组合执行嵌套请求

Question

我是Combine的新手，请帮忙。我需要组合 2 URL 个请求来接收完整的数据。第一个带有 id，第二个请求应该在他们的请求中使用这些 id。我需要它在一个出版商。所以我先表演：

func getDataFromServer(request: Request) -> AnyPublisher<MyData, NetworkError> {
    return networking.xml(request)
        .mapError { NetworkError.invalidData) }
        .flatMap { response -> AnyPublisher< MyData, NetworkError> in
            return Future< MyData, NetworkError>.init { promise in
                guard let data = MyData.from(response: response) else {
                    return promise(.failure(NetworkError.parseError))
                }
                if data.myID.count > 0 {
                    **// Perform second request with data.myID as parameter
                    // receive and fill additional fields data in 'data' object**
                }
                promise(.success(MyData))
            }.eraseToAnyPublisher()
        }
        .eraseToAnyPublisher()
}

Answer 1

删除 Future 只需提出其他请求 return AnyPublisher< MyData, NetworkError> 或根据您的响应类型更改该类型

func getDataFromServer(request: Request) -> AnyPublisher<MyData, NetworkError> {
    return networking.xml(request)
        .mapError { NetworkError.invalidData) }
        .flatMap { response -> AnyPublisher< MyData, NetworkError> in
            guard let data = MyData.from(response: response) else {
                return Fail(error: NetworkError.parseError).eraseToAnyPublisher()
            }
            
            if data.myID.count > 0 {
                // Perform second request with data.myID as parameter
                // receive and fill additional fields data in 'data' object
                return networking.makeYourRequest(with id: data.myID) // makeYourRequest method shoul return publisher with same type or possible to conver or change flatMap return type
            } else {
                return Just(data).eraseToAnyPublisher()
            }

        }
        .eraseToAnyPublisher()
}

组合执行嵌套请求

Combine perform nested requests

networking

ios

swift

combine