如何在我的情况下使用mvvm (ObservableCollection in ObservableCollection)绑定ObservableCollection

Question

我所处的情况是“ObservableCollection of”"tablegenerateModel“类进一步包含"column_Data”类的ObservableCollection，而"column_Data“类包含三个必须绑定到包含三列的DataGrid的UI元素。您可以复制粘贴我的代码，如果您愿意的话，我已经为您编写了所有的类和xaml，以验证我的代码，所以我的Model.cs如下所示：

  public class tablegenerateModel {

    public ObservableCollection < column_Data > Column_data_List {
        get;
        set;
    }
    public int NumberOfColumns {
        get;
        set;
    }

    private ICommand _CreatColumnCommand; //THIS IS THE BUTTON EVENT GENERATED WHEN USER PRESS AN INTEGER VALUE IN "NumberOfColumns" AND PRESS "Create" button. So the "Column_data_List" will repeat that many times the value user entered
    ViewModel vm;
    public ICommand CreatColumnCommand {
        get {
            if (_CreatColumnCommand == null) {
                _CreatColumnCommand = new RelayCommand(
                    param => vm = new ViewModel(this)
                );
            }
            return _CreatColumnCommand;
        }
    }
}
public class column_Data {
    public string Column_Name {
        get;
        set;
    }
}

我的视图模型是：

   public class ViewModel: INotifyPropertyChanged {
    private ObservableCollection < tablegenerateModel > _lb_GlobalList;
    private ObservableCollection < column_Data > _Column_data_List;

    public ObservableCollection < tablegenerateModel > lb_GlobalList {
        get {
            return _lb_GlobalList;
        }
        set {
            if (value != _lb_GlobalList) {
                _lb_GlobalList = value;
                RaisePropertyChanged("lb_GlobalList");
            }
        }
    }

    public ObservableCollection < column_Data > Column_data_List {
        get {
            return _Column_data_List;
        }
        set {
            if (value != _Column_data_List) {
                _Column_data_List = value;
                RaisePropertyChanged("Column_data_List");
            }
        }
    }

    public ICommand ClickCommand

    private bool _canExecute;
    public ViewModel() {
        _canExecute = true;
        lb_GlobalList = new ObservableCollection < tablegenerateModel > ();
        for (int i = 1; i < 6; i++) {
            //Add To it data here
        }
    }

    public ViewModel(tablegenerateModel tablegenerateModels) //IT WILL BE CALLED WHEN BUTTON WILL BE CLICKED (see tablegenerateModel class ICommand for it)
        {
            Column_data_List = new ObservableCollection < column_Data > ();
            for (int i = 1; i < tablegenerateModels.NumberOfColumns; i++) { //Add data here
            }
            MessageBox.Show("The NumberOfColumns value is:" + tablegenerateModels.NumberOfColumns);
        }

}
}

意见是：

 <Window x:Class="PyXgen.MainWindow" xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation" xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml" xmlns:vM="clr-namespace:PyXgen" Title="MainWindow" Height="350" Width="525">
    <Window.DataContext>
        <vM:ViewModel></vM:ViewModel>
    </Window.DataContext>
    <Grid Name="ButtonsContainer">


        <ListBox Grid.Row="1" ItemsSource="{Binding lb_GlobalList}" ScrollViewer.VerticalScrollBarVisibility="Auto" BorderBrush="Gray" Margin="0,30,0,0" Grid.RowSpan="2">
            <ListBox.ItemTemplate>
                <DataTemplate>
                    <Grid>
                        <StackPanel>
                            <Grid Margin="0,2">
                                <Grid.ColumnDefinitions>
                                    <ColumnDefinition Width="*" />
                                    <ColumnDefinition Width="*" />
                                </Grid.ColumnDefinitions>
                                <Grid.RowDefinitions>
                                    <RowDefinition Height="45" />
                                    <RowDefinition Height="45" />
                                    <RowDefinition Height="45" />
                                    <RowDefinition Height="*" />
                                    <RowDefinition Height="*" />
                                    <RowDefinition Height="*" />
                                </Grid.RowDefinitions>

                                <Grid Grid.Row="4">
                                    <StackPanel>
                                        <Grid Margin="0,2">


                                            Grid.Row="0" Width="80px" Height="20px" Margin="20,5,0,0" Name="fname4"/>
                                            <Button Grid.Row="1" Grid.Column="1" Height="25" Width="70" Content="Create" Command="{Binding CreatColumnCommand}" HorizontalAlignment="Center" VerticalAlignment="Center"></Button>
                                        </Grid>
                                    </StackPanel>
                                </Grid>
                                <Grid Margin="0,2" Grid.Row="5">
                                    <DataGrid x:Name="gvSelectedCourses" Grid.Column="1" HorizontalAlignment="Center" ItemsSource="{Binding Column_data_List , Mode=TwoWay}" AutoGenerateColumns="False" Width="450">
                                        <DataGrid.Columns>
                                            <DataGridTextColumn Header="Column Name" Binding="{Binding  ,Mode=TwoWay}" Width="150" />
                                        </DataGrid.Columns>
                                    </DataGrid>
                                </Grid>
                            </Grid>
                        </StackPanel>
                    </Grid>
                </DataTemplate>
            </ListBox.ItemTemplate>
        </ListBox>
    </Grid>
</Window>

单击"_CreatColumnCommand“按钮(在tableGenerateModel类中)将调用传递"this”对象的ViewModel构造器，以获取输入的整数值，以重复输入的整数值的DataGrid行数(该整数值被输入到同一类的"NumberOfColumns“文本框中)。

现在的问题是如何绑定"_Column_data_List“，以便它将添加和更新DataGrid的行(通过用户在textbox中输入的整数值)。

当前，当我在文本框中输入整数值并单击"create“按钮时，将使用ViewModel弹出窗口调用MessageBox构造器。

 MessageBox.Show("The NumberOfColumns value is:" + tablegenerateModels.NumberOfColumns);

如何将此"_Column_data_List“绑定到这样的位置:它将添加或更新DataGrid的行(通过用户在textbox中输入的intger值，在上面的快照中)。

有人能帮我吗?

Answer 1

按以下方式更新代码。您已经在tablegeneratedModel中绑定了可观察的集合，但是您正在更新ViewModel上的一个集合。

public ViewModel(tablegenerateModel tablegenerateModels) //IT WILL BE CALLED WHEN BUTTON WILL BE CLICKED (see tablegenerateModel class ICommand for it)
        {
            tablegenerateModels.Column_data_List = new ObservableCollection<column_Data>();
            for (int i = 1; i < tablegenerateModels.NumberOfColumns; i++)
            {
                Column_data_List.Add(lb_col = new column_Data()
                {
                    Column_Name = "ColumnName" + i,
                    Data_Size = i,
                    Data_types = "Double" + i
                });
            }           
            MessageBox.Show("The NumberOfColumns value is:" + tablegenerateModels.NumberOfColumns);
        }

Answer 2

“CreatColumnCommand”拼写错误，但一直如此，所以这不是您的问题。但是你的“CreatColumnCommand`”不是在视图模型中，而是在模型中，这是问题所在吗？

Answer 3

在给定的情况下，我必须在ObservableCollection中有ObservableCollection，但是如果您看到我的ViewModel，我将尝试添加到ViewModel中的Column_data_List中，而我应该在模型本身中添加它(因为视图不能同时处理lb_GlobalList和Column_data_List)。我做了这件事对我来说很管用。