如何用单个Decodable结构体解码两种键名不同的同结构JSON响应

核心思路是自定义Decodable的初始化逻辑，为存在键名差异的属性同时兼容两种键名，优先尝试匹配响应2的键，匹配失败时自动降级尝试匹配响应1的对应键即可。

完整实现代码 #

struct Verse: Decodable, Identifiable {
    let id: Int
    let book_name: String
    let book_id: Int
    let verse: String
    let verse_number: Int
    let chapter: Int // 数据库中的章节ID
    let chapter_number: Int

    // 定义两种响应中所有用到的键名
    enum CodingKeys: String, CodingKey {
        case id, verse, verse_number, chapter
        case book_name, chapter__book__name
        case book_id, chapter__book__id
        case chapter_number, chapter__chapter
    }

    init(from decoder: Decoder) throws {
        let container = try decoder.container(keyedBy: CodingKeys.self)
        // 无差异的字段直接解码
        id = try container.decode(Int.self, forKey: .id)
        verse = try container.decode(String.self, forKey: .verse)
        verse_number = try container.decode(Int.self, forKey: .verse_number)
        chapter = try container.decode(Int.self, forKey: .chapter)
        
        // 有键名差异的字段优先匹配响应2的键，失败则匹配响应1的键
        book_name = try container.decodeIfPresent(String.self, forKey: .book_name) 
            ?? container.decode(String.self, forKey: .chapter__book__name)
        book_id = try container.decodeIfPresent(Int.self, forKey: .book_id) 
            ?? container.decode(Int.self, forKey: .chapter__book__id)
        chapter_number = try container.decodeIfPresent(Int.self, forKey: .chapter_number) 
            ?? container.decode(Int.self, forKey: .chapter__chapter)
    }
}

说明 #

• 上述实现对上层业务完全透明，对外暴露的属性命名和你原来的定义完全一致，不需要修改现有调用逻辑
• 如果后续新增其他键名规则，只需要在CodingKeys中新增对应键，同时在初始化方法中增加对应的降级解码逻辑即可
• 若存在某个字段在两种响应中都可能为空的场景，可将对应属性修改为可选类型（如let book_name: String?），避免解码失败

内容的提问来源于stack exchange，提问作者erikvm