Question

我已经创建了一个抽象的BaseFragment类，它将由其他具体的Fragment类进行扩展。我想使用ViewModel在我的BaseFragment中注入Koin。这是我的BaseFragment：

abstract class BaseFragment<out VM : BaseViewModel, DB : ViewDataBinding>(private val mViewModelClass: Class<VM>) : Fragment() {

    val viewModel: VM by viewModel()

    open lateinit var binding: DB

    fun init(inflater: LayoutInflater, container: ViewGroup) {
        binding = DataBindingUtil.inflate(inflater, getLayoutRes(), container, false)
    }

    open fun init() {}
    @LayoutRes
    abstract fun getLayoutRes(): Int

    override fun onCreateView(inflater: LayoutInflater, container: ViewGroup?,
                              savedInstanceState: Bundle?): View {
        init(inflater, container!!)
        init()
        super.onCreateView(inflater, container, savedInstanceState)
        return binding.root
    }

    open fun refresh() {}
}

但是我不能这样做。我正在使用2.0.1版的Koin。

Answer 1

我的情况也一样。您也可以像下面这样：

添加ViewModel作为摘要，并在扩展BaseFragment时设置值。

我的 BaseFragment 有：

abstract class BaseFragment<Binding : ViewDataBinding, ViewModel : BaseViewModel> : Fragment() {
    protected abstract val mViewModel: ViewModel
    protected lateinit var bindingObject: Binding

    override fun onCreateView(inflater: LayoutInflater, container: ViewGroup?, savedInstanceState: Bundle?): View? {
        bindingObject = DataBindingUtil.inflate(inflater, getLayoutResId(), container, false)
        return bindingObject.root
    }

     /**
       * Get layout resource id which inflate in onCreateView.
      */
     @LayoutRes
     abstract fun getLayoutResId(): Int

     override fun onViewCreated(view: View, savedInstanceState: Bundle?) {
        super.onViewCreated(view, savedInstanceState)
        doDataBinding()
    }

     /**
      * Do your other stuff in init after binding layout.
      */
      abstract fun init()

     private fun doDataBinding() {
       bindingObject.lifecycleOwner = viewLifecycleOwner // it is extra if you want to set life cycle owner in binding
       // Here your viewModel and binding variable imlementation 
       bindingObject.setVariable(BR.viewModel, mViewModel)  // In all layout the variable name should be "viewModel"
       bindingObject.executePendingBindings()
       init()
}

}

这是我实际的Fragment实现：

class FragmentComments : BaseFragment<FragmentCommentsBinding, FragmentCommentsVM>() {
// Here is the your viewmodel imlementation 
override val mViewModel: FragmentCommentsVM by viewModel() 

override fun getLayoutResId(): Int = [fragment layout id like "R.layout.fragment_com"]

override fun init() {
...
}

希望这对您有所帮助。让我知道是否需要更多帮助！

Answer 2

我目前正在解决同一问题，查看Koin的源代码，by viewModel()提供了kotlin Lazy

/**
 * Lazy get a viewModel instance
 *
 * @param qualifier - Koin BeanDefinition qualifier (if have several ViewModel beanDefinition of the same type)
 * @param parameters - parameters to pass to the BeanDefinition
 * @param clazz
 */
fun <T : ViewModel> LifecycleOwner.viewModel(
        clazz: KClass<T>,
        qualifier: Qualifier? = null,
        parameters: ParametersDefinition? = null
): Lazy<T> = lazy { getViewModel(clazz, qualifier, parameters) }

在初始化时会调用另一个LifecycleOwner扩展方法，该方法执行viewModel实例的实际解析：

/**
 * Lazy getByClass a viewModel instance
 *
 * @param clazz - Class of the BeanDefinition to retrieve
 * @param qualifier - Koin BeanDefinition qualifier (if have several ViewModel beanDefinition of the same type)
 * @param parameters - parameters to pass to the BeanDefinition
 */
fun <T : ViewModel> LifecycleOwner.getViewModel(
        clazz: KClass<T>,
        qualifier: Qualifier? = null,
        parameters: ParametersDefinition? = null
): T {
    return getKoin().getViewModel(
            ViewModelParameters(
                    clazz,
                    this@getViewModel,
                    qualifier,
                    parameters = parameters
            )
    )
}

我还没有尝试过，但是可以肯定地说，如果我直接在BaseFragment中调用此方法，则它应该以相同的方式工作，我的BaseFragment看起来像这样：

abstract class BaseFragment<VM : ViewModel> : Fragment() {

    lateinit var viewModel: VM
    abstract val viewModelClass: KClass<VM>

    override fun onCreate(savedInstanceState: Bundle?) {
        viewModel = getViewModel(clazz = viewModelClass)

        super.onCreate(savedInstanceState)
    }

}

如何使用Koin在BaseFragment中注入viewModel

2 个答案: