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问处理包含多个类型的JSON数组- Swift 4可解码
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Stack Overflow用户

提问于 2018-03-28 15:28:41

回答 3查看 7.1K关注 0票数 8

我正在尝试使用Swift 4代码来解析包含两种不同类型对象的数组。数据如下所示，included数组包含Member和ImageMedium对象：

{
  "data": [{
    "id": "8f7cbbac-c133-4b5e-a2ec-1f32353018fa",
    "type": "post",
    "title": "Test Post 1",
    "owner-id": "8986563c-438c-4d77-8115-9e5de2b6e477",
    "owner-type": "member"
  }, {
    "id": "f6b3c640-a58b-449f-93c7-f6cb7b569a9c",
    "type": "post",
    "title": "Test Post 2",
    "owner-id": "38d845a4-db66-48b9-9c15-d857166e255e",
    "owner-type": "member"
  }],
  "included": [{
    "id": "8986563c-438c-4d77-8115-9e5de2b6e477",
    "type": "member",
    "first-name": "John",
    "last-name": "Smith"
  }, {
    "id": "d7218ca1-de53-4832-bb8f-dbceb6747e98",
    "type": "image-medium",
    "asset-url": "https://faketest.com/fake-test-1.png",
    "owner-id": "f6b3c640-a58b-449f-93c7-f6cb7b569a9c",
    "owner-type": "post"
  }, {
    "id": "c59b8c72-13fc-44fd-8ef9-4b0f8fa486a0",
    "type": "image-medium",
    "asset-url": "https://faketest.com/fake-test-2.png",
    "owner-id": "8f7cbbac-c133-4b5e-a2ec-1f32353018fa",
    "owner-type": "post"
  }, {
    "id": "38d845a4-db66-48b9-9c15-d857166e255e",
    "type": "member",
    "first-name": "Jack",
    "last-name": "Doe"
  }]
}

我已经尝试了许多不同的方法来使用可解码来解决这个问题，但是到目前为止，唯一对我起作用的是为Included创建一个结构，它包含了两个对象的所有属性，如：

struct Root: Decodable {
    let data: [Post]?
    let included: [Included]?
}

struct Post: Decodable {
    let id: String?
    let type: String?
    let title: String?
    let ownerId: String?
    let ownerType: String?

    enum CodingKeys: String, CodingKey {
        case id
        case type
        case title
        case ownerId = "owner-id"
        case ownerType = "owner-type"
    }
}

struct Included: Decodable {
    let id: String?
    let type: String?
    let assetUrl: String?
    let ownerId: String?
    let ownerType: String?
    let firstName: String?
    let lastName: String?

    enum CodingKeys: String, CodingKey {
        case id
        case type
        case assetUrl = "asset-url"
        case ownerId = "owner-id"
        case ownerType = "owner-type"
        case firstName = "first-name"
        case lastName = "last-name"
    }
}

这可以通过实现一种方法来根据其Member属性从Included结构创建Included和ImageMedium对象，但是它显然不是理想的。我希望有一种使用自定义init(from decoder: Decoder)来完成这一任务的方法，但我还没有让它开始工作。有什么想法吗？

encodable

json

swift

swift4

decodable

回答 3

Stack Overflow用户

回答已采纳

发布于 2018-03-28 21:20:20

我想出了如何将混合的included数组解码成两个数组，每个数组都是一种类型。使用两个可解码的结构比使用一个结构来覆盖多种类型的数据更容易处理，也更通用。

对于任何感兴趣的人来说，这就是我的最终解决方案：

struct Root: Decodable {
    let data: [Post]?
    let members: [Member]
    let images: [ImageMedium]

    init(from decoder: Decoder) throws {

        let container = try decoder.container(keyedBy: CodingKeys.self)

        data = try container.decode([Post].self, forKey: .data)

        var includedArray = try container.nestedUnkeyedContainer(forKey: .included)
        var membersArray: [Member] = []
        var imagesArray: [ImageMedium] = []

        while !includedArray.isAtEnd {

            do {
                if let member = try? includedArray.decode(Member.self) {
                    membersArray.append(member)
                }
                else if let image = try? includedArray.decode(ImageMedium.self) {
                    imagesArray.append(image)
                }
            }
        }
        members = membersArray
        images = imagesArray
    }

    enum CodingKeys: String, CodingKey {
        case data
        case included
    }
}

struct Post: Decodable {
    let id: String?
    let type: String?
    let title: String?
    let ownerId: String?
    let ownerType: String?

    enum CodingKeys: String, CodingKey {
        case id
        case type
        case title
        case ownerId = "owner-id"
        case ownerType = "owner-type"
    }
}

struct Member: Decodable {
    let id: String?
    let type: String?
    let firstName: String?
    let lastName: String?

    enum CodingKeys: String, CodingKey {
        case id
        case type
        case firstName = "first-name"
        case lastName = "last-name"
    }
}

struct ImageMedium: Decodable {
    let id: String?
    let type: String?
    let assetUrl: String?
    let ownerId: String?
    let ownerType: String?

    enum CodingKeys: String, CodingKey {
        case id
        case type
        case assetUrl = "asset-url"
        case ownerId = "owner-id"
        case ownerType = "owner-type"
    }
}

票数 15

Stack Overflow用户

发布于 2018-03-28 16:08:02

这是基于初始编辑的，它有一些冗余代码，但是一般的想法应该是可以理解的：

enum Post: Codable {
    case post(id: UUID, title: String, ownerId: UUID, ownerType: PostOwner)
    case member(id: UUID, firstName: String, lastName: String)
    case imageMedium(id: UUID, assetURL: URL, ownerId: UUID, ownerType: ImageOwner)

    enum PostType: String, Codable {
        case post
        case member
        case imageMedium = "image-medium"
    }

    enum PostOwner: String, Codable {
        case member
    }

    enum ImageOwner: String, Codable {
        case post
    }

    enum CodingKeys: String, CodingKey {
        case id
        case type
        case title
        case assetUrl = "asset-url"
        case ownerId = "owner-id"
        case ownerType = "owner-type"
        case firstName = "first-name"
        case lastName = "last-name"
    }

    init(from decoder: Decoder) throws {
        let container = try decoder.container(keyedBy: CodingKeys.self)
        let id = try container.decode(UUID.self, forKey: .id)
        let type = try container.decode(PostType.self, forKey: .type)

        switch type {
        case .post:
            let title = try container.decode(String.self, forKey: .title)
            let ownerId = try container.decode(UUID.self, forKey: .ownerId)
            let ownerType = try container.decode(PostOwner.self, forKey: .ownerType)
            self = .post(id: id, title: title, ownerId: ownerId, ownerType: ownerType)
        case .member:
            let firstName = try container.decode(String.self, forKey: .firstName)
            let lastName = try container.decode(String.self, forKey: .lastName)
            self = .member(id: id, firstName: firstName, lastName: lastName)
        case .imageMedium:
            let assetURL = try container.decode(URL.self, forKey: .assetUrl)
            let ownerId = try container.decode(UUID.self, forKey: .ownerId)
            let ownerType = try container.decode(ImageOwner.self, forKey: .ownerType)
            self = .imageMedium(id: id, assetURL: assetURL, ownerId: ownerId, ownerType: ownerType)
        }
    }

    func encode(to encoder: Encoder) throws {
        var container = encoder.container(keyedBy: CodingKeys.self)
        switch self {
        case .post(let id, let title, let ownerId, let ownerType):
            try container.encode(PostType.post, forKey: .type)
            try container.encode(id, forKey: .id)
            try container.encode(title, forKey: .title)
            try container.encode(ownerId, forKey: .ownerId)
            try container.encode(ownerType, forKey: .ownerType)
        case .member(let id, let firstName, let lastName):
            try container.encode(PostType.member, forKey: .type)
            try container.encode(id, forKey: .id)
            try container.encode(firstName, forKey: .firstName)
            try container.encode(lastName, forKey: .lastName)
        case .imageMedium(let id, let assetURL, let ownerId, let ownerType):
            try container.encode(PostType.imageMedium, forKey: .type)
            try container.encode(id, forKey: .id)
            try container.encode(assetURL, forKey: .assetUrl)
            try container.encode(ownerId, forKey: .ownerId)
            try container.encode(ownerType, forKey: .ownerType)
        }
    }
}

let jsonDecoder = JSONDecoder()
let result = try jsonDecoder.decode([String: [Post]].self, from: yourJSONData)
print(result)

对于当前post类型中未使用的字段，它的选项为零，UUIDs被键入为UUID，URLs为URL，而不是到处都是String。

为了获得额外的类型安全性，ownerType被键入为PostOwner和ImageOwner表示.post和.imageMedium。

编辑：好，我检查了问题的编辑:在您的json中，只有“.post”进入"data"，而rest进入"included“。在我的答案中，Posts和Includeds合并成一种类型。

所以应该是这样的：

struct Post: Codable {
    let id: UUID
    let title: String
    let ownerId: UUID
    let ownerType: PostOwner

    enum PostOwner: String, Codable {
        case member
    }

    enum CodingKeys: String, CodingKey {
        case id
        case title
        case ownerId = "owner-id"
        case ownerType = "owner-type"
    }
}

enum Included: Codable {
    case member(id: UUID, firstName: String, lastName: String)
    case imageMedium(id: UUID, assetURL: URL, ownerId: UUID, ownerType: ImageOwner)

    enum PostType: String, Codable {
        case member
        case imageMedium = "image-medium"
    }

    enum ImageOwner: String, Codable {
        case post
    }

    enum CodingKeys: String, CodingKey {
        case id
        case type
        case title
        case assetUrl = "asset-url"
        case ownerId = "owner-id"
        case ownerType = "owner-type"
        case firstName = "first-name"
        case lastName = "last-name"
    }

    init(from decoder: Decoder) throws {
        let container = try decoder.container(keyedBy: CodingKeys.self)
        let id = try container.decode(UUID.self, forKey: .id)
        let type = try container.decode(PostType.self, forKey: .type)

        switch type {
        case .member:
            let firstName = try container.decode(String.self, forKey: .firstName)
            let lastName = try container.decode(String.self, forKey: .lastName)
            self = .member(id: id, firstName: firstName, lastName: lastName)
        case .imageMedium:
            let assetURL = try container.decode(URL.self, forKey: .assetUrl)
            let ownerId = try container.decode(UUID.self, forKey: .ownerId)
            let ownerType = try container.decode(ImageOwner.self, forKey: .ownerType)
            self = .imageMedium(id: id, assetURL: assetURL, ownerId: ownerId, ownerType: ownerType)
        }
    }

    func encode(to encoder: Encoder) throws {
        var container = encoder.container(keyedBy: CodingKeys.self)
        switch self {
        case .member(let id, let firstName, let lastName):
            try container.encode(PostType.member, forKey: .type)
            try container.encode(id, forKey: .id)
            try container.encode(firstName, forKey: .firstName)
            try container.encode(lastName, forKey: .lastName)
        case .imageMedium(let id, let assetURL, let ownerId, let ownerType):
            try container.encode(PostType.imageMedium, forKey: .type)
            try container.encode(id, forKey: .id)
            try container.encode(assetURL, forKey: .assetUrl)
            try container.encode(ownerId, forKey: .ownerId)
            try container.encode(ownerType, forKey: .ownerType)
        }
    }
}

Post类型解析/验证可以/应该通过手动编码init(from: )来添加。

票数 2

Stack Overflow用户

发布于 2018-03-28 15:59:14

我的建议是对所有项目使用单一类型的Post。要区分不同的类型，可以将type密钥解码为枚举，并根据情况对属性进行解码。

这需要将所有非全局属性声明为var。

struct Root : Decodable {
    let data : [Post]
    let included : [Post]
}

enum PostType : String, Decodable {
    case member, post, imageMedium = "image-medium"
}

struct Post : Decodable {
    let id: String
    let type: PostType

    var title: String?
    var assetUrl: String?
    var ownerId: String?
    var ownerType: String?
    var firstName: String?
    var lastName: String?

    enum CodingKeys: String, CodingKey {
        case id, type, title
        case assetUrl = "asset-url"
        case ownerId = "owner-id"
        case ownerType = "owner-type"
        case firstName = "first-name"
        case lastName = "last-name"
    }

    init(from decoder: Decoder) throws {
        let container = try decoder.container(keyedBy: CodingKeys.self)
        id = try container.decode(String.self, forKey: .id)
        type = try container.decode(PostType.self, forKey: .type)
        switch type {
        case .member:
            firstName = try container.decode(String.self, forKey: .firstName)
            lastName = try container.decode(String.self, forKey: .lastName)
        case .post:
            title = try container.decode(String.self, forKey: .title)
            ownerId = try container.decode(String.self, forKey: .ownerId)
            ownerType = try container.decode(String.self, forKey: .ownerType)
        case .imageMedium:
            assetUrl = try container.decode(String.self, forKey: .assetUrl)
            ownerId = try container.decode(String.self, forKey: .ownerId)
            ownerType = try container.decode(String.self, forKey: .ownerType)
        }
    }
}

票数 0

页面原文内容由Stack Overflow提供。腾讯云小微IT领域专用引擎提供翻译支持

原文链接：

https://stackoverflow.com/questions/49538509

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