堆叠组合框选定的项目属性执行 [英] Stacking up combo box selected item property execution
问题描述
我有一个不寻常的问题，让我们说我有一个主要的winow应用程序：
现在您看到我将窗口拆分为两个第一部分导航，其中的按钮可以更改视图，另一部分则显示视图，在MainWindowsView模型中使用Mvvm，它看起来像xaml：
< StackPanel DockPanel 。 Dock = " Top" >
<按钮 内容 = " View 1" 命令 = " {Binding View1ViewModel}" />
< span class ="tag"><按钮 内容 = " View 2" 命令 = " {Binding View2ViewModel}" />
<按钮 内容 = " View 3 w combobox" 命令 = " {Binding ListComboboxViewModel}" />
< / StackPanel>
<网格>
< ContentControl 网格 。 行 = " 0" DataContext = " {Binding ContentControlDataContext}" 内容 = " {Binding}" />
< / Grid> 查看模型：
private readonly View1ViewModel view1ViewModel ;
private readonly View2ViewModel view2ViewModel ;
私人 readonly ListComboboxViewModel listComboboxViewModel ;
public ICommand SetView1ViewModel { get ; set ; }
public ICommand SetView2ViewModel { get ; set ; }
public ICommand SetListComboboxViewModel { get ; set ; }
public object ContentControlDataContext
{
get => this 。 contentControlDataContext ;
set
{
此 。 contentControlDataContext = value ;
OnPropertyChanged （）;
}
}
public MainViewModel （）
{
此 。 view1ViewModel = new View1ViewModel （）;
此 。 view2ViewModel = new View2ViewModel （）;
此 。 listComboboxViewModel = new ListComboboxViewModel （）;
this 。 SetView1ViewModel = new 命令 （ p => ContentControlDataContext = 此 。 view1ViewModel ）;
this 。 View2ViewModel = new 命令 （ p => ContentControlDataContext = 此 。 view2ViewModel ）;
此 。 < span class ="typ"> SetListComboboxViewModel = new 命令 （ p => ContentControlDataContext = 此 。 listComboboxViewModel ）;
} 基本上一切在这个结构上工作，我按下按钮查看更改。问题是在视图3中有一个组合框xaml：
< ComboBox ItemsSource = " {Binding ProjectsBrowserAxmModules}" SelectedValuePath = " AxmModuleId" DisplayMemberPath = " AxmModuleName"
SelectedValue = " {Binding SelectedAxmModule，UpdateSourceTrigger = PropertyChanged，Mode = TwoWay}"
控件：TextBoxHelper 。 水印 = " {Binding BrowserComboBoxWatermark}" 高度 = " 2" IsSynchronizedWithCurrentItem = " True" /> 这是绑定到属性的：
private int ？ selectedAxmModule ;
public int ？ SelectedAxmModule
{
get => selectedAxmModule ;
set
{
selectedAxmModule = value ;
OnPropertyChanged （）;
GetCurrentsModule （）; //在组合框中选择值后，此方法会在视图中进行午餐和更新列表。
}
} 现在一切正常，当我使用组合框对mu视图进行操作时，但是当我使用左边的按钮移动到其他视图时，我感觉很怪异，看起来所选项目上的属性正在储存。例如从我的组合框视图i
移动到视图1然后查看2并查看1然后列表并选择值，此属性将设置（ans午餐方法）这么多次，因为我改变了我的视图，我找不到原因。我怀疑它可能是我的命令实现
看起来像：
public class 命令 ： ICommand
{
private readonly 操作 < object> 执行 ;
private readonly 谓词 <对象> canExecute ;
public 命令 （ < span class ="typ">操作 < object> 执行 ， 谓词 < object> canExecute = null ）
{
此 。 执行 = 执行 ;
this 。 canExecute = canExecute ;
}
public bool CanExecute （ object 参数 ）
{
返回 此 。 canExecute == null || （ 此 。 canExecute ！= null && ; 此 。 canExecute （ 参数 ））;
}
public void 执行 （ object 参数 ）
{
此 。 执行 （ 参数 ）;
}
public 事件 EventHandler CanExecuteChanged
{ < span class ="pln">
add => CommandManager 。 RequerySuggested + = value ;
remove => CommandManager 。 RequerySuggested - = 值 ;
}
} 但不确定，有没有人有类似的经历？
我找到了答案，它看起来像每个视图渲染一些控件事件都堆叠起来，所以我在xaml中删除了绑定它与事件和：
private void ComboBox_CurrentBrowserAxmChanged（对象 发件人， RoutedEventArgs e）
{
< span style ="color：blue"> var combo = （ ComboBox ）发件人;
; if （combo ！= null & & combo.IsDropDownOpen）
{
（（ CurrentsHistoryViewModel ）DataContext）.GetCurrentsModuleCommand.Execute（sender）;
combo.IsDropDownOpen = < span style ="color：blue"> false ;
}
}
I have an unusual problem, let us say i have an application that main winow would look like:
Now as you see i have window split into two section one navigation with buttons that change view, other where view is displayed, using Mvvm in MainWindowsView model it looks like xaml:
<StackPanel DockPanel.Dock="Top">
<Button Content="View 1" Command="{Binding View1ViewModel}"/>
<Button Content="View 2" Command="{Binding View2ViewModel}" />
<Button Content="View 3 w combobox" Command="{Binding ListComboboxViewModel}" />
</StackPanel>
<Grid>
<ContentControl Grid.Row="0" DataContext="{Binding ContentControlDataContext}" Content="{Binding}" />
</Grid>View model:
private readonly View1ViewModel view1ViewModel;
private readonly View2ViewModel view2ViewModel;
private readonly ListComboboxViewModel listComboboxViewModel ;
public ICommand SetView1ViewModel { get; set; }
public ICommand SetView2ViewModel { get; set; }
public ICommand SetListComboboxViewModel{ get; set; }
public object ContentControlDataContext
{
get => this.contentControlDataContext;
set
{
this.contentControlDataContext = value;
OnPropertyChanged();
}
}
public MainViewModel()
{
this.view1ViewModel= new View1ViewModel();
this.view2ViewModel= new View2ViewModel();
this.listComboboxViewModel= new ListComboboxViewModel();
this.SetView1ViewModel = new Command(p => ContentControlDataContext = this.view1ViewModel);
this.View2ViewModel = new Command(p => ContentControlDataContext = this.view2ViewModel);
this.SetListComboboxViewModel= new Command(p => ContentControlDataContext = this.listComboboxViewModel);
}And basically everything works on this construction, I press button view changes. Problem is with view 3 there is a combobox there xaml:
<ComboBox ItemsSource="{Binding ProjectsBrowserAxmModules}" SelectedValuePath="AxmModuleId" DisplayMemberPath="AxmModuleName"
SelectedValue="{Binding SelectedAxmModule, UpdateSourceTrigger=PropertyChanged, Mode=TwoWay}"
controls:TextBoxHelper.Watermark="{Binding BrowserComboBoxWatermark}" Height="2" IsSynchronizedWithCurrentItem="True" />And this is binded to a property:
private int? selectedAxmModule;
public int? SelectedAxmModule
{
get => selectedAxmModule;
set
{
selectedAxmModule = value;
OnPropertyChanged();
GetCurrentsModule(); //after selecting value in combobox this method lunches and updates list in view.
}
}Now everything works fine when i do operation on mu view with combobox, but when i move to other view using buttons on the left I am getting weird situation, it looks like that property on selected item is stocking up. for example from my combobox view i move to view 1 then to view 2 and to view 1 back then to list and select value, this property will set (ans lunch method as well) so many times as i changed my view, and i can not find reason why. I have a suspicion it might be something with my command implementation that looks like:
public class Command : ICommand
{
private readonly Action<object> execute;
private readonly Predicate<object> canExecute;
public Command(Action<object> execute, Predicate<object> canExecute = null)
{
this.execute = execute;
this.canExecute = canExecute;
}
public bool CanExecute(object parameter)
{
return this.canExecute == null || (this.canExecute != null && this.canExecute(parameter));
}
public void Execute(object parameter)
{
this.execute(parameter);
}
public event EventHandler CanExecuteChanged
{
add => CommandManager.RequerySuggested += value;
remove => CommandManager.RequerySuggested -= value;
}
}But not sure, anyone had similar experience??
I found the answer, it looks like on every view rendering for some controls events are stack up, so i removed binding in xaml replaced it with event and :
private void ComboBox_CurrentBrowserAxmChanged(object sender, RoutedEventArgs e) { var combo = (ComboBox)sender; if (combo != null && combo.IsDropDownOpen) { ((CurrentsHistoryViewModel)DataContext).GetCurrentsModuleCommand.Execute(sender); combo.IsDropDownOpen = false; } }
这篇关于堆叠组合框选定的项目属性执行的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！
