如何为动态键创建模型，json 解析，swift5

Question

我正在解析 json 数据并尝试创建模型，但无法弄清楚如何实现标题并从 json 数据（我提供的数据）中提取属性，因为 pageids 属性是动态的。请告诉我如何创建模型以使用 id（存储在 pageids 属性）

从页面中提取 title 属性

link 对于 json 数据 https://en.wikipedia.org/w/api.php?exintro=&titles=canterbury%20bells&indexpageids=&format=json&pithumbsize=500&explaintext=&redirects=1&action=query&prop=extracts%7Cpageimages

我试了一下，下面是我的代码，但我认为那不正确

var ID = ""
struct Document:Codable {
    
    let batchcomplete:String
    let query:Query
}
struct Query:Codable {
    let normalized:[Normalized]
    
    let pages:Pages
    
    var pageids:[String]{
        didSet{
            ID = oldValue[0]
        }
    }
    
}

struct Normalized:Codable {
    let from:String
    let to:String // it is a name of an flower
}
struct Pages:Codable {
    let id:[Pages2]
    enum CodingKeys:CodingKey {
        case id = "\(ID)"
    }
}
struct Pages2:Codable {
    let title:String // this is an official name of flower
    let extract:String // this is a body
    let thumbnail:Thumbnail
}
struct Thumbnail:Codable {
    let source:String //this is an url for photo
}

Answer 1

映射您的 JSON 的模型将是这样的：

struct Document: Codable {
    let batchcomplete: String
    let query: Query
}

struct Query: Codable {
    let normalized: [Normalized]
    var pageids: [String]
    let pages: [String: Page]
}

struct Normalized: Codable {
    let from: String
    let to: String
}

struct Page: Codable {
    let title: String
    let extract: String
    let thumbnail: Thumbnail
}
struct Thumbnail: Codable {
    let source: String
}

并且您可以使用 pageids 数组和 pages 字典访问每个页面：

let decoder = JSONDecoder()
do {
    let decoded = try decoder.decode(Document.self, from: Data(jsonString.utf8))
    decoded.query.pageids.forEach { id in
        guard let page = decoded.query.pages[id] else { return }
        print(page.title)
    }
} catch {
    print(error)
}

不过，我更愿意对模型进行一些小改动，以便更轻松地访问页面。这将需要自定义实现 Query struct:

的解码

struct Query: Decodable {
    let normalized: [Normalized]
    let pages: [Page]
    
    enum CodingKeys: String, CodingKey {
        case normalized
        case pageids
        case pages
    }
    
    init(from decoder: Decoder) throws {
        let container = try decoder.container(keyedBy: CodingKeys.self)
        normalized = try container.decode([Normalized].self, forKey: .normalized)
        
        let pageids = try container.decode([String].self, forKey: .pageids)
        let pagesDict = try container.decode([String: Page].self, forKey: .pages)
        pages = pageids.compactMap { pagesDict[[=12=]] }
    }
}

那么，访问每个页面就像循环一样简单：

let decoder = JSONDecoder()
do {
    let decoded = try decoder.decode(Document.self, from: Data(jsonString.utf8))
    decoded.query.pages.forEach { page in
        print(page.title)
    }
} catch {
    print(error)
}

如何为动态键创建模型，json 解析，swift5

How to create a Model for dynamic keys , json parsing ,swift5

xcode

json

ios

swift

codable