如何使用SavedStateHandle和导航安全Args [英] How to use SavedStateHandle and navigation Safe Args

问题描述

我有两个选项可以在片段之间传递数据，即导航的安全args和viewModel的SavedStateHandle，它们之间有什么区别以及如何在正确的位置使用它们?

I have two options to pass data between fragment, the navigation's safe args and viewModel's SavedStateHandle, what's the difference between them and how to use them in the correct place?

推荐答案

如果您使用hilt，则可以像这样将进入的参数包装在片段(和其他组件)中

If you are using hilt you can wrap the incoming arguments in the fragment (and other components) like so

open class BaseFragment : Fragment() { // Inherit your fragment from this

    override fun setArguments(args: Bundle?) {
        if (args != null) {
            super.setArguments(Bundle(args).apply {
                putBundle(BUNDLE_ARGS, args) // Wrap the arguments as BUNDLE_ARGS
            })
        } else {
            super.setArguments(null)
        }
    }
}

然后对于视图模型，您可以从类似的东西继承

and then for the view model, you can inherit from something like that

open class ArgsViewModel(private val savedStateHandle: SavedStateHandle) : ViewModel() {

    val arguments get() = savedStateHandle.get<Bundle>(BUNDLE_ARGS)

    @MainThread
    inline fun <reified Args : NavArgs> navArgs() = NavArgsLazy(Args::class) {
        arguments ?: throw IllegalStateException("ViewModel $this has null arguments")
    }
}

然后像使用安全参数一样使用它

And then use it just like you would use safe args

class FooViewModel @ViewModelInject constructor(
    @Assisted savedStateHandle: SavedStateHandle
) : ArgsViewModel(savedStateHandle) {

    private val args: FooFragmentArgs by navArgs()
}

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