要解决Android的可组合组件在从Room数据库中删除项目后不重新组合的问题,你可以使用Flow和StateFlow来实现数据的实时更新。以下是一个示例解决方案的代码示例:
@Dao
interface ProjectDao {
@Query("SELECT * FROM project_table")
fun getAllProjects(): Flow>
}
class ProjectViewModel : ViewModel() {
private val _projects = MutableStateFlow>(emptyList())
val projects: StateFlow> = _projects
fun getAllProjects() {
viewModelScope.launch {
projectDao.getAllProjects().collect {
_projects.value = it
}
}
}
fun deleteProject(project: Project) {
viewModelScope.launch {
projectDao.deleteProject(project)
// 项目删除后,由于Flow的实时更新,会自动更新_projects的值
}
}
}
@Composable
fun ProjectListScreen(viewModel: ProjectViewModel) {
val projects by viewModel.projects.collectAsState()
LazyColumn {
items(projects) { project ->
Text(project.name)
}
}
}
这样,当你调用deleteProject()
删除项目时,项目列表会自动更新,并且Compose界面会重新组合UI以反映这些更改。