我试图在swift 4中解析可解码的json数据。它显示nil值。我找不到这是什么问题？
这是模型类：
choseCard(card) => {
const {playCard, player1} = this.state;
return this.setState({
playCard: playCard.concat(card),
player1: player1.filter(c => c.id !== card.id)
});
}
这是json：
public struct TaskID: Decodable {
let embedded: Embedded?
let count: Int?
enum CodingKeys: String, CodingKey {
case count = "count"
case embedded = "_embedded"
}
}
public struct Embedded: Decodable {
let task: [Task]?
enum CodingKeys: String, CodingKey {
case task = "task"
}
}
public struct Task : Decodable {
let id : String?
let name: String?
let assignee: String?
let created: String?
let processDefinitionId: String?
enum CodingKeys: String, CodingKey {
case id = "id"
case name = "name"
case assignee = "assignee"
case created = "created"
case processDefinitionId = "processDefinitionId"
}
}
这里是urlrequest：
{
"_links": {
"self": {
"href": "/task"
}
},
"_embedded": {
"task": [
{
"_links": {
"assignee": {
"href": "/user/demo"
},
"execution": {
"href": "/execution/1b64cf75-0616-11ea-8860-120ef5ab2c25"
},
"identityLink": {
"href": "/task/1b64f688-0616-11ea-8860-120ef5ab2c25/identity-links"
},
"processDefinition": {
"href": "/process-definition/quickEvaluation:1:129ce2b1-0616-11ea-8860-120ef5ab2c25"
},
"processInstance": {
"href": "/process-instance/1b64cf75-0616-11ea-8860-120ef5ab2c25"
},
"self": {
"href": "/task/1b64f688-0616-11ea-8860-120ef5ab2c25"
}
},
"_embedded": {
"variable": []
},
"id": "1b64f688-0616-11ea-8860-120ef5ab2c25",
"name": "Quick Evaluation",
"assignee": "demo",
"created": "2019-11-13T13:04:20.687+0000",
"due": null,
"followUp": null,
"delegationState": null,
"description": null,
"executionId": "1b64cf75-0616-11ea-8860-120ef5ab2c25",
"owner": null,
"parentTaskId": null,
"priority": 50,
"processDefinitionId": "quickEvaluation:1:129ce2b1-0616-11ea-8860-120ef5ab2c25",
"processInstanceId": "1b64cf75-0616-11ea-8860-120ef5ab2c25",
"taskDefinitionKey": "QuickEvaluation",
"caseExecutionId": null,
"caseInstanceId": null,
"caseDefinitionId": null,
"suspended": false,
"formKey": "a8apps:suryoday:gng:v0.1.0:kycUpload",
"tenantId": null
},
{
"_links": {
"assignee": {
"href": "/user/demo"
},
"execution": {
"href": "/execution/412a03b7-06ae-11ea-8860-120ef5ab2c25"
},
"identityLink": {
"href": "/task/412a2aca-06ae-11ea-8860-120ef5ab2c25/identity-links"
},
"processDefinition": {
"href": "/process-definition/quickEvaluation:1:129ce2b1-0616-11ea-8860-120ef5ab2c25"
},
"processInstance": {
"href": "/process-instance/412a03b7-06ae-11ea-8860-120ef5ab2c25"
},
"self": {
"href": "/task/412a2aca-06ae-11ea-8860-120ef5ab2c25"
}
},
"_embedded": {
"variable": [
{
"_links": {
"self": {
"href": "/process-instance/412a03b7-06ae-11ea-8860-120ef5ab2c25/variables/loanAmount"
}
},
"_embedded": null,
"name": "loanAmount",
"value": "650000",
"type": "String",
"valueInfo": {}
},
{
"_links": {
"self": {
"href": "/process-instance/412a03b7-06ae-11ea-8860-120ef5ab2c25/variables/firstName"
}
},
"_embedded": null,
"name": "firstName",
"value": "Kamesh",
"type": "String",
"valueInfo": {}
}
]
},
"id": "412a2aca-06ae-11ea-8860-120ef5ab2c25",
"name": "Quick Evaluation",
"assignee": "demo",
"created": "2019-11-14T07:13:27.558+0000",
"due": null,
"followUp": null,
"delegationState": null,
"description": null,
"executionId": "412a03b7-06ae-11ea-8860-120ef5ab2c25",
"owner": null,
"parentTaskId": null,
"priority": 50,
"processDefinitionId": "quickEvaluation:1:129ce2b1-0616-11ea-8860-120ef5ab2c25",
"processInstanceId": "412a03b7-06ae-11ea-8860-120ef5ab2c25",
"taskDefinitionKey": "QuickEvaluation",
"caseExecutionId": null,
"caseInstanceId": null,
"caseDefinitionId": null,
"suspended": false,
"formKey": "a8apps:suryoday:gng:v0.1.0:kycUpload",
"tenantId": null
}
]
},
"count": 13
}
以下是alamofire请求：
// MARK: - URLRequestConvertible
func asURLRequest() throws -> URLRequest {
let url = try K.ProductionServer.baseURL.asURL()
var urlRequest = URLRequest(url: url.appendingPathComponent(path))
print(urlRequest)
// HTTP Method
urlRequest.httpMethod = method.rawValue
let authToken = UserDefaults.standard.string(forKey: "authToken")
let bearerToken: String = "Bearer " + (authToken ?? "")
print("baearer token::\(bearerToken)")
// Common Headers
urlRequest.setValue(ContentType.json.rawValue, forHTTPHeaderField: HTTPHeaderField.acceptType.rawValue)
urlRequest.setValue(ContentType.json.rawValue, forHTTPHeaderField: HTTPHeaderField.contentType.rawValue)
urlRequest.setValue(bearerToken, forHTTPHeaderField: HTTPHeaderField.authentication.rawValue)
// Parameters
if let parameters = parameters {
do {
urlRequest.httpBody = try JSONSerialization.data(withJSONObject: parameters, options: [])
} catch {
throw AFError.parameterEncodingFailed(reason: .jsonEncodingFailed(error: error))
}
}
return urlRequest
}
最初显示的是字典，Swift.DecodingError.Context（codingPath：[]，debugDescription：“预期用于解码Dictionary，但找到一个数组。，但是现在我在控制台日志中显示为nil。不知道为什么我得到nil值。根据我的json响应struct是否正确？我正在努力获取嵌套数据。
任何帮助，不胜感激。
答案 0 :(得分：1)
您的结构正确。请参见下面的游乐场以获取证明；我没有错。如果您没有完整的数据集，并且假设响应中的某些可选字段是非可选的，则nil是非常常见的结果，因为您在示例数据中看到了该字段（您的示例不一定具有代表性）。如果没有服务器的实际规格，则需要确定哪个字段解码失败，并且可能需要获取一堆数据才能确定哪些字段真正是可选的。您可以通过在上面的AF项目中放入错误处理代码，或仅将响应粘贴到下面的我的游乐场中来实现。无论哪种方式，解码错误都可以告诉您不存在哪个字段。
import PlaygroundSupport
import UIKit
import WebKit
public struct TaskID: Decodable {
let embedded: Embedded?
let count: Int?
enum CodingKeys: String, CodingKey {
case count = "count"
case embedded = "_embedded"
}
}
public struct Embedded: Decodable {
let task: [Task]?
enum CodingKeys: String, CodingKey {
case task = "task"
}
}
public struct Task : Decodable {
let id : String?
let name: String?
let assignee: String?
let created: String?
let processDefinitionId: String?
enum CodingKeys: String, CodingKey {
case id = "id"
case name = "name"
case assignee = "assignee"
case created = "created"
case processDefinitionId = "processDefinitionId"
}
}
let data = """
{
"_links": {
"self": {
"href": "/task"
}
},
"_embedded": {
"task": [
{
"_links": {
"assignee": {
"href": "/user/demo"
},
"execution": {
"href": "/execution/1b64cf75-0616-11ea-8860-120ef5ab2c25"
},
"identityLink": {
"href": "/task/1b64f688-0616-11ea-8860-120ef5ab2c25/identity-links"
},
"processDefinition": {
"href": "/process-definition/quickEvaluation:1:129ce2b1-0616-11ea-8860-120ef5ab2c25"
},
"processInstance": {
"href": "/process-instance/1b64cf75-0616-11ea-8860-120ef5ab2c25"
},
"self": {
"href": "/task/1b64f688-0616-11ea-8860-120ef5ab2c25"
}
},
"_embedded": {
"variable": []
},
"id": "1b64f688-0616-11ea-8860-120ef5ab2c25",
"name": "Quick Evaluation",
"assignee": "demo",
"created": "2019-11-13T13:04:20.687+0000",
"due": null,
"followUp": null,
"delegationState": null,
"description": null,
"executionId": "1b64cf75-0616-11ea-8860-120ef5ab2c25",
"owner": null,
"parentTaskId": null,
"priority": 50,
"processDefinitionId": "quickEvaluation:1:129ce2b1-0616-11ea-8860-120ef5ab2c25",
"processInstanceId": "1b64cf75-0616-11ea-8860-120ef5ab2c25",
"taskDefinitionKey": "QuickEvaluation",
"caseExecutionId": null,
"caseInstanceId": null,
"caseDefinitionId": null,
"suspended": false,
"formKey": "a8apps:suryoday:gng:v0.1.0:kycUpload",
"tenantId": null
},
{
"_links": {
"assignee": {
"href": "/user/demo"
},
"execution": {
"href": "/execution/412a03b7-06ae-11ea-8860-120ef5ab2c25"
},
"identityLink": {
"href": "/task/412a2aca-06ae-11ea-8860-120ef5ab2c25/identity-links"
},
"processDefinition": {
"href": "/process-definition/quickEvaluation:1:129ce2b1-0616-11ea-8860-120ef5ab2c25"
},
"processInstance": {
"href": "/process-instance/412a03b7-06ae-11ea-8860-120ef5ab2c25"
},
"self": {
"href": "/task/412a2aca-06ae-11ea-8860-120ef5ab2c25"
}
},
"_embedded": {
"variable": [
{
"_links": {
"self": {
"href": "/process-instance/412a03b7-06ae-11ea-8860-120ef5ab2c25/variables/loanAmount"
}
},
"_embedded": null,
"name": "loanAmount",
"value": "650000",
"type": "String",
"valueInfo": {}
},
{
"_links": {
"self": {
"href": "/process-instance/412a03b7-06ae-11ea-8860-120ef5ab2c25/variables/firstName"
}
},
"_embedded": null,
"name": "firstName",
"value": "Kamesh",
"type": "String",
"valueInfo": {}
}
]
},
"id": "412a2aca-06ae-11ea-8860-120ef5ab2c25",
"name": "Quick Evaluation",
"assignee": "demo",
"created": "2019-11-14T07:13:27.558+0000",
"due": null,
"followUp": null,
"delegationState": null,
"description": null,
"executionId": "412a03b7-06ae-11ea-8860-120ef5ab2c25",
"owner": null,
"parentTaskId": null,
"priority": 50,
"processDefinitionId": "quickEvaluation:1:129ce2b1-0616-11ea-8860-120ef5ab2c25",
"processInstanceId": "412a03b7-06ae-11ea-8860-120ef5ab2c25",
"taskDefinitionKey": "QuickEvaluation",
"caseExecutionId": null,
"caseInstanceId": null,
"caseDefinitionId": null,
"suspended": false,
"formKey": "a8apps:suryoday:gng:v0.1.0:kycUpload",
"tenantId": null
}
]
},
"count": 13
}
""".data(using: .utf8)!
let decoder = JSONDecoder()
do {
let decoded = try decoder.decode(TaskID.self, from: data)
print(decoded)
} catch ( let error ) {
print(error.localizedDescription)
}
答案 1 :(得分：0)
import Foundation
// MARK: - Task
struct Task: Codable {
let links: VariableLinks?
let embedded: TaskEmbedded?
let count: Int?
enum CodingKeys: String, CodingKey {
case links = "_links"
case embedded = "_embedded"
case count = "count"
}
}
// MARK: - TaskEmbedded
struct TaskEmbedded: Codable {
let task: [TaskElement]?
enum CodingKeys: String, CodingKey {
case task = "task"
}
}
// MARK: - TaskElement
struct TaskElement: Codable {
let links: TaskLinks?
let embedded: TaskEmbeddedClass?
let id: String?
let name: String?
let assignee: String?
let created: String?
let due: String?
let followUp: String?
let delegationState: String?
let taskDescription: String?
let executionId: String?
let owner: String?
let parentTaskId: Int?
let priority: Int?
let processDefinitionId: String?
let processInstanceId: String?
let taskDefinitionKey: String?
let caseExecutionId: Int?
let caseInstanceId: Int?
let caseDefinitionId: Int?
let suspended: Bool?
let formKey: String?
let tenantId: Int?
enum CodingKeys: String, CodingKey {
case links = "_links"
case embedded = "_embedded"
case id = "id"
case name = "name"
case assignee = "assignee"
case created = "created"
case due = "due"
case followUp = "followUp"
case delegationState = "delegationState"
case taskDescription = "description"
case executionId = "executionId"
case owner = "owner"
case parentTaskId = "parentTaskId"
case priority = "priority"
case processDefinitionId = "processDefinitionId"
case processInstanceId = "processInstanceId"
case taskDefinitionKey = "taskDefinitionKey"
case caseExecutionId = "caseExecutionId"
case caseInstanceId = "caseInstanceId"
case caseDefinitionId = "caseDefinitionId"
case suspended = "suspended"
case formKey = "formKey"
case tenantId = "tenantId"
}
}
// MARK: - TaskEmbeddedClass
struct TaskEmbeddedClass: Codable {
let variable: [Variable]?
enum CodingKeys: String, CodingKey {
case variable = "variable"
}
}
// MARK: - Variable
struct Variable: Codable {
let links: VariableLinks?
let embedded: String?
let name: String?
let value: String?
let type: String?
let valueInfo: ValueInfo?
enum CodingKeys: String, CodingKey {
case links = "_links"
case embedded = "_embedded"
case name = "name"
case value = "value"
case type = "type"
case valueInfo = "valueInfo"
}
}
// MARK: - VariableLinks
struct VariableLinks: Codable {
let linksSelf: SelfClass?
enum CodingKeys: String, CodingKey {
case linksSelf = "self"
}
}
// MARK: - SelfClass
struct SelfClass: Codable {
let href: String?
enum CodingKeys: String, CodingKey {
case href = "href"
}
}
// MARK: - ValueInfo
struct ValueInfo: Codable {
}
// MARK: - TaskLinks
struct TaskLinks: Codable {
let assignee: SelfClass?
let execution: SelfClass?
let identityLink: SelfClass?
let processDefinition: SelfClass?
let processInstance: SelfClass?
let linksSelf: SelfClass?
enum CodingKeys: String, CodingKey {
case assignee = "assignee"
case execution = "execution"
case identityLink = "identityLink"
case processDefinition = "processDefinition"
case processInstance = "processInstance"
case linksSelf = "self"
}
}
此外，如果您感到懒惰，可以使用quicktype.io，因为nil是可解码的非常常见的响应，因此您可以扩展DataRequest来解析并从请求中获取值，就像使用responseDecodable，在这里您可以使用类似的内容
extension DataRequest {
fileprivate func decodableResponseSerializer<T: Decodable>() -> DataResponseSerializer<T> {
return DataResponseSerializer { _, response, data, error in
guard error == nil else { return .failure(error!) }
guard let data = data else {
return .failure(AFError.responseSerializationFailed(reason: .inputDataNil))
}
return Result { try newJSONDecoder().decode(T.self, from: data) }
}
}
@discardableResult
fileprivate func responseDecodable<T: Decodable>(queue: DispatchQueue? = nil, completionHandler: @escaping (DataResponse<T>) -> Void) -> Self {
return response(queue: queue, responseSerializer: decodableResponseSerializer(), completionHandler: completionHandler)
}
}
然后您可以这样称呼
Alamofire.request(url, method:.post, parameters: parameters, headers: headers)
.responseDecodable { (response: DataResponse< Task >) in completion(response.result) }
当您得到这样的信息时，它仅在您具有不同类型的数据而不是您指定的数据时出现。