如何对对象内部的对象使用 Codable 编码

Question

我正在使用我的对象负载处理 JSON 负载。但我在对象内部编码对象时遇到问题。

我的 Payload class 是这个

class ConversationPayload :BaseObject {
    var title : String? = ""
    var messageDict: MessagePayload = MessagePayload()
    var participants: [Int32] = []
    var type: String = ""
    
    enum CodingKeys: String, CodingKey {
        case title = "title"
        case messageDict = "message"
        case participants = "participants"
        case type = "type"
    }

    override func encode(to encoder: Encoder) throws {
        var container = encoder.container(keyedBy: CodingKeys.self)
        if title != nil {
            try container.encode(title, forKey: .title)
        }
        try container.encode(messageDict, forKey: .messageDict)
        try container.encode(participants, forKey: .participants)
        try container.encode(type, forKey: .type)
    }
    
}

class MessagePayload: BaseObject {
    var body : String = ""
    var isVideocallInvite: Bool = false
    var attachmentsPayload: MessageAttachmentPayload? = nil
    
    enum CodingKeys: String, CodingKey {
        case body = "body"
        case isVideocallInvite = "is_videocall_invite"
        case attachmentsPayload = "attachment"
    }

    override func encode(to encoder: Encoder) throws {
        var container = encoder.container(keyedBy: CodingKeys.self)
        try container.encode(body, forKey: .body)
        try container.encode(isVideocallInvite, forKey: .isVideocallInvite)
        if attachmentsPayload != nil {
            try container.encode(attachmentsPayload, forKey: .attachmentsPayload)
        }
        
    }
}

class MessageAttachmentPayload: BaseObject {
    var photo : String = ""
    var photoType : String = "jpg"
}

BaseObject 是这个

class BaseObject:Codable{}

我想在 json 有效载荷中得到的是这样的

{"message": {"body": "body_string", "is_videocall_invite": 1}, "participants" : [user-id], "type" : "converstation_type","title":"title"}

有人知道我的负载有什么问题吗class？在 Codable 上还不是很熟悉。提前致谢。

Answer 1

问题是什么？我刚刚测试了你的 class，它有一些小问题，但它确实符合可编码的标准，并且编码没有问题。

操场上：

var conversation = ConversationPayload()
var message = MessagePayload()
message.body = "message body"
message.isVideocallInvite = true
var attachment = MessageAttachmentPayload()
attachment.photo = "attachment_file"
message.attachmentsPayload = attachment
conversation.messageDict = message
conversation.title = "Title"
conversation.participants = [1, 2, 3, 4]
conversation.type = "Conversation Type"

let encoder = JSONEncoder()
encoder.outputFormatting = .prettyPrinted
let data = try! encoder.encode(conversation)
print(String(data: data, encoding: .utf8)!)

输出如下所示：

{
  "participants" : [
    1,
    2,
    3,
    4
  ],
  "message" : {
    "is_videocall_invite" : true,
    "attachment" : {
      "photo" : "attachment_file",
      "photoType" : "jpg"
    },
    "body" : "message body"
  },
  "title" : "Title",
  "type" : "Conversation Type"
}

我在 MessageAttachmentPayload class 中添加了 encode 和 CodingKey 来对值进行编码。

这不正是您所期待的吗？

Answer 2

我不确定你在这里有什么限制，但我会简化所有这些。使 JSON 数据模型尽可能接近 JSON。

struct ConversationJsonModel: Codable {
    var title: String?
    var message: MessageJsonModel
    var participants: [Int]
    var type: String
}

struct MessageJsonModel: Codable {
    var body: String
    var is_videocall_invite: Int
    var attachment: AttachmentJsonModel?
}

struct AttachmentJsonModel: Codable {
    var photo: String
    var photo_type: String // <-- assuming photo_type is the JSON member name.
}

如果您需要视图模型或其他类型的本地数据模型，那么这两部分是分开的。

class BaseObject {}

class ConversationPayload: BaseObject {
    var title : String? = ""
    var messageDict: MessagePayload = MessagePayload()
    var participants: [Int32] = []
    var type: String = ""

    func makeConversationJsonModel() -> ConversationJsonModel {
        ConversationJsonModel(title: title,
                              message: messageDict.makeMessageJsonModel(),
                              participants: participants.map { Int([=11=]) },
                              type: type)
    }
}

class MessagePayload: BaseObject {
    var body : String = ""
    var isVideocallInvite: Bool = false
    var attachmentsPayload: MessageAttachmentPayload? = nil

    func makeMessageJsonModel() -> MessageJsonModel {
        MessageJsonModel(body: body,
                         is_videocall_invite: isVideocallInvite ? 1 : 0,
                         attachment: attachmentsPayload?.makeAttachmentJsonModel())
    }
}

class MessageAttachmentPayload: BaseObject {
    var photo : String = ""
    var photoType : String = "jpg"

    func makeAttachmentJsonModel() -> AttachmentJsonModel {
        AttachmentJsonModel(photo: photo, photo_type: photoType)
    }
}

最后，对您的 JSON

进行编码

let conversationPayload = ConversationPayload()
let json = try? JSONEncoder().encode(conversationPayload.makeConversationJsonModel())

这允许 JSON 表示和有效载荷模型之间的清晰分离。例如，在JSON中，is_videocall_invite是一个Int（0或1）；同时，在有效负载模型中，isVideocallInvite 是 Bool.

如何对对象内部的对象使用 Codable 编码

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