Swift可解码日期为空字符串或零

Question

情况

我正在处理一个API服务器，它有多个日期字段，我已经看到这些日期字段的API响应可以是：

{
"clicktimestamp": "",
"clicktimestamp": "  ",  
"clicktimestamp": "2020-08-08 16:13:17"
}

JSON响应可以是：
•字符串(无空格(
·字符串(带空格(
•具有某种日期格式的字符串。

我没有访问API服务器，我不能要求服务器端工程师更改它。我的情况不理想，所以我必须处理它。

工作解决方案(不是很快(

我写了一些代码来处理这种情况。它很有效，但有些地方感觉不太Swift。

考虑到我的JSON响应情况，我如何改进整个解码过程
还是它很好？

这是一个有效的解决方案：

import UIKit
import Foundation
struct ProductDate: Decodable, Hashable {
var lastcheckedtime: Date?
var oktime: Date?
var clicktimestamp: Date?
var lastlocaltime: Date?
// I have more properties but I'm omitting them
}
extension ProductDate {

private enum Keys: String, CodingKey {
case lastcheckedtime
case oktime
case clicktimestamp
case lastlocaltime
}

init(from decoder: Decoder) throws {

let formatter = DateFormatter.yyyyMMdd
let container = try decoder.container(keyedBy: Keys.self)

let dateKeys: [KeyedDecodingContainer<Keys>.Key] = [
.lastcheckedtime,
.oktime,
.clicktimestamp,
.lastlocaltime
]
let parseDate: (String, KeyedDecodingContainer<Keys>.Key, KeyedDecodingContainer<Keys>) throws -> Date? = {(dateString, someKey, container) in
if !dateString.isEmpty {
if let date = formatter.date(from: dateString) {
return date
} else {
throw DecodingError.dataCorruptedError(forKey: someKey,
in: container,
debugDescription: "Date string does not match format expected by formatter.")
}
} else {
return nil
}
}
let datesResults: [Date?] = try dateKeys.map({ key in
// 1.  decode as a string because we sometimes get "" or  " " for those date fields as the API server is poorly managed.
let dateString = try container.decode(String.self, forKey: key)
.trimmingCharacters(in: .whitespaces)
// 2. now pass in our dateString which could be "" or " " or "2020-08-08 16:13:17"
// and try to parse it into a Date or nil
let result = try parseDate(dateString, key, container)
return result
})
// 3. Assign our array of dateResults to our struct keys
lastcheckedtime = datesResults[0]
oktime          = datesResults[1]
clicktimestamp  = datesResults[2]
lastlocaltime   = datesResults[3]


}

}

extension DateFormatter {
static let yyyyMMdd: DateFormatter = {
let formatter = DateFormatter()
formatter.dateFormat = "YYYY-MM-DD HH:mm:ss"
formatter.calendar = Calendar(identifier: .iso8601)
formatter.timeZone = TimeZone(secondsFromGMT: 0)
formatter.locale = Locale(identifier: "en_US_POSIX")
return formatter
}()
}

let json = """
{
"lastcheckedtime": "",
"oktime": " ",
"clicktimestamp": "",
"lastlocaltime": "2020-08-08 16:13:17"
}
""".data(using: .utf8)!

let decoder = JSONDecoder()

print(json)
do {
let decoded = try decoder.decode(ProductDate.self, from: json)
print(decoded)
} catch let context {
print(context)
}

Answer 1

太复杂了。

添加一个dateDecodingStrategy并解码Date。如果失败，则分配nil。

不需要修剪的东西。

还要注意，您的日期格式是错误的。

struct ProductDate: Decodable, Hashable {
var lastcheckedtime: Date?
var oktime: Date?
var clicktimestamp: Date?
var lastlocaltime: Date?
}
extension ProductDate {

private enum CodingKeys: String, CodingKey {
case lastcheckedtime, oktime, clicktimestamp, lastlocaltime
}

init(from decoder: Decoder) throws {
let container = try decoder.container(keyedBy: CodingKeys.self)
lastcheckedtime = try? container.decode(Date.self, forKey: .lastcheckedtime)
oktime = try? container.decode(Date.self, forKey: .oktime)
clicktimestamp = try? container.decode(Date.self, forKey: .clicktimestamp)
lastlocaltime = try? container.decode(Date.self, forKey: .lastlocaltime)
}
}

extension DateFormatter {
static let yyyyMMdd: DateFormatter = {
let formatter = DateFormatter()
formatter.locale = Locale(identifier: "en_US_POSIX")
formatter.dateFormat = "yyyy-MM-dd HH:mm:ss"
formatter.timeZone = TimeZone(secondsFromGMT: 0)
return formatter
}()
}

let json = """
{
"lastcheckedtime": "",
"oktime": " ",
"clicktimestamp": "",
"lastlocaltime": "2020-08-08 16:13:17"
}
"""

let decoder = JSONDecoder()
decoder.dateDecodingStrategy = .formatted(.yyyyMMdd)

print(json)
do {
let decoded = try decoder.decode(ProductDate.self, from: Data(json.utf8))
print(decoded)
} catch let context {
print(context)
}

Answer 2

我会使用dateDecodingStrategy为解码器设置一个自定义日期格式化程序，如

let decoder = JSONDecoder()
decoder.dateDecodingStrategy = .formatted(DateFormatter.yyyyMMdd)

然后在自定义init中，我将首先解码为字符串，并检查它是否为空，如果不是，则解码为日期(使用上面的格式化程序(

init(from decoder: Decoder) throws {
let container = try decoder.container(keyedBy: Keys.self)
if try !container.decode(String.self, forKey: .lastcheckedtime).trimmingCharacters(in: .whitespaces).isEmpty {
lastcheckedtime = try container.decode(Date.self, forKey: .lastcheckedtime)
}
if try !container.decode(String.self, forKey: .oktime).trimmingCharacters(in: .whitespaces).isEmpty {
oktime = try container.decode(Date.self, forKey: .oktime)
}
if try !container.decode(String.self, forKey: .clicktimestamp).trimmingCharacters(in: .whitespaces).isEmpty {
clicktimestamp = try container.decode(Date.self, forKey: .clicktimestamp)
}
if try !container.decode(String.self, forKey: .lastlocaltime).trimmingCharacters(in: .whitespaces).isEmpty {
lastlocaltime = try container.decode(Date.self, forKey: .lastlocaltime)
}
}