无法通过 CustomCallAdapterFactory kotlin 通过改造调用从 LiveData 获取回调

Question

我是 MVVVM 的新手，我按照 Google 的 GihubBrowser 示例实施改造将 LiveData 回调，但我无法使用此实施对 rerofit 请求进行排队。请帮助我做错了什么：

存储库

class LoginRepository(var application: Application) {


    var result = MutableLiveData<Resource<GenericResponse>>()


    fun iniateOTPprocess()  {

        result = object : NetworkBoundResource<GenericResponse, GenericResponse>() {

            override fun createCall() = RetroUtils.getApiManager().listRepos()

            override fun processResponse(response: ApiSuccessResponse<GenericResponse>)
                    : GenericResponse {
                val body = response.body
                return body
            }
        }.asLiveData()
    }


    fun getData(): MutableLiveData<Resource<GenericResponse>> {
        return result
    }
}

视图模型

class LoginViewModel2(application: Application) : AndroidViewModel(application) {


    lateinit var username: MutableLiveData<String>
    lateinit var password: MutableLiveData<String>
    var repository: LoginRepository = LoginRepository(application)
    var data = MediatorLiveData<Resource<GenericResponse>>()


    init {
        data.addSource(repository.getData(), Observer {
            data.postValue(it)
        })
    }


    fun onLoginBtnCLicked() {
        initiateOTP()
    }


    private fun initiateOTP() {
        repository.iniateOTPprocess()
    }


    fun getResponse() : MutableLiveData<Resource<GenericResponse>>{
        return data
    }


}   

下面提到的是适配器

class LiveDataCallAdapter<R>(private val responseType: Type) :
    CallAdapter<R, LiveData<ApiResponse<R>>> {

    override fun responseType() = responseType

    override fun adapt(call: Call<R>): LiveData<ApiResponse<R>> {
        return object : LiveData<ApiResponse<R>>() {
            private var started = AtomicBoolean(false)
            override fun onActive() {
                super.onActive()
                if (started.compareAndSet(false, true)) {
                    call.enqueue(object : Callback<R> {
                        override fun onResponse(call: Call<R>, response: Response<R>) {
                            postValue(ApiResponse.create(response))
                        }

                        override fun onFailure(call: Call<R>, throwable: Throwable) {
                            postValue(ApiResponse.create(throwable))
                        }
                    })
                }
            }
        }
    }
}

活动

  class LoginActivity2 : AppCompatActivity() {


lateinit var binding: LoginViewBinding;
lateinit var vModel: LoginViewModel2;


override fun onCreate(savedInstanceState: Bundle?) {
    super.onCreate(savedInstanceState)
    binding = DataBindingUtil.setContentView(this, R.layout.login_view)
    binding.setLifecycleOwner(this)
    vModel = ViewModelProviders.of(this).get(LoginViewModel2::class.java)
    binding.loginViewModel = vModel



    vModel.getResponse().observe(this, Observer { t ->

        Log.e("data", t?.data.toString() ?: "Data is null")


    })

}


}

请注意这不是重复的

Retrofit LiveDataCallAdapter doesn't call function adapt (call)

如果我直接在 viewmodel 中直接观察 initialOTP() 方法，我可以使这段代码工作，但这样 API 将被命中，甚至无需点击我不想要的按钮。

请提出最佳方法。提前致谢。

Answer 1

每次调用iniateOTPprocess() 都会创建一个新的result，因此观察旧的没有用。试试这个：

存储库

class LoginRepository(var application: Application) {

    // remove this
    // var result = MutableLiveData<Resource<GenericResponse>>()

    fun initiateOtpProcess(): LiveData<Resource<GenericResponse>> {

        return object : NetworkBoundResource<GenericResponse, GenericResponse>() {

            override fun createCall() = RetroUtils.getApiManager().listRepos()

            override fun processResponse(response: ApiSuccessResponse<GenericResponse>)
                    : GenericResponse {
                val body = response.body
                return body
            }
        }.asLiveData()
    }

    // remove this as well
    // fun getData(): MutableLiveData<Resource<GenericResponse>>
}

在之前的Repository 设计中，initiateOTPprocess 和getData 必须按顺序调用。相反，让initiateOtpProcess 返回一个LiveData。

视图模型

class LoginViewModel2(application: Application) : AndroidViewModel(application) {

    lateinit var username: MutableLiveData<String>
    lateinit var password: MutableLiveData<String>
    val repository: LoginRepository = LoginRepository(application)
    val data = MediatorLiveData<Resource<GenericResponse>>()

    var currentOtpSource: LiveData<Resource<GenericResponse>>()


    // init {
    //    data.addSource(repository.getData(), Observer {
    //        data.postValue(it)
    //    })
    //}


    fun onLoginBtnCLicked() {
        initiateOTP()
    }


    private fun initiateOTP() {
        currentOtpSource?.let {
            // remove previous source if any
            data.removeSource(it)
        }

        newSource = repository.iniateOTPprocess()
        currentOtpSource = newSource

        data.addSource(newSource, Observer {
            data.setValue(it)
        })
    }


    fun getResponse() : LiveData<Resource<GenericResponse>>{
        return data
    }
}