Swift Codable Map Children by ID

Question

我有以下代码。

import Foundation

let jsonData = """
[
    {"id": "1", "firstname": "Tom", "lastname": "Smith", "age": "28"},
    {"id": "2", "firstname": "Bob", "lastname": "Smith"},
    {"id": "3", "firstname": "Jim", "lastname": "Smith", "parentid": "2"},
    {"id": "4", "firstname": "Ray", "lastname": "Smith", "parentid": "3"}
]
""".data(using: .utf8)!

class Person: Codable {
    let id: String
    let firstName, lastName: String
    let age: String?
    let parentid: String?
    let children: [Person]?

    enum CodingKeys : String, CodingKey {
        case firstName = "firstname"
        case lastName = "lastname"
        case age
        case parentid
        case id
    }

    init(from decoder: Decoder) throws {
        let values = try decoder.container(keyedBy: CodingKeys.self)
        firstName = try values.decode(String.self, forKey: .firstName)
        lastName = try values.decode(String.self, forKey: .lastName)
        age = try values.decodeIfPresent(String.self, forKey: .age)
        parentid = try values.decodeIfPresent(String.self, forKey: .parentid)
        id = try values.decodeIfPresent(String.self, forKey: .id)
    }

}

let decoded = try JSONDecoder().decode([Person].self, from: jsonData)
print(decoded)

所以我有 children 属性。我基本上希望 decoded 是一个包含 2 个 Person 对象(Tom 和 Bob)的数组。 decoded[1].children 应该是一个包含 1 个 Person 对象 (Jim) 的数组。 decoded[1].children[0] 应该是一个包含 1 个 Person 对象 (Ray) 的数组。

如何使用 Swift Codable 系统实现这一目标？

Answer 1

你可以这样做:

    if let decoded = try? JSONDecoder().decode([Person].self, from: jsonData)
    {
        for person in decoded
        {
            person.children = decoded.filter({ (child) -> Bool in
                return person.id == child.parentid
            })
        }
    }

在上面的代码中，在获得解码数组后，我只是使用for循环遍历它来识别每个的children人 如果存在的话。