可以解码Swift中可以和数组或单个元素的JSON数据吗? [英] Hot to decode JSON data that could and array or a single element in Swift?

问题描述

我有一个名为Info的结构，该结构根据接收到的数据进行解码.但有时，数据中的值之一可以是double或double数组.我该如何设置我的结构?

I have a struct named Info which is decoded based on the data it receives. But sometimes, one of the values in data can either be a double or an array of double. How do I set up my struct for that?

struct Info: Decodable {
    let author: String
    let title: String
    let tags: [Tags]
    let price: [Double]
    enum Tags: String, Decodable {
        case nonfiction
        case biography
        case fiction
    }
}

---

根据网址，我要么获得双倍价格

---

Based on the url, I either get price as a double

{
    "author" : "Mark A",
    "title" : "The Great Deman",
    "tags" : [
      "nonfiction",
      "biography"
    ],
    "price" : "242"

}

---

或者我将其作为双打数组

---

or I get it as an array of doubles

{
    "author" : "Mark A",
    "title" : "The Great Deman",
    "tags" : [
      "nonfiction",
      "biography"
    ],
    "price" : [
    "242",
    "299",
    "335"
    ]

}

---

我想设置我的结构，以便如果我收到一个double而不是一个double数组，则应该将price解码为1个double的数组.

---

I want to setup my struct so that if I receive a double instead of an array of doubles, price should be decoded as an array of 1 double.

推荐答案

您的JSON实际上是字符串或字符串数​​组.因此，您需要创建一个自定义解码器进行解码，然后将其转换为Double:

Your JSON actually is either a String or an array of Strings. So you need to create a custom decoder to decode and then convert them to Double:

struct Info {
    let author, title: String
    let tags: [Tags]
    let price: [Double]
    enum Tags: String, Codable {
        case nonfiction, biography, fiction
    }
}

---

extension Info: Codable {
    public init(from decoder: Decoder) throws {
        let container = try decoder.container(keyedBy: CodingKeys.self)
        author = try container.decode(String.self, forKey: .author)
        title  = try container.decode(String.self, forKey: .title)
        tags = try container.decode([Tags].self, forKey: .tags)
        do {
            price = try [Double(container.decode(String.self, forKey: .price)) ?? .zero]
        } catch {
            price = try container.decode([String].self, forKey: .price).compactMap(Double.init)
        }
    }
}

---

游乐场测试

---

Playground testing

let infoData = Data("""
{
    "author" : "Mark A",
    "title" : "The Great Deman",
    "tags" : [
      "nonfiction",
      "biography"
    ],
    "price" : "242"

}
""".utf8)
do {
    let info = try JSONDecoder().decode(Info.self, from: infoData)
    print("price",info.price)  // "price [242.0]\n"
} catch {
    print(error)
}

---

let infoData2 = Data("""
{
    "author" : "Mark A",
    "title" : "The Great Deman",
    "tags" : [
      "nonfiction",
      "biography"
    ],
    "price" : [
    "242",
    "299",
    "335"
    ]

}
""".utf8)

do {
    let info = try JSONDecoder().decode(Info.self, from: infoData2)
    print("price",info.price)  // "price [242.0, 299.0, 335.0]\n"
} catch {
    print(error)
}

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