RxSwift - 递归 Observables？

Posted 2023-03-10

【中文标题】RxSwift - 递归 Observables？

【英文标题】：RxSwift - Recursive Observables?

【发布时间】：2019-08-19 11:23:48

【问题描述】：

学习 RxSwift - 这是我的问题：

我有一个使用活动访问令牌获取数据的网络服务，每当令牌过期时，首先调用令牌生成 api，然后调用当前请求再次运行。这样它就会有一个有效的访问令牌来访问有效的结果。

但我在获取令牌响应然后调用上一个时遇到问题。请求？

所以我尝试添加一个 observable 请求，然后作为响应检查令牌是否无效，然后调用另一个 observable 以返回一个活动令牌，一旦收到令牌，再次调用旧请求。

func apirequest(_ urlConvertible:URLRequestConvertible) -> Observable<[String:AnyObject]> 
  return Observable.create( observer  -> Disposable in
         let _ = Alamofire.request(urlConvertible).responseJSON  
                       response in 
         if isTokenExpired() 
             self.generateToken().subscribe(onNext: response 
               self.apirequest(oldRequest)
          )
        
      
      return Disposables.create()
   )

我期待任何 Rx 操作员或任何想法尝试？

谢谢

【参考方案1】：

我写了一篇关于如何做到这一点的文章：https://medium.com/@danielt1263/retrying-a-network-request-despite-having-an-invalid-token-b8b89340d29

将您的网络调用代码包装成这样：

/// Builds and makes network requests using the token provided by the service. Will request a new token and retry if the result is an unauthorized (401) error.
///
/// - Parameters:
///   - response: A function that sends requests to the network and emits responses. Can be for example `URLSession.shared.rx.response`
///   - tokenAcquisitionService: The object responsible for tracking the auth token. All requests should use the same object.
///   - request: A function that can build the request when given a token.
///   - Returns: response of a guaranteed authorized network request.
public func getData<T>(response: @escaping (URLRequest) -> Observable<(response: HTTPURLResponse, data: Data)>, tokenAcquisitionService: TokenAcquisitionService<T>, request: @escaping (T) throws -> URLRequest) -> Observable<(response: HTTPURLResponse, data: Data)> 
return Observable
        .deferred  tokenAcquisitionService.token.take(1) 
        .map  try request($0) 
        .flatMap  response($0) 
        .map  response in
            guard response.response.statusCode != 401 else  throw TokenAcquisitionError.unauthorized 
            return response
        
        .retryWhen  $0.renewToken(with: tokenAcquisitionService) 

文章和随附的要点展示了如何编写 tokenAcquisitionService 并包含单元测试。

【讨论】：

谢谢丹尼尔 - 会看看。