当属性类型可能从 Int 更改为 String 时，如何使用 Decodable 协议解析 JSON? [英] How to parse JSON with Decodable protocol when property types might change from Int to String?

问题描述

我必须解码具有大结构和大量嵌套数组的 JSON.我已经在我的 UserModel 文件中复制了该结构，并且它可以工作，但嵌套数组(位置)中的一个属性(邮政编码)有时是 Int，而其他一些是 String.我不知道如何处理这种情况并尝试了很多不同的解决方案.我试过的最后一个来自这个博客

任何帮助或任何不同的方法将不胜感激.API 调用是这样的:https://api.randomuser.me/?results=100&seed=xmoba这是我的用户模型文件:

导入基础导入 UIKit导入对象映射器struct PostModel: Equatable, Decodable{静态功能==(lhs:PostModel，rhs:PostModel)->布尔{如果 lhs.userId != rhs.userId {返回假}如果 lhs.id != rhs.id {返回假}如果 lhs.title != rhs.title {返回假}如果 lhs.body != rhs.body {返回假}返回真}var userId : Int变量 id : 整数变量标题:字符串变量体:字符串枚举键:CodingKey {案例用户ID案例ID案例标题箱体}init(来自解码器:解码器)抛出{让容器 = 尝试decoder.container(keyedBy: key.self)让 userId = 尝试 container.decode(Int.self, forKey: .userId)让 id = 尝试 container.decode(Int.self, forKey: .id)let title = try container.decode(String.self, forKey: .title)让 body = try container.decode(String.self, forKey: .body)self.init(userId: userId, id: id, title: title, body: body)}init(userId: Int, id: Int, title: String, body: String) {self.userId = 用户 IDself.id = idself.title = 标题self.body = 身体}初始化?(地图:地图){self.id = 0self.title = ""self.body = ""self.userId = 0}}扩展 PostModel:可映射 {变异功能映射(地图:地图){id <- 地图 ["id"]标题<-地图[标题"]身体 <- 地图 [身体"]用户 ID <- 地图 [用户 ID"]}}

解决方案

你可以像这样使用泛型:

enum {案例左(L)大小写正确(R)}扩展任一:可解码其中 L:可解码，R:可解码 {init(来自解码器:解码器)抛出{让容器 = 尝试decoder.singleValueContainer()如果让左=尝试?容器.解码(L.self){self = .left(left)} else if let right = try?容器.解码(R.self){self = .right(right)} 别的 {throw DecodingError.typeMismatch(Either<L, R>.self, .init(codingPath:decoder.codingPath, debugDescription: "Expected or `\(L.self)` 或 `\(R.self)`"))}}}扩展名:Encodable 其中 L:Encodable，R:Encodable {func encode(to encoder: Encoder) 抛出 {var 容器 = 编码器.singleValueContainer()切换自我{case let .left(left):尝试 container.encode(左)case let .right(right):尝试 container.encode(右)}}}

然后声明 postcode:Either<Int, String> 并且如果您的模型是 Decodable 并且所有其他字段都是 Decodable 也没有额外的需要代码.

I have to decode a JSON with a big structure and a lot of nested arrays. I have reproduced the structure in my UserModel file, and it works, except with one property (postcode) that is in a nested array (Location) that sometimes is an Int and some other is a String. I don't know how to handle this situation and tried a lot of different solutions. The last one I've tried is from this blog https://agostini.tech/2017/11/12/swift-4-codable-in-real-life-part-2/ And it suggests using generics. But now I can't initialize the Location object without providing a Decoder():

Any help or any different approach would be appreciated. The API call is this one: https://api.randomuser.me/?results=100&seed=xmoba This is my UserModel File:

import Foundation
import UIKit
import ObjectMapper

struct PostModel: Equatable, Decodable{

    static func ==(lhs: PostModel, rhs: PostModel) -> Bool {
        if lhs.userId != rhs.userId {
            return false
        }
        if lhs.id != rhs.id {
            return false
        }
        if lhs.title != rhs.title {
            return false
        }
        if lhs.body != rhs.body {
            return false
        }
        return true
    }


    var userId : Int
    var id : Int
    var title : String
    var body : String

    enum key : CodingKey {
        case userId
        case id
        case title
        case body
    }

    init(from decoder: Decoder) throws {
        let container = try decoder.container(keyedBy: key.self)
        let userId = try container.decode(Int.self, forKey: .userId)
        let id = try container.decode(Int.self, forKey: .id)
        let title = try container.decode(String.self, forKey: .title)
        let body = try container.decode(String.self, forKey: .body)

        self.init(userId: userId, id: id, title: title, body: body)
    }

    init(userId : Int, id : Int, title : String, body : String) {
        self.userId = userId
        self.id = id
        self.title = title
        self.body = body
    }
    init?(map: Map){
        self.id = 0
        self.title = ""
        self.body = ""
        self.userId = 0
    }
}

extension PostModel: Mappable {



    mutating func mapping(map: Map) {
        id       <- map["id"]
        title     <- map["title"]
        body     <- map["body"]
        userId     <- map["userId"]
    }

}

解决方案

You can use generic like this:

enum Either<L, R> {
    case left(L)
    case right(R)
}

extension Either: Decodable where L: Decodable, R: Decodable {
    init(from decoder: Decoder) throws {
        let container = try decoder.singleValueContainer()
        if let left = try? container.decode(L.self) {
            self = .left(left)
        } else if let right = try? container.decode(R.self) {
            self = .right(right)
        } else {
            throw DecodingError.typeMismatch(Either<L, R>.self, .init(codingPath: decoder.codingPath, debugDescription: "Expected either `\(L.self)` or `\(R.self)`"))
        }
    }
}

extension Either: Encodable where L: Encodable, R: Encodable {
    func encode(to encoder: Encoder) throws {
        var container = encoder.singleValueContainer()
        switch self {
        case let .left(left):
            try container.encode(left)
        case let .right(right):
            try container.encode(right)
        }
    }
}

And then declare postcode: Either<Int, String> and if your model is Decodable and all other fields are Decodable too no extra code would be needed.

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