inotifypropertychanged 相关问题

INotifyPropertyChanged是Microsoft .NET中定义的接口，用于通知侦听器对对象所做的数据更改。这些通知使数据绑定的UI控件能够在绑定的数据属性发生更改时自动更新其显示。

MVVM - PropertyChangedEventHandler

我从 MVVM 开始。我的应用程序使用这个“模式（PM 模式 - 我们不在这里争论这个:)）”并且工作正常；该项目非常简单，对于初学者来说应该很容易......

mvvm inotifypropertychanged

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为什么 VB.NET 编译器会认为接口没有实现，而实际上它已经实现了？

更新我认为我最初发布这个问题时还不够清楚。看看这些屏幕截图。（此处链接到更大的屏幕截图）请注意我用红色框起来的部分。班级

vb.net compiler-errors interface inotifypropertychanged

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.NET MAUI：想要将父对象传递给转换器和控件，但没有收到 OnPropertyChanged

我在 MAUI 中不断遇到这个问题，我怀疑这是由于对 MVVM 的一些基本误解造成的。假设我有：公共类学生：ObservableObject { [ObservableProperty] 字符串 _nam...

.net xaml binding maui inotifypropertychanged

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根据表格（DataGrid）的选定行设置按钮（ICommand）的操作

我有一个窗口 WPF 和 2 个表 DataGrid。 DataContext 绑定到类 PersonalTaskClassPickerViewModel.cs。 PersonalTaskClassPicker.xaml 我有一个窗口 WPF 和 2 个表 DataGrid。 DataContext 绑定到类 PersonalTaskClassPickerViewModel.cs。 PersonalTaskClassPicker.xaml <Window x:Class="WpfAppTaskPlanner.PersonalTaskClassPicker" xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation" xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml" xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006" xmlns:d="http://schemas.microsoft.com/expression/blend/2008" xmlns:viewModels="clr-namespace:WpfAppTaskPlanner.ViewModels" xmlns:views="clr-namespace:WpfAppTaskPlanner" xmlns:taskClassDirectory="clr-namespace:Library.TaskClassDirectory;assembly=Library" mc:Ignorable="d" Title="MainWindow" Height="850" Width="1500" d:DataContext="{d:DesignInstance viewModels:PersonalTaskClassPickerViewModel}"> <Window.Resources> <viewModels:OutputValueConverter x:Key="OutputValueConverter"></viewModels:OutputValueConverter> <DataTemplate x:Key="CustomDataGridHeaderTemplate"> <views:CustomDataGridHeader></views:CustomDataGridHeader> </DataTemplate> </Window.Resources> <DockPanel LastChildFill="True"> <StackPanel Orientation="Horizontal" FlowDirection="RightToLeft" DockPanel.Dock="Bottom">  <Button HorizontalAlignment="Center" VerticalAlignment="Center" Content="Удалить задачу" Width="100" Height="40" Margin="15 5" Command="{Binding RemoveTaskClassCommand}" CommandParameter="{Binding RelativeSource={RelativeSource AncestorType=Window}}"/> </StackPanel> <StackPanel DockPanel.Dock="Top"> <TextBlock Text="Связанные задачи" Margin="0 5"></TextBlock> <DataGrid x:Name="DataGridRelatedPersonalTaskClass" DockPanel.Dock="Top" ItemsSource="{Binding SelectedTaskPerformerClass.PersonalTaskClassLists.RelatedList, FallbackValue='SelectedTaskPerformerClass не не выбран'}" SelectedItem="{Binding SelectedTaskClass, Mode=TwoWay}"> <DataGrid.Columns> <DataGridTextColumn Header="Участок" HeaderTemplate="{StaticResource CustomDataGridHeaderTemplate}" Binding="{Binding BrigadeIndex}" IsReadOnly="True"/>  </DataGrid.Columns> </DataGrid> <TextBlock Text="Удаленные задачи" Margin="0 5"></TextBlock> <DataGrid x:Name="DataGridDeletedPersonalTaskClass" DockPanel.Dock="Bottom" ItemsSource="{Binding SelectedTaskPerformerClass.PersonalTaskClassLists.DeletedList, FallbackValue='SelectedTaskPerformerClass не не выбран'}" SelectedItem="{Binding SelectedTaskClass, Mode=TwoWay}"> <DataGrid.Columns> <DataGridTextColumn Header="Участок" HeaderTemplate="{StaticResource CustomDataGridHeaderTemplate}" Binding="{Binding BrigadeIndex}" IsReadOnly="True"/>  </DataGrid.Columns> </DataGrid> </StackPanel> </DockPanel> </Window> PersonalTaskClassPicker.xaml.cs public partial class PersonalTaskClassPicker { public PersonalTaskClassPicker(ref TaskPerformerClass selectedTaskPerformerClass) { InitializeComponent(); DataContext = new PersonalTaskClassPickerViewModel(ref selectedTaskPerformerClass); } } PersonalTaskClassPickerViewModel.cs public class PersonalTaskClassPickerViewModel: BaseViewModel { public PersonalTaskClassPickerViewModel(ref TaskPerformerClass selectedTaskPerformerClass) { RemoveTaskClassCommand = new RelayCommand(RemoveTaskClass, CanRemoveTaskClass); // Other ICommand's } } BaseViewModel.cs public class BaseViewModel : BaseNotifyPropertyChanged { private TaskClass? _selectedTaskClass; public TaskClass? SelectedTaskClass { get => _selectedTaskClass; set { if (Equals(value, _selectedTaskClass)) { return; } if (SetField(ref _selectedTaskClass, value)) { CallRaiseCanExecuteChanged(RemoveTaskClassCommand); } } } private TaskPerformerClass? _selectedTaskPerformerClass; public TaskPerformerClass? SelectedTaskPerformerClass { get => _selectedTaskPerformerClass; set { if (_selectedTaskPerformerClass != value) { _selectedTaskPerformerClass = value; OnPropertyChanged(); } } } public ICommand? RemoveTaskClassCommand { get; protected init; } public static void CallRaiseCanExecuteChanged(ICommand? command) { switch (command) { case AsyncRelayCommandWithParameter getToWorkCommand: getToWorkCommand.RaiseCanExecuteChanged(); break; case RelayCommand getToWorkCommand: getToWorkCommand.RaiseCanExecuteChanged(); break; } } protected bool CanRemoveTaskClass(object parameter) { if (parameter is not PersonalTaskClassPicker { DataContext: PersonalTaskClassPickerViewModel personalTaskClassPickerViewModel }) { return false; } if (personalTaskClassPickerViewModel.SelectedTaskPerformerClass is null) { MessageBox.Show("personalTaskClassPickerViewModel.SelectedTaskPerformerClass is null"); } else { var taskPerformer = personalTaskClassPickerViewModel.SelectedTaskPerformerClass; if (SelectedTaskClass is not null && taskPerformer.PersonalTaskClassLists.RelatedList is not null && taskPerformer.PersonalTaskClassLists.RelatedList.Contains(SelectedTaskClass)) { return true; } } return false; } protected void RemoveTaskClass(object parameter) { if (parameter is not PersonalTaskClassPicker { DataContext: PersonalTaskClassPickerViewModel personalTaskClassPickerViewModel }) { return; } if (personalTaskClassPickerViewModel.SelectedTaskPerformerClass is null) { MessageBox.Show("personalTaskClassPickerViewModel.SelectedTaskPerformerClass is null"); } else { var personalTaskClassListsOfTaskPerformerClass = personalTaskClassPickerViewModel.SelectedTaskPerformerClass.PersonalTaskClassLists; var selectedTaskClass = SelectedTaskClass; if (selectedTaskClass is not null && personalTaskClassListsOfTaskPerformerClass.RelatedList is not null && personalTaskClassListsOfTaskPerformerClass.RelatedList.Contains(selectedTaskClass)) { personalTaskClassListsOfTaskPerformerClass.RelatedList.Remove(selectedTaskClass); personalTaskClassListsOfTaskPerformerClass.DeletedList ??= new ObservableCollection<TaskClass>(); personalTaskClassListsOfTaskPerformerClass.DeletedList.Add(selectedTaskClass); personalTaskClassListsOfTaskPerformerClass.OnPropertyChanged( nameof(personalTaskClassListsOfTaskPerformerClass.RelatedList) ); personalTaskClassListsOfTaskPerformerClass.OnPropertyChanged( nameof(personalTaskClassListsOfTaskPerformerClass.DeletedList) ); CallRaiseCanExecuteChanged(RemoveTaskClassCommand); } } } } BaseNotifyPropertyChanged.cs public class BaseNotifyPropertyChanged : INotifyPropertyChanged { public event PropertyChangedEventHandler? PropertyChanged; protected virtual void OnPropertyChanged([CallerMemberName] string? propertyName = null) { PropertyChanged?.Invoke(this, new PropertyChangedEventArgs(propertyName)); } protected bool SetField<T>(ref T field, T value, [CallerMemberName] string? propertyName = null) { if (EqualityComparer<T>.Default.Equals(field, value)) { return false; } field = value; OnPropertyChanged(propertyName); return true; } protected class RelayCommand : ICommand { private readonly Action<object> _execute; private readonly Predicate<object>? _canExecute; public RelayCommand(Action<object> execute, Predicate<object>? canExecute = null) { _execute = execute ?? throw new ArgumentNullException(nameof(execute)); _canExecute = canExecute; } public bool CanExecute(object? parameter) => _canExecute == null || _canExecute(parameter ?? "<N/A>"); public void Execute(object? parameter) { _execute(parameter ?? "<N/A>"); } public event EventHandler? CanExecuteChanged { add => CommandManager.RequerySuggested += value; remove => CommandManager.RequerySuggested -= value; } public void RaiseCanExecuteChanged() { CommandManager.InvalidateRequerySuggested(); } } //Other AsyncRelayCommand's } 从主 WPF 窗口调用 WPF 窗口，如下所示： public class MainViewModel : BaseViewModel { //Other code private static void OnEditPersonalTaskClassList(object parameter) { if (parameter is not TaskPerformerClass selectedTaskPerformerClass) { return; } var personalTaskClassEditor = new PersonalTaskClassPicker(ref selectedTaskPerformerClass); if (personalTaskClassEditor.ShowDialog() == true) { //Other commands } else { MessageBox.Show("DataContext закрытого окна не является типом TaskPerformerClass"); } } } TaskPerformerClass.cs namespace Library.TaskPerformerDirectory; public sealed class TaskPerformerClass : INotifyPropertyChanged { //Other private values private PersonalTaskClassCollection _personalTaskClassLists = null!; private TaskPerformerClass() { } public TaskPerformerClass( FullNameOfThePerson fullName, WorkDay workDay, CalendarYearOfTaskPerformer calendarYearOfTaskPerformer, int bitrixEmployeeIndex, List<Department>? bitrixEmployeeDepartmentList = null, TaskClass? actualTask = null ) { //Other initializations of properties PersonalTaskClassLists = new PersonalTaskClassCollection(this); } //Other property public PersonalTaskClassCollection PersonalTaskClassLists { get => _personalTaskClassLists; set { if (Equals(value, _personalTaskClassLists)) { return; } _personalTaskClassLists = value; OnPropertyChanged(); } } public event PropertyChangedEventHandler? PropertyChanged; public void OnPropertyChanged([CallerMemberName] string? propertyName = null) { PropertyChanged?.Invoke(this, new PropertyChangedEventArgs(propertyName)); } private bool SetField<T>(ref T field, T value, [CallerMemberName] string? propertyName = null) { if (EqualityComparer<T>.Default.Equals(field, value)) { return false; } field = value; OnPropertyChanged(propertyName); return true; } } PersonalTaskClassCollection.cs public sealed class PersonalTaskClassCollection : INotifyPropertyChanged { private int _id; private int _taskPerformerClassId; private TaskPerformerClass _taskPerformerClass = null!; private ObservableCollection<TaskClass>? _completedList; private ObservableCollection<TaskClass>? _deletedList; private ObservableCollection<TaskClass>? _relatedList; private PersonalTaskClassCollection() { } public PersonalTaskClassCollection(TaskPerformerClass taskPerformerClass) => TaskPerformerClass = taskPerformerClass; public int Id { get => _id; set { if (value == _id) { return; } _id = value; OnPropertyChanged(); } } public int TaskPerformerClassId { get => _taskPerformerClassId; set { if (value == _taskPerformerClassId) { return; } _taskPerformerClassId = value; OnPropertyChanged(); } } public TaskPerformerClass TaskPerformerClass { get => _taskPerformerClass; set { if (Equals(value, _taskPerformerClass)) { return; } _taskPerformerClass = value; OnPropertyChanged(); } } public ObservableCollection<TaskClass>? RelatedList { get => _relatedList; set { if (Equals(value, _relatedList)) { return; } _relatedList = value; OnPropertyChanged(); } } public ObservableCollection<TaskClass>? DeletedList { get => _deletedList; set { if (Equals(value, _deletedList)) { return; } _deletedList = value; OnPropertyChanged(); } } public ObservableCollection<TaskClass>? CompletedList { get => _completedList; set { if (Equals(value, _completedList)) { return; } _completedList = value; OnPropertyChanged(); } } public event PropertyChangedEventHandler? PropertyChanged; public void OnPropertyChanged([CallerMemberName] string? propertyName = null) { PropertyChanged?.Invoke(this, new PropertyChangedEventArgs(propertyName)); } private bool SetField<T>(ref T field, T value, [CallerMemberName] string? propertyName = null) { if (EqualityComparer<T>.Default.Equals(field, value)) { return false; } field = value; OnPropertyChanged(propertyName); return true; } } 我认为描述“TaskClass.cs”类没有任何意义。它只是一个包含任务属性的类。在“DataGridRelatedPersonalTaskClass”和“DataGridDeletedPersonalTaskClass”这两个表中随机选择一行后，“RemoveTaskClassCommand”按钮将永远无法更改“set”属性“SelectedTaskClass”的值。因此，如果单击它，“DataGridRelatedPersonalTaskClass”中下一个突出显示的任务将被删除。随着时间的推移，我意识到，如果我突出显示表中的每个问题，那么每个“DataGrid”的“SelectedItem”属性将继续处于活动状态，但我的“SelectedTaskClass”属性并不总是更新。尽管“IsMouseOver”属性始终正确显示我最后突出显示的表中的行。当选择“DataGridRelatedPersonalTaskClass”表中的一行时，我想正确配置“RemoveTaskClassCommand”按钮的活动。怎么办？首先，有一个重要的说明。您传递 Window 命令参数 CommandParameter="{Binding RelativeSource={RelativeSource AncestorType=Window}}"。由于此命令是一个 ViewModel 实体，并且根据 MVVM 规则，禁止将任何 UI 元素传递给 ViewModel，那么您的实现实际上完全破坏了 MVVM 合规性。关于你问题的本质。您的任务的可能实现选项之一的最简化示例。 namespace Core2024.SO.Zhan.question79147702 { public class SomeTextItem { private string _title = string.Empty; private string _text = string.Empty; private string _description = string.Empty; public string Title { get => _title; set => _title = value ?? string.Empty; } public string Text { get => _text; set => _text = value ?? string.Empty; } public string Description { get => _description; set => _description = value ?? string.Empty; } } } using Simplified; // This is the space with my implementation of INotifyPropertyChanged and ICommand interfaces. You can use your own implementations instead. using System.Collections.ObjectModel; namespace Core2024.SO.Zhan.question79147702 { public class SomeTextViewModel { private const string data = "After randomly selecting a row in each of the 2 tables \"DataGridRelatedPersonalTaskClass\" and \"DataGridDeletedPersonalTaskClass\", the \"RemoveTaskClassCommand\" button will never be able to change the value of the \"set\" property \"SelectedTaskClass\". Thus, if you click on it, the next highlighted task in the \"DataGridRelatedPersonalTaskClass\" will be deleted. Over time, I realized that if I highlighted each question in the tables, then the \"SelectedItem\" properties of each \"DataGrid\" continue to be active, but my \"SelectedTaskClass\" property is not always updated.Although the \"IsMouseOver\" property always correctly displays the row in which table I highlighted last."; private static IEnumerable<SomeTextItem> GetItems() { string[] split = data.Split(); for (int i = 2; i < split.Length; i+=3) { yield return new SomeTextItem() { Title = split[i-2], Text = split[i-1], Description = split[i] }; } } public SomeTextViewModel() { TextItems = new ObservableCollection<SomeTextItem>(GetItems()); RemoveTextItem = new RelayCommand<SomeTextItem> ( item => TextItems.Remove(item), item => TextItems.Contains(item) ); } public ObservableCollection<SomeTextItem> TextItems { get; } public RelayCommand RemoveTextItem { get; } } } <Window x:Class="Core2024.SO.Zhan.question79147702.SomeTextWindow" xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation" xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml" xmlns:d="http://schemas.microsoft.com/expression/blend/2008" xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006" xmlns:local="clr-namespace:Core2024.SO.Zhan.question79147702" mc:Ignorable="d" Title="SomeTextWindow" Height="450" Width="800" DataContext="{DynamicResource vm}"> <Window.Resources> <local:SomeTextViewModel x:Key="vm"/> </Window.Resources> <Grid> <DataGrid ItemsSource="{Binding TextItems}"> <DataGrid.Columns> <DataGridTemplateColumn> <DataGridTemplateColumn.CellTemplate> <DataTemplate DataType="{x:Type local:SomeTextItem}"> <Button Content="Remove Item" CommandParameter="{Binding Mode=OneWay}" Command="{Binding RemoveTextItem, Mode=OneWay, Source={StaticResource vm}}"/> </DataTemplate> </DataGridTemplateColumn.CellTemplate> </DataGridTemplateColumn> </DataGrid.Columns> </DataGrid> </Grid> </Window>

wpf datagrid inotifypropertychanged relaycommand

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OnPropertyChanged 在 Blazor（MAUI 混合）中无法正常工作

我已经在 MauiProgram.cs 中注册了一个服务： builder.Services.AddSingleton(); 服务等级：公共类 NetworkStatusService ：INotifyPropertyChanged { 私人

c# blazor maui inotifypropertychanged propertychanged

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WPF DataContext PropertyChanged 为空

我有两个 WPF 组件，一个包含另一个的列表。我在父 WPF 组件中设置了 DataContext，因此我可以定义一个属性。不幸的是，我的模型的 PropertyChanged 是

c# wpf data-binding inotifypropertychanged datacontext

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访问视图模型之间的依赖属性

我有 2 个视图模型， viewmodel 绑定到 view A 类：INotifyPropertyChanged { 公共 A(){} 私人布尔_propertya；公共 bool 属性A { 获取{返回_propertya;} 设置{_propertya=值；