在 kotlin 中单击按钮时更改 ViewModel 中的字符串值，然后将该值存储在房间数据库中

Question

我正在尝试将 debtCategory 的值更改为“贷款人”或“借款人”。我在我的视图模型中引入了两种方法来更新 debtCategory。这是逻辑：

如果用户单击 addLender，则调用视图模型中的 updateLender 方法，用“Lender”值更新 debtCategory
如果用户点击 addBorrower 然后 updateBorrower 视图模型中的方法被调用更新 debtCategory 与“借款人”值

到目前为止没有错误，但是 debtCatery 没有相应地更新。非常感谢您的帮助。

提前致谢

这是我的代码：

1.视图模型

import android.content.Context
import android.text.Editable
import android.util.Log
import android.widget.ArrayAdapter
import android.widget.AutoCompleteTextView
import androidx.databinding.Bindable
import androidx.databinding.Observable
import androidx.lifecycle.LiveData
import androidx.lifecycle.MutableLiveData
import androidx.lifecycle.ViewModel
import androidx.lifecycle.viewModelScope
import com.droid.f.debtmanagement.R
import com.droid.f.debtmanagement.models.Debtor
import com.droid.f.debtmanagement.repository.DebtManagementRepository
import com.droid.f.debtmanagement.util.Util
import kotlinx.coroutines.Job
import kotlinx.coroutines.launch

class DebtViewModel(private val debtManagementRepository: DebtManagementRepository)
    : ViewModel(),Observable {
    //all debtors
    val allLenders = debtManagementRepository.getAllLenders()
    val allBorrowers = debtManagementRepository.getAllBorrowers()

    private val util = Util()

    var debtCategory: String = ""

    @Bindable
    val clientName = MutableLiveData<String>()
    @Bindable
    val phoneNumber = MutableLiveData<String>()
    @Bindable
    val debtorAmount = MutableLiveData<String>()
    @Bindable
    val amountPaid = MutableLiveData<String>()
    @Bindable
    val period = MutableLiveData<String>()
    private val datelend = MutableLiveData<String>()
    private val dateToPay = MutableLiveData<String>()
    private val debtStatus = MutableLiveData<String>()
    private val timeBorrowed = MutableLiveData<String>()
    private val remainingAmount = MutableLiveData<Double>()

    init {
        debtStatus.value = "Pending"
    }

    fun saveUpdate(){
        val debtorName: String = clientName.value!!
        val debtorPhone: String = phoneNumber.value!!
        val debtAmount: Double = debtorAmount.value!!.toDouble()
        val period: Int = monthsToDays()
        val debtAmountPaid: Double = amountPaid.value!!.toDouble()
        val debtorDateLend: String = dateBorrowedLend()
        val debtorDateToPay: String = _dueDate()
        val debtorStatus: String = checkProgress()
        val debtTimeBorrowed: String = exactTimeBorrowed()
        val remainingAmount: Double = remainingAmount()
        val dtCategory: String = debtCategory

        insertDebtor(
            Debtor(
            0, dtCategory, debtorName, debtorPhone, debtAmount, debtAmountPaid,period, debtorDateLend, debtorDateToPay, debtorStatus,
            debtTimeBorrowed, remainingAmount
        ))
        clearFields()
    }

    fun clearFields(){
        clientName.value = null
        phoneNumber.value = null
        debtorAmount.value = null
        period.value = null
        amountPaid.value = null
    }

    fun updateLender(){
        debtCategory = "Lender"
    }

    fun updateBorrower(){
        debtCategory = "Borrower"
    }
    //Months to Date
    private fun monthsToDays(): Int{
        return util.monthsToDays(period.value!!.toInt())
    }
    //Date borroewed/lend
    private fun dateBorrowedLend(): String{
        return util.dateNow()
    }

    //Time borrowed/lend
    private fun exactTimeBorrowed(): String{
        return util.timeNow()
    }
    //Due date method
    private fun _dueDate(): String{
        return util.dueDate(util.monthsToDays(period.value!!.toInt()))
    }
    //remaining amount method
    private fun remainingAmount(): Double{
        return util.remainingDebt(debtorAmount.value!!.toDouble(), amountPaid.value!!.toDouble())
    }

    //check progress
    private fun checkProgress(): String{
        return util.checkProgress(debtorAmount.value!!.toDouble(), amountPaid.value!!.toDouble())
    }

    private fun insertDebtor(debtor: Debtor): Job = viewModelScope.launch {
            debtManagementRepository.insertDebtor(debtor)
    }

    fun updateDebtor(debtor: Debtor): Job = viewModelScope.launch {
        debtManagementRepository.updateDebtor(debtor)
    }

    fun deleteDebtor(debtor: Debtor): Job = viewModelScope.launch {
        debtManagementRepository.deleteDebtor(debtor)
    }

    fun deleteAllDebtors(): Job = viewModelScope.launch {
        debtManagementRepository.deleteAllDebtors()
    }

    override fun addOnPropertyChangedCallback(callback: Observable.OnPropertyChangedCallback?) {

    }

    override fun removeOnPropertyChangedCallback(callback: Observable.OnPropertyChangedCallback?) {

    }

}

2。主要活动：

class MainActivity : AppCompatActivity() {
lateinit var binding: ActivityMainBinding
private var mDebtViewModel: DebtViewModel? = null
private lateinit var repository: DebtManagementRepository
private lateinit var factory: DebtManagementViewModelFactory
private lateinit var debtDatabase: DebtManagementDatabase

//initialize animation files
private val rotateOpen: Animation by lazy{ AnimationUtils.loadAnimation(this, R.anim.rotate_to_open_anim)}
private val rotateToClose: Animation by lazy { AnimationUtils.loadAnimation(this, R.anim.rotate_to_close_anim) }
private val fromBottom: Animation by lazy { AnimationUtils.loadAnimation(this, R.anim.from_bottom_anim) }
private val toBottom: Animation by lazy { AnimationUtils.loadAnimation(this, R.anim.to_bottom_anim) }

private var isOpen: Boolean = false

override fun onCreate(savedInstanceState: Bundle?) {
    super.onCreate(savedInstanceState)
    binding = DataBindingUtil.setContentView(this, R.layout.activity_main)
    debtDatabase = DebtManagementDatabase.getDataBase(this)
    repository = DebtManagementRepository(debtDatabase)
    factory = DebtManagementViewModelFactory(repository)
    mDebtViewModel = ViewModelProvider(this, factory).get(DebtViewModel::class.java)
    binding.debtViewModel = mDebtViewModel
    binding.lifecycleOwner = this

    binding.addFab.setOnClickListener {
        onAddFabClicked()
    }

    binding.addLender.setOnClickListener {
        newDebtorActivity()
        mDebtViewModel!!.updateLender()
    }

    binding.addBorrower.setOnClickListener {
        newDebtorActivity()
        mDebtViewModel!!.updateBorrower()
    }

    addTabsAndIntializePager()
}

private fun onAddFabClicked() {
    setVisibility(isOpen)
    setAnimation(isOpen)
    isOpen = !isOpen
}

private fun setVisibility(isOpen: Boolean) {
    if (!isOpen){
        binding.addBorrower.visibility = View.VISIBLE
        binding.addLender.visibility = View.VISIBLE
    }else{
        binding.addBorrower.visibility = View.INVISIBLE
        binding.addLender.visibility = View.INVISIBLE
    }
}

private fun setAnimation(isOpen: Boolean) {
    if (!isOpen){
        binding.addFab.startAnimation(rotateOpen)
        binding.addLender.startAnimation(fromBottom)
        binding.addBorrower.startAnimation(fromBottom)
    }else{
        binding.addFab.startAnimation(rotateToClose)
        binding.addLender.startAnimation(toBottom)
        binding.addBorrower.startAnimation(toBottom)
    }
}

private fun newDebtorActivity() {
    startActivity(Intent(this, EditActivity::class.java))
    binding.addBorrower.visibility = View.INVISIBLE
    binding.addLender.visibility = View.INVISIBLE
}

private fun addTabsAndIntializePager() {
    binding.viewPager.adapter = ViewPagerAdapter(supportFragmentManager, lifecycle)
    TabLayoutMediator(binding.debtManagementTab, binding.viewPager){tab, position->
        when(position){
            0->{
               tab.text = "Borrowers"
            }
            1->{
                tab.text = "Lenders"
            }
        }
    }.attach()
}

}

Answer 1

你的Viewmodelclass没问题。问题出在 MainActivity 中的 2 个方法上在这里，您在更新值之前导航下一个 activity。您需要在调用 newDebtorActivity()

之前调用 mDebtViewModel!!.updateLender() 和 mDebtViewModel!!.updateBorrower()

这是您的代码

binding.addLender.setOnClickListener {
        newDebtorActivity()
        mDebtViewModel!!.updateLender()
    }

    binding.addBorrower.setOnClickListener {
        newDebtorActivity()
        mDebtViewModel!!.updateBorrower()
    }

应该是

binding.addLender.setOnClickListener {
        mDebtViewModel!!.updateLender()
        newDebtorActivity()
        
    }

    binding.addBorrower.setOnClickListener {
        mDebtViewModel!!.updateBorrower()
        newDebtorActivity()
    }

Answer 2

与其将 debtCategory 设为字符串，不如将其更改为可变的实时数据

...
    // from var debtCategory: String = ""
    // change it to
    val debtCategory = MutableLiveData<String>()
...

比 make 函数更新它

    fun updateDebtCategory(newValue: String){
        debtCategory.value = newValue
    }

您可以在 activity

中调用它

viewModel.updateDebtCategory("Borrower")
//or
viewModel.updateDebtCategory("Lander")

在 kotlin 中单击按钮时更改 ViewModel 中的字符串值，然后将该值存储在房间数据库中

Change String Value in ViewModel on button click in kotlin then store the value in room db

android

android-viewmodel