如何使用Codable解析SubReddits JSON

Question

我使用的URL是“ https://www.reddit.com/subreddits/.json”，它将为您提供Reddit的Subreddits的JSON格式。

我的可编码结构模型如下：

struct SubredditsData: Codable {
    let data: SubredditData
}

struct SubredditData: Codable {
    let children: [Children]
}

struct Children: Codable {
    let data: ChildrenData
}

struct ChildrenData: Codable {
    let title: String
    let icon_img: String
    let display_name_prefixed: String
    let name: String
}

当然还有Subreddit的模型

struct SubredditsModel {
    let title: String
    let display_name_prefixed: String
    let name: String
}

然后我执行了一个请求并进行了实际的解析

func parseSubRedditsJSON(_ subredditsRawData: Data) -> [SubredditsModel]? {
    let decoder = JSONDecoder()
    do {
        var subReddits = [SubredditsModel]()
        let decodedData = try decoder.decode(SubredditsData.self, from: subredditsRawData)
        let data = decodedData.data
        let children = data.children
        for item in children {
            let childrenData = item.data
            let title = childrenData.title
            let display_name_prefixed = childrenData.display_name_prefixed
            let name = childrenData.name
            let subReddit = SubredditsModel(title: title, display_name_prefixed: display_name_prefixed, name: name)
            subReddits.append(subReddit)
        }
        return subReddits
    } catch {
        subredditsDelegate?.didFailWithError(error: error)
        return nil
    }
}//end of parseSubRedditsJSON

我正在通过协议委托从请求管理器将数据返回到视图控制器，这很好用。问题是我在此行出现错误

let decodedData = try decoder.decode(SubredditsData.self, from: subredditsRawData)

错误说：

valueNotFound(Swift.String, Swift.DecodingError.Context(codingPath: [CodingKeys(stringValue: "data", intValue: nil), 
CodingKeys(stringValue: "children", intValue: nil), _JSONKey(stringValue: "Index 5", intValue: 5), 
CodingKeys(stringValue: "data", intValue: nil), 
CodingKeys(stringValue: "icon_img", intValue: nil)], 
debugDescription: "Expected String value but found null instead.", underlyingError: nil))

我必须缺少某些东西，或者没有使用Swift编码实现正确的解析方式。

Answer 1

确定，所以解析方法毕竟是正确的。我只是错过了let icon_img：可以为空的字符串。

Answer 2

由于某些字段不是可选的，因此可能需要字符串类型或null，使其成为可选将解决此问题。

struct SubredditsData: Codable {
    let data: SubredditData
 }

 struct SubredditData: Codable {
    let children: [Children]
 }

 struct Children: Codable {
   let data: ChildrenData
 }

 struct ChildrenData: Codable {
   let title: String?
   let icon_img: String?
   let display_name_prefixed: String?
   let name: String?
 }