Android 观察DialogFragment中的Viewmodel Livedata

我有一个

Viewmodel

，里面有一些

Livedata

参数。其中一个

Livedata

参数（

clickedItem

）更改旨在触发

对话框片段

在
DialogFragment
的
OnCreateDialog（savedInstanceState:Bundle？
方法中，我提取并使用所述
Livedata
参数中的数据来做某件事

以下是
clickedItem
observer方法：

clickedItem.observe(viewLifecycleOwner, Observer { clickedItem ->
                if (clickedItem != null && !dialogIsDisplayed) {
                    showAddItemDialog()
                }
            })

以下是
对话框片段
的
OnCreateDialog（savedInstanceState:Bundle？
方法：

override fun onCreateDialog(savedInstanceState: Bundle?): Dialog {
        return activity?.let {
            val builder = AlertDialog.Builder(it)

            binding = DataBindingUtil.inflate(
                requireActivity().layoutInflater,
                R.layout.business_inventory_selection_item_dialog, null, false
            )

            //Attach viewmodel to this fragment.
            setupViewModel()

            builder.setView(binding.root)

            bindView(viewModel.clickedItem.value!!)

            builder.create()

        } ?: throw IllegalStateException("Activity cannot be null")
    }

private fun setupViewModel() {
        activity?.run {
            viewModel = ViewModelProviders.of(this)
                .get(BusinessInventorySelectionViewModel::class.java)
            with(viewModel) {
                itemBrand.value = null
                unitOfMeasurement.value = null
            }
        }
        bindViewModel()
    }

private fun bindViewModel() {
    binding.apply {
        businessinventoryselectionviewmodel = viewModel
        lifecycleOwner = this@ItemSelectionDialogFragment
    }
}

override fun onCreateView(
        inflater: LayoutInflater,
        container: ViewGroup?,
        savedInstanceState: Bundle?
    ): View? {
        bindView(viewModel.clickedItem.value!!)
        return binding.root
    }

下面是
setupViewModel（）
方法：

override fun onCreateDialog(savedInstanceState: Bundle?): Dialog {
        return activity?.let {
            val builder = AlertDialog.Builder(it)

            binding = DataBindingUtil.inflate(
                requireActivity().layoutInflater,
                R.layout.business_inventory_selection_item_dialog, null, false
            )

            //Attach viewmodel to this fragment.
            setupViewModel()

            builder.setView(binding.root)

            bindView(viewModel.clickedItem.value!!)

            builder.create()

        } ?: throw IllegalStateException("Activity cannot be null")
    }

private fun setupViewModel() {
        activity?.run {
            viewModel = ViewModelProviders.of(this)
                .get(BusinessInventorySelectionViewModel::class.java)
            with(viewModel) {
                itemBrand.value = null
                unitOfMeasurement.value = null
            }
        }
        bindViewModel()
    }

private fun bindViewModel() {
    binding.apply {
        businessinventoryselectionviewmodel = viewModel
        lifecycleOwner = this@ItemSelectionDialogFragment
    }
}

override fun onCreateView(
        inflater: LayoutInflater,
        container: ViewGroup?,
        savedInstanceState: Bundle?
    ): View? {
        bindView(viewModel.clickedItem.value!!)
        return binding.root
    }

现在的问题是：当我尝试使用包装在
clickedItem
中的数据时，我发现它包含上次更改的数据，而不是导致
对话框片段
触发器的最新数据。
在使用
clickedItem
中的最新数据之前，我必须检查
clickedItem
中存储的所有数据。我找到了类似以下问题的修复方法：

我没有在
onCreateDialog（savedInstanceState:Bundle？
中调用
bindView（viewModel.clickedItem.value！！）
，而是在
onCreateView（充气机：布局扁平机，容器：视图组？，savedInstanceState:Bundle？）中调用它
方法：

override fun onCreateDialog(savedInstanceState: Bundle?): Dialog {
        return activity?.let {
            val builder = AlertDialog.Builder(it)

            binding = DataBindingUtil.inflate(
                requireActivity().layoutInflater,
                R.layout.business_inventory_selection_item_dialog, null, false
            )

            //Attach viewmodel to this fragment.
            setupViewModel()

            builder.setView(binding.root)

            bindView(viewModel.clickedItem.value!!)

            builder.create()

        } ?: throw IllegalStateException("Activity cannot be null")
    }

private fun setupViewModel() {
        activity?.run {
            viewModel = ViewModelProviders.of(this)
                .get(BusinessInventorySelectionViewModel::class.java)
            with(viewModel) {
                itemBrand.value = null
                unitOfMeasurement.value = null
            }
        }
        bindViewModel()
    }

private fun bindViewModel() {
    binding.apply {
        businessinventoryselectionviewmodel = viewModel
        lifecycleOwner = this@ItemSelectionDialogFragment
    }
}

override fun onCreateView(
        inflater: LayoutInflater,
        container: ViewGroup?,
        savedInstanceState: Bundle?
    ): View? {
        bindView(viewModel.clickedItem.value!!)
        return binding.root
    }

这就解决了问题。
我将此作为一个自我问答，以便对那些面对这一问题的人有所帮助。干杯