在数据绑定中未观察到 Stateflow 值

Question

我有一个状态流，它为我提供来自 ViewModel 的可变状态流的值，我想做的是，我想根据按钮单击显示隐藏 Web 视图。当值为 true 时，我想显示 Web 视图，当我想隐藏它时，我将其值更改为 false。这些值已正确更新，但未反映内部数据绑定。 这是我的视图模型

class ArticleDetailsViewModel : ViewModel() {
    private val _isWebViewShowing = MutableStateFlow(false)
    val isWebViewShowing: StateFlow<Boolean>
        get() = _isWebViewShowing

    fun onReadMoreClicked() {

        _isWebViewShowing.value = true
    }

    fun changeWebViewState() {
        _isWebViewShowing.value = false
    }}

这是我正在进行比较的 XML

<?xml version="1.0" encoding="utf-8"?>
<layout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools">

    <data>
        <variable
            name="article"
            type="io.infinity.newsapp.model.domain.ArticleDomainModel" />
        <variable
            name="viewModel"
            type="io.infinity.newsapp.viewmodels.ArticleDetailsViewModel" />
        <import type="android.view.View"/>
    </data>

    <androidx.constraintlayout.widget.ConstraintLayout
        android:layout_width="match_parent"
        android:layout_height="match_parent">
        <include
            android:id="@+id/toolbar"
            layout="@layout/toolbar_generic"
            />

        <LinearLayout
            android:layout_width="match_parent"
            android:layout_height="0dp"
            android:visibility="@{viewModel.isWebViewShowing().value ?  View.INVISIBLE :View.VISIBLE  }"
            android:orientation="vertical"
            app:layout_constraintBottom_toBottomOf="parent"
            app:layout_constraintEnd_toEndOf="@+id/toolbar"
            app:layout_constraintStart_toStartOf="@+id/toolbar"
            app:layout_constraintTop_toBottomOf="@+id/toolbar">


            <com.google.android.material.card.MaterialCardView
                android:layout_width="match_parent"
                app:cardCornerRadius="@dimen/_20sdp"
                android:layout_margin="@dimen/_16sdp"
                android:layout_height="250dp">
                <ImageView
                    android:layout_width="match_parent"
                    android:layout_height="match_parent"
                    loadImageFromUrl="@{article.urlToImage}"
                    android:scaleType="centerCrop"/>
            </com.google.android.material.card.MaterialCardView>
            <TextView
                android:id="@+id/textView"
                style="@style/eighteen_sp_muli_bold"
                android:layout_width="match_parent"
                android:layout_height="wrap_content"
                android:layout_margin="@dimen/_8sdp"
                android:text="@{article.title}"
                app:layout_constraintEnd_toEndOf="parent"
                app:layout_constraintStart_toStartOf="parent"
                app:layout_constraintTop_toTopOf="parent" />
            <LinearLayout
                android:layout_width="match_parent"
                android:layout_margin="@dimen/_16sdp"
                android:orientation="horizontal"
                android:layout_height="wrap_content">
                <TextView
                    android:id="@+id/tvAuthor"
                    style="@style/twelve_sp_muli_extra_bold"
                    android:layout_width="match_parent"
                    android:layout_weight="1"
                    android:layout_height="wrap_content"
                    android:gravity="start"
                    android:layout_marginStart="8dp"
                    android:text="@{article.author}"
                    android:textAllCaps="true"
                    android:textColor="@color/semi_black"
                    />
                <ImageView
                    android:id="@+id/imageView2"
                    android:layout_width="20dp"
                    android:layout_height="20dp"
                    android:layout_marginStart="@dimen/_4sdp"
                    android:layout_marginEnd="@dimen/_2sdp"
                    app:layout_constraintBottom_toBottomOf="parent"
                    app:layout_constraintStart_toStartOf="@+id/tvTitle"
                    app:srcCompat="@drawable/circle_blue" />

                <TextView
                    android:id="@+id/tvSource"
                    style="@style/twelve_sp_muli_extra_bold"
                    android:layout_width="100dp"
                    android:layout_height="wrap_content"
                    android:layout_marginStart="8dp"
                    android:text="@{article.source.name}"
                    android:textAllCaps="true"
                    android:textColor="@color/semi_black"
                    app:layout_constraintBottom_toBottomOf="@+id/imageView2"
                    app:layout_constraintStart_toEndOf="@+id/imageView2"
                    app:layout_constraintTop_toTopOf="@+id/imageView2" />
                <TextView
                    android:id="@+id/publishedOn"
                    android:gravity="end"
                    style="@style/twelve_sp_muli_extra_bold"
                    android:layout_width="match_parent"
                    android:layout_height="wrap_content"
                    android:layout_weight="1"
                    android:layout_marginStart="8dp"
                    setDateAndTime="@{article.publishedAt}"
                    android:textAllCaps="true"
                    android:textColor="@color/semi_black"
                    />


            </LinearLayout>
            <TextView
                android:layout_width="match_parent"
                style="@style/fourteen_sp_muli_bold"
                android:text="@{article.description}"
                android:layout_marginStart="@dimen/_16sdp"
                android:layout_marginEnd="@dimen/_16sdp"
                android:layout_marginTop="@dimen/_16sdp"
                android:layout_marginBottom="0dp"
                android:layout_height="wrap_content"/>
            <TextView
                android:id="@+id/tvReadMore"
                android:onClick="@{() -> viewModel.onReadMoreClicked()}"
                android:layout_width="match_parent"
                style="@style/twelve_sp_muli_regular"
                android:text="@string/read_more"
                android:textColor="@color/light_blue"
                android:layout_marginStart="@dimen/_16sdp"
                android:layout_height="wrap_content"/>

        </LinearLayout>

        <WebView
            android:id="@+id/webView"
            loadArticleInWeb="@{article.url}"
            android:layout_width="match_parent"
            android:layout_height="match_parent"
            android:visibility="@{viewModel.isWebViewShowing().value ? View.VISIBLE :View.INVISIBLE}"
            app:layout_constraintBottom_toBottomOf="parent"
            app:layout_constraintEnd_toEndOf="parent"
            app:layout_constraintStart_toStartOf="parent"
            app:layout_constraintTop_toTopOf="parent" />
    </androidx.constraintlayout.widget.ConstraintLayout>
</layout>

Answer 1

尝试添加 -> binding.lifecycleOwner = this@YourFragment

Answer 2

我遇到了类似的问题。我在片段的布局文件中有另一个视图。我通过在片段中的视图声明中传递模型来解决问题

fragment.xml
<include
    android:id="@+id/lyt_min_kyc_update_guidance"
    layout="@layout/view_min_kyc_update_guidance"
    model="@{model}"
    tools:visibility="visible" />

view.xml
<variable
    name="model"
type="com.balancehero.truebalance.account.viewmodel.AccountLoggedInViewModel" />

 <androidx.constraintlayout.widget.ConstraintLayout
        android:id="@+id/view_guidance_min_kyc_update"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:background="@color/orange_base"
        android:visibility="@{model.showViewGuidanceMinKycWallet}">