Question

我有ListBox我绑定到视图模型中的ObservableCollection<Series>。每次用户单击“删除”按钮时，Delete类中的DelegateCommand Series将在ObservableCollection<Series>类中执行，该项目将从数据库中删除。

我正在寻找一些更新<ListBox ItemsSource="{Binding SeriesCollection}" Name="lbSeries" Background="#6E7587" ItemContainerStyle="{StaticResource highlightStyle}" SelectionMode="Single" AlternationCount="2" Grid.Row="2" ScrollViewer.VerticalScrollBarVisibility="Auto"> <ListBox.ItemTemplate> <DataTemplate> <Grid> <Grid.ColumnDefinitions> <ColumnDefinition Width="200" /> <ColumnDefinition Width="100" /> <ColumnDefinition Width="100" /> <ColumnDefinition Width="100" /> <ColumnDefinition Width="100" /> <ColumnDefinition Width="*" /> </Grid.ColumnDefinitions> <TextBox Margin="5,0" FontSize="14" Name="txtName" Text="{Binding Name}" Width="190" Height="30" Grid.Column="0" /> <wpfToolkit:IntegerUpDown Value="{Binding Season}" Name="nudSeason" FontSize="14" Height="30" Width="95" Increment="1" Maximum="100000" Minimum="0" Grid.Column="1" /> <wpfToolkit:IntegerUpDown Value="{Binding Episode}" Name="nudEpisode" FontSize="14" Height="30" Width="95" Increment="1" Maximum="100000" Minimum="0" Grid.Column="2" /> <Button Command="{Binding Save}" Grid.Column="3" Width="60" Height="50" Cursor="Hand" ToolTip="Save program" VerticalAlignment="Center" HorizontalAlignment="Center"> <Button.Template> <ControlTemplate> <Border HorizontalAlignment="Center" VerticalAlignment="Center" > <Image Source="Resources\Save.png" Width="30" Height="40" /> </Border> </ControlTemplate> </Button.Template> </Button> <Button Command="{Binding Delete}" Grid.Column="4" Width="60" Height="50" Cursor="Hand" CommandParameter="{Binding ElementName=lbSeries,Path=SelectedItem}" ToolTip="Remove program" VerticalAlignment="Top" HorizontalAlignment="Left" Margin="15,0"> <Button.Template> <ControlTemplate> <Border HorizontalAlignment="Center" VerticalAlignment="Center" > <Image Source="Resources\Delete.png" Width="30" Height="40" /> </Border> </ControlTemplate> </Button.Template> </Button> <Label Content="{Binding Information}" Grid.Column="5" FontSize="14" Margin="10,0" /> </Grid> </DataTemplate> </ListBox.ItemTemplate> </ListBox>的方法，以便在删除XAML视图时立即删除相关项目。

目前这种情况并没有发生，我对WPF相对较新，并且一直试图让这个工作好几天，请告诉我哪里出错：

相关XAML：

using System;
using System.Collections.ObjectModel;
using System.ComponentModel;
using System.Data;
using SeriesTracker.Functions;
using System.Linq;

namespace SeriesTracker.Client
{
    public class SeriesTrackerViewModel : INotifyPropertyChanged
    {
        public DelegateCommand NewSeries { get; set; }

        public event PropertyChangedEventHandler PropertyChanged;

        private ObservableCollection<Series> _series = new ObservableCollection<Series>();
        public ObservableCollection<Series> SeriesCollection
        {
            get { return _series; }
            set
            {
                _series = value;
                RaisePropertyChanged("SeriesCollection");
            }
        }

        public SeriesTrackerViewModel()
        {
            NewSeries = new DelegateCommand(AddNewSeries);

            DataTable table = DataAccessLayer.GetSeries();
            if (table.Rows.Count > 0)
                LoadSeries(table);
        }

        private void LoadSeries(DataTable table)
        {
            foreach (DataRow row in table.Rows)
            {
                int id = Int32.Parse(row["Id"].ToString());
                string name = row["Name"].ToString();

                int season = 0;
                int episode = 0;

                if (Int32.TryParse(row["Season"].ToString(), out season) &&
                    Int32.TryParse(row["Episode"].ToString(), out episode))
                {
                    var series = new Series(id, name, season, episode);
                    SeriesCollection.Add(series);
                }
            }
        }

        public void AddNewSeries()
        {
            SeriesCollection.AddSeries();
        }

        private void RaisePropertyChanged(string propertyName)
        {
            PropertyChangedEventHandler handler = PropertyChanged;
            if (handler != null)
                handler(this, new PropertyChangedEventArgs(propertyName));
        }
    }
}

查看型号：

using System;
using System.ComponentModel;
using System.Collections.ObjectModel;

namespace SeriesTracker.Functions
{
    public class Series : INotifyPropertyChanged
    {
        public event PropertyChangedEventHandler PropertyChanged;

        private DelegateCommand _save;
        public DelegateCommand Save 
        {
            get { return _save; }
            set
            {
                _save = value;
                RaisePropertyChanged("Save");
            }
        }

        private DelegateCommand _delete;
        public DelegateCommand Delete 
        { 
            get{return _delete;}
            set
            {
                _delete = value;
                RaisePropertyChanged("Delete");
            }
        }

        public int Id { get; set; }

        string _name;
        public String Name
        {
            get { return _name; } 
            set
            {
                _name = value;
                RaisePropertyChanged("Name");
            }
        }

        int _season;
        public Int32 Season 
        {
            get { return _season; } 
            set
            {
                _season = value;
                RaisePropertyChanged("Season");
            }
        }

        int _episode;
        public Int32 Episode 
        {
            get { return _episode; }
            set
            {
                _episode = value;
                RaisePropertyChanged("Episode");
            }
        }

        string _information;
        public String Information 
        {
            get { return _information; }
            set
            {
                _information = value;
                RaisePropertyChanged("Information");
            }
        }

        public Series(int id,string name,int season, int episode)
        {
            Id = id;
            Name = name;
            Season = season;
            Episode = episode;

            Save = new DelegateCommand(SaveItem);
            Delete = new DelegateCommand(DeleteItem);
        }

        public void DeleteItem()
        {
            var selectedItem = this;
            if (selectedItem.Id != -1)
            {
                DataAccessLayer.Delete(selectedItem.Id);
            }
        }

        public void SaveItem()
        {
            var selectedItem = this;
            if (selectedItem.Id == -1)
                DataAccessLayer.AddEntry(selectedItem.Name,selectedItem.Season,selectedItem.Episode);
            else
                DataAccessLayer.Update(selectedItem.Id,
                    selectedItem.Name,selectedItem.Season,selectedItem.Episode);
        }

        private void RaisePropertyChanged(string propertyName)
        {
            PropertyChangedEventHandler handler = PropertyChanged;
            if (handler != null)
                handler(this, new PropertyChangedEventArgs(propertyName));
        }
    }
}

系列课程：

{{1}}

Answer 1

你不应该在Series类中保留DeleteCommand，它应该在视图模型上。

在视图模型中，您可以轻松更新ObservableCollection。

您需要在ViewModel和XAML上使用Type Series的Generic delegate命令，您需要在命令Parameter上传递{Binding}。

查看型号C＃： -

DelegateCommand<Series> DeleteCommand { get; set; } 
DeleteCommand = new RelayCommand<Series>(OnDelete); 

// This method will gets execute on click the of Delete Button1
private void OnDelete(Series series) 
{
}

XAML： - 在“删除”按钮上，更改绑定和命令参数值

CommandParameter =“{Binding}”
Command =“{Binding DataContext.DeleteCommand，RelativeSource = {RelativeSource Mode = FindAncestor，AncestorType = {x：Type Window}}}“

希望这会对你有所帮助

Answer 2

您可以在[{1}}中订阅每个系列的PropertyChangedEventHandler，然后在事件触发时调用ObservableCollection

更新：我的意思是：

RaisePropertyChanged("SeriesCollection")

当T中的属性更改时，刷新ObservableCollection <t> - WPF MVVM </t>

2 个答案: