我的活动中的 ViewModel.Observe() 函数没有触发

Posted 2023-02-16

【中文标题】我的活动中的 ViewModel.Observe() 函数没有触发

【英文标题】：ViewModel.Observe() function in my activity doesn't trigger

【发布时间】：2020-09-08 13:37:33

【问题描述】：

我有一个从 api 获取数据的类。我已经记录了我得到的结果，所以我确信正在获取数据。但是我的活动中的 viewModel.Observe() 应该检查我的 livedata 的变化并没有被触发。下面是我的代码

class PokemonOverviewModel():ViewModel() 
private var pokemonIndividualData = MutableLiveData<PokemonIndividualDetails>()


fun getPokemonIndividualDataDetails(): LiveData<PokemonIndividualDetails> 
    return pokemonIndividualData





fun getPokemonIndividualDetails(id:String)
    viewModelScope.launch 
        try 
            val pokemonIndividualResults = pokemonApi.retrofitService.getPokemonDetails(id)


           Log.d("SUCCESSDETAILS", "$pokemonIndividualResults")
            pokemonIndividualData.setValue(pokemonIndividualResults)

         catch (e: Exception)
            Log.d("FAILUREDETAILS", "$e")
        
    

调用 viewModel.Observe() 的 Activity 类

class PokemonDetails : AppCompatActivity() 

lateinit var pokemonBinding: ActivityPokemonDetailsBinding
override fun onCreate(savedInstanceState: Bundle?) 
    super.onCreate(savedInstanceState)
    pokemonBinding = DataBindingUtil.setContentView(this,R.layout.activity_pokemon_details)

     var height_details = pokemonBinding.heightDetails





    var string = intent.getStringExtra("NUM")

     PokemonOverviewModel().getPokemonIndividualDetails(string!!)



    Log.d("GOTTENURL", "$string")

    val viewGotten = ViewModelProvider(this).get(PokemonOverviewModel::class.java)

    viewGotten.getPokemonIndividualDataDetails().observe(this, Observer 

        Toast.makeText(this, "DATA CHANGED", Toast.LENGTH_LONG).show()

    )

【参考方案1】：

我发现我两次初始化了我的视图模型。观察函数只是观察第二个实例

class PokemonDetails : AppCompatActivity() 

lateinit var pokemonBinding: ActivityPokemonDetailsBinding
override fun onCreate(savedInstanceState: Bundle?) 
    super.onCreate(savedInstanceState)
    pokemonBinding = DataBindingUtil.setContentView(this,R.layout.activity_pokemon_details)

     var height_details = pokemonBinding.heightDetails





    var string = intent.getStringExtra("NUM")



   // height_details.text = PokemonDetailsList.getList().toString()



    Log.d("GOTTENURL", "$string")

    val viewGotten = ViewModelProvider(this).get(PokemonOverviewModel::class.java)
    
    //I added this line
    viewGotten.getPokemonIndividualDetails(string!!)

    viewGotten.getPokemonIndividualDataDetails().observe(this, Observer 

        Toast.makeText(this, "DATA CHANGED", Toast.LENGTH_LONG).show()
        height_details.text = it.height

    )

【讨论】：

哦，是的，我没有注意到，初始化是在`PokemonOverviewModel()`下面再次完成...