。它将删除 null 并替换为空白字符串，而不会丢失密钥。

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

【讨论】：

这是一个非常不切实际的解决方案。如果任何值包含替换对象怎么办，例如Vanilla 包含 nil，该值将被替换为空白字符串并返回错误。