[英]Swift Decode unique keys in JSON or ignore certain keys
I'm practicing my Swift skills, this time I'm trying to make a Covid-19 tracker, and for this I found this API , the thing is, that the format retrieved by /cases
is something like this (changing keys to make it more readable)我正在练习我的 Swift 技能,这次我正在尝试制作一个 Covid-19 跟踪器,为此我找到了这个API ,问题是/cases
检索到的格式是这样的(更改密钥以使它更具可读性)
{
"Country1": {
"All": {
"property1": 0,
"property2": "foo"
}
}, {
"All": {
"property1": "0",
"property2": "bar",
},
"State1": {
"property1": 0,
"property3": "foobar"
}
}
}
And I made the following structs to decode it:我做了以下结构来解码它:
Country国家
struct Country: Codable {
let All: [String: All]
private enum CodingKeys: String, CodingKey {
case All
}
}
All全部
struct All: Codable {
let confirmed: Int?
let recovered: Int?
let deaths: Int?
let country: String?
let population: Int?
let squareKmArea: Int?
let lifeExpectancy: String?
var elevationInMeters: String?
let continent: String?
let location: String?
let iso: String?
let capitalCity: String?
let lat: String?
let long: String?
let updated: String?
private enum CodingKeys: String, CodingKey {
case confirmed
case recovered
case deaths
case country
case population
case squareKmArea = "sq_km_area"
case lifeExpectancy = "life_expectancy"
case elevationInMeters = "elevation_in_meters"
case continent
case location
case iso
case capitalCity = "capital_city"
case lat
case long
case updated
}
init(confirmed: Int?, recovered: Int?, deaths: Int?, country: String?, population: Int?,
squareKmArea: Int?, lifeExpectancy: String?, elevationInMeters: String?,
continent: String?, location: String?, iso: String?, capitalCity: String?,
lat: String?, long: String?, updated: String?) {
self.confirmed = confirmed
self.recovered = recovered
self.deaths = deaths
self.country = country
self.population = population
self.squareKmArea = squareKmArea
self.lifeExpectancy = lifeExpectancy
self.elevationInMeters = elevationInMeters
self.continent = continent
self.location = location
self.iso = iso
self.capitalCity = capitalCity
self.lat = lat
self.long = long
self.updated = updated
}
init(from decoder: Decoder) throws {
let container = try decoder.container(keyedBy: CodingKeys.self)
self.confirmed = try container.decodeIfPresent(Int.self, forKey: .confirmed)
self.recovered = try container.decodeIfPresent(Int.self, forKey: .recovered)
self.deaths = try container.decodeIfPresent(Int.self, forKey: .deaths)
self.country = try container.decodeIfPresent(String.self, forKey: .country)
self.population = try container.decodeIfPresent(Int.self, forKey: .population)
self.squareKmArea = try container.decodeIfPresent(Int.self, forKey: .squareKmArea)
self.lifeExpectancy = try container.decodeIfPresent(String.self, forKey: .lifeExpectancy)
self.elevationInMeters = try container.decodeIfPresent(String.self, forKey: .elevationInMeters)
self.continent = try container.decodeIfPresent(String.self, forKey: .continent)
self.location = try container.decodeIfPresent(String.self, forKey: .location)
self.iso = try container.decodeIfPresent(String.self, forKey: .iso)
self.capitalCity = try container.decodeIfPresent(String.self, forKey: .capitalCity)
self.lat = try container.decodeIfPresent(String.self, forKey: .lat)
self.long = try container.decodeIfPresent(String.self, forKey: .long)
self.updated = try container.decodeIfPresent(String.self, forKey: .updated)
do {
self.elevationInMeters = try String(container.decodeIfPresent(Int.self, forKey: .elevationInMeters) ?? 0)
} catch DecodingError.typeMismatch {
print("Not a number")
self.elevationInMeters = try container.decodeIfPresent(String.self, forKey: .elevationInMeters) ?? ""
}
}
}
The elevation in meters can come in either String or Int value (4+ digits long > String (appends a comma), otherwise Int) (Idea taken from this answer以米为单位的海拔可以采用字符串或整数值(4+ 位长 > 字符串(附加逗号),否则为整数)(取自此答案的想法
And I try to decode it this way我试着用这种方式解码
if let decodedData = self.jsonUtilities.decode(json: safeData, as: [String : Country].self) {
print(decodedData)
}
My above decode
method looks like this:我上面的decode
方法是这样的:
func decode<T: Decodable>(json: Data, as clazz: T.Type) -> T? {
do {
let decoder = JSONDecoder()
let data = try decoder.decode(T.self, from: json)
return data
} catch {
print(error)
print("An error occurred while parsing JSON")
}
return nil
}
I found this answer where they suggest adding all the Coding Keys there, but these are a ton.我在他们建议在那里添加所有编码键的地方找到了这个答案,但这些都很多。
I haven't added all the keys, as it's an 8k+ lines JSON, so I was wondering if there's an easier way to decode it, as I can't think of a better way to decode this JSON with unique keys.我没有添加所有的密钥,因为它是一个 8k+ 行 JSON,所以我想知道是否有更简单的方法来解码它,因为我想不出更好的方法来解码这个具有唯一密钥的 JSON。
Alternatively if I could ignore all the keys that aren't "All"
might also work, as I'm just trying to get the totals per country and their locations to place them in a map.或者,如果我可以忽略所有不是"All"
的键也可以工作,因为我只是想获得每个国家的总数及其位置,以将它们放在 map 中。
So far I get this error:到目前为止,我收到此错误:
typeMismatch(Swift.Dictionary<Swift.String, Any>, Swift.DecodingError.Context(codingPath: [_JSONKey(stringValue: "Diamond Princess", intValue: nil), CodingKeys(stringValue: "All", intValue: nil), _JSONKey(stringValue: "recovered", intValue: nil)], debugDescription: "Expected to decode Dictionary<String, Any> but found a number instead.", underlyingError: nil))
An error occurred while parsing JSON
And afaik it's because it's not finding the key "Diamond Princess" which is a state (or so I believe) in Canada (according to my JSON), because I haven't added it for the reasons above.而且afaik是因为它没有找到关键的“钻石公主”,它是加拿大的state(或者我相信)(根据我的JSON),因为我没有因为上述原因添加它。
When you have dynamic keys, you could decode it as [String: ...]
dictionary.当您有动态键时,您可以将其解码为[String: ...]
字典。
The structure of the JSON is as follows: JSON的结构如下:
{
"Canada": {
"All": { ... },
"Ontario": { ... },
...
},
"Mexico": { ... },
...
}
All the country stats have the key "All"
and if that's all you need then you could create the following structs:所有国家/地区的统计数据都有键"All"
,如果这就是您所需要的,那么您可以创建以下结构:
struct Country: Decodable {
var all: CountryAll
enum CodingKeys: String, CodingKey {
case all = "All"
}
}
struct CountryAll: Decodable {
var confirmed: Int
var recovered: Int
//.. etc
}
and decode as:并解码为:
let countries = try JSONDecoder().decode([String: Country].self, from: json)
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