将codable与有时为Int且有时为String的键一起使用 [英] Using codable with key that is sometimes an Int and other times a String

问题描述

我有一个API，该API有时会以Int的形式返回JSON中的特定键(在这种情况下为id)，而有时它会返回与String相同的键.如何使用可编码来解析该JSON?

I have an API that will sometimes return a specific key (in this case id) in the JSON as an Int and other times it will return that same key as a String. How do I use codable to parse that JSON?

struct GeneralProduct: Codable {
    var price:Double!
    var id:String?
    var name:String!

    private enum CodingKeys: String, CodingKey {
        case price = "p"
        case id = "i"
        case name = "n"
    }

    init(price:Double? = nil, id: String? = nil, name: String? = nil) {
        self.price = price
        self.id = id
        self.name = name
    }
}

我一直收到以下错误消息:Expected to decode String but found a number instead.它返回数字的原因是因为id字段为空，并且当id字段为空时，默认情况下将返回0作为ID(可编码的标识为数字).我基本上可以忽略ID密钥，但是codable并不能让我选择忽略它.处理此问题的最佳方法是什么?

I keep getting this error message: Expected to decode String but found a number instead. The reason that it returns a number is because the id field is empty and when the id field is empty it defaults to returning 0 as an ID which codable identifies as a number. I can basically ignore the ID key but codable does not give me the option to ignore it to my knowledge. What would be the best way to handle this?

这是JSON.超级简单

Here is the JSON. It is super simple

工作

{
  "p":2.12,
  "i":"3k3mkfnk3",
  "n":"Blue Shirt"
}

错误-因为系统中没有id，所以它将默认值返回0，可编码的代码显然将其视为与字符串相对的数字.

Error - because there is no id in the system, it returns 0 as a default which codable obviously sees as a number opposed to string.

{
  "p":2.19,
  "i":0,
  "n":"Black Shirt"
}

推荐答案

struct GeneralProduct: Codable {
    var price: Double?
    var id: String?
    var name: String?
    private enum CodingKeys: String, CodingKey {
        case price = "p", id = "i", name = "n"
    }
    init(price: Double? = nil, id: String? = nil, name: String? = nil) {
        self.price = price
        self.id = id
        self.name = name
    }
    init(from decoder: Decoder) throws {
        let container = try decoder.container(keyedBy: CodingKeys.self)
        price = try container.decode(Double.self, forKey: .price)
        name = try container.decode(String.self, forKey: .name)
        if let value = try? container.decode(Int.self, forKey: .id) {
            id = String(value)
        } else {
            id = try container.decode(String.self, forKey: .id)
        }
    }
}

---

let json1 = """
{
"p":2.12,
"i":"3k3mkfnk3",
"n":"Blue Shirt"
}
"""

let json2 = """
{
"p":2.12,
"i":0,
"n":"Blue Shirt"
}
"""

---

do {
    let product = try JSONDecoder().decode(GeneralProduct.self, from: Data(json2.utf8))
    print(product.price ?? "")
    print(product.id ?? "")
    print(product.name ?? "")
} catch {
    print(error)
}

---

编辑/更新:

当api返回0时，您也可以简单地将nil分配给id:

You can also simply assign nil to your id when your api returns 0:

if let _ = try? container.decode(Int.self, forKey: .id) {
    id = nil
} else {
    id = try container.decode(String.self, forKey: .id)
}

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