C# WPF MVVM - 将多个 csv 合并到数据网格

Question

我一直在研究这个小程序，它需要获取 CSV 文件的文件输入，将它们存储在列表框中，然后自动更新数据网格。当添加更多文件时，数据网格需要用新的文件数据扩展并添加到它旁边。

有效的方法是使用 XAML 代码和代码隐藏中的绑定(bind)将文件添加到列表框。

不起作用的是合并数据以动态显示与数据网格的绑定(bind)。属性发生了变化，但网格没有更新。

在 DataGridViewModel 中是我的 csv 合并代码所在的位置:

public class DataGridViewModel 
    {
   static public DataGridModel _dataGridModel = new DataGridModel();

    public static void ReturnDataTableForGridView()
    {
        DataTable mainTable = new DataTable();
        //-- #3 Test merge 
        foreach (var item in SidePanelViewModel.GetPathFileList())
        {
            DataTable dataTable = new DataTable();
            try
            {

                string[] Lines = File.ReadAllLines(item.Filepath);
                string[] Fields;
                Fields = Lines[0].Split(new char[] { ';' });
                int Cols = Fields.GetLength(0);

                //1st row skal være kolonne navn; 
                for (int X = 0; X < Cols; X++)
                    dataTable.Columns.Add(Fields[X].ToLower(), typeof(string));

                DataRow Row;
                for (int T = 1; T < Lines.GetLength(0); T++)
                {
                    Fields = Lines[T].Split(new char[] { ';' });
                    Row = dataTable.NewRow();
                    for (int f = 0; f < Cols; f++)
                        Row[f] = Fields[f];
                    dataTable.Rows.Add(Row);
                }
                //-- Merges every files(tables) into one.
                mainTable.Merge(dataTable);                   
            }
            catch (Exception)
            {
                return null;
            }
        }
        //-- Sets the datatablemerger which raises the propertychanged 
        _dataGridModel.DatatableMerger = mainTable;

    }
}

数据网格模型类

   public class DataGridModel : INotifyPropertyChanged
{


    DataTable _dataTableMerger { get; set; } = new DataTable();

    public DataTable DatatableMerger
    {
        get
        {
            return _dataTableMerger;
        }
        set
        {
            _dataTableMerger = value;
            OnPropertychanged("DatatableMerger");
        }
    } 


    public event PropertyChangedEventHandler PropertyChanged;
    public void OnPropertychanged([CallerMemberName] string caller = "")
    {
        PropertyChanged?.Invoke(this, new PropertyChangedEventArgs(caller));
    }

}

数据 GridView 类

    public DataGridView()
    {
        InitializeComponent();
    }

XAML 代码:

        <DataGrid x:Name="MainDataGrid"  Grid.Row="1" VerticalAlignment="Stretch" Height="auto" ItemsSource="{Binding Path=DatatableMerger, Mode=TwoWay, UpdateSourceTrigger=PropertyChanged, NotifyOnSourceUpdated=True}" >
    </DataGrid>
</Grid>
<UserControl.DataContext>
     <Model:DataGridModel/>
</UserControl.DataContext>

当前输出:



期望输出:



Propertychanged getting raised

Answer 1

我的 friend 帮我举了一个例子。
继安斯瓦尔之后:
XAML 中的 DataContext 是错误的。您的 View 必须与您的 ViewModel 而不是您的模型进行通信。
如果您运行 MVVM，那么在 Views 代码隐藏中使用按钮单击事件是错误的。它必须在 ViewModel 中完成。
除此之外，您的 CSV 解析器是错误的实现。只要字段包含分号、新行或 komma 用作字段分隔符而不是分号，它将立即中断。
阅读更多关于 CSV 文件的 RFC 规范 HERE或使用可以正确解析文件的库。前任。 ExcelDataReader如果你想把它放到你的数据表中； ExcelDataReader.DataSet
关于功能和正确绑定(bind)的示例，请遵循以下示例:
主窗口.cs

public partial class MainWindow : Window
{
    public MainWindow()
    {
        InitializeComponent();
    }
}

XAML

    <Window.DataContext>
    <local:DataGridViewModel/>
</Window.DataContext>
<Grid>
    <DataGrid Margin="0,0,0,35" ItemsSource="{Binding DatatableMerger}"/>
    <Button Content="Add rows" Margin="0,0,10,10" Command="{Binding AddRowsButtonClickCommand}" Height="20" VerticalAlignment="Bottom" HorizontalAlignment="Right" Width="75"/>
</Grid>

DataGridModel.cs

    public class DataGridModel
{
    public DataTable DatatableMerger { get; set; }
}

DataGridViewModel.cs

    public class DataGridViewModel : INotifyPropertyChanged
{
    private readonly DataGridModel _dataGridModel = new DataGridModel();

    public DataTable DatatableMerger => _dataGridModel.DatatableMerger;

    public ICommand AddRowsButtonClickCommand => new DelegateCommand(o => ReturnDataTableForGridView());

    public event PropertyChangedEventHandler PropertyChanged;

    private void OnPropertyChanged(string propertyName) => PropertyChanged?.Invoke(this, new PropertyChangedEventArgs(propertyName));

    public void ReturnDataTableForGridView()
    {
        var dt = new DataTable();

        dt.Columns.Add("Foo");
        dt.Columns.Add("Bar");
        dt.Columns.Add("Baz");

        for (var i = 0; i < 5; i++)
            dt.Rows.Add($"Value {i}", i, DateTime.Now.AddSeconds(i));

        _dataGridModel.DatatableMerger = dt;
        OnPropertyChanged(nameof(DatatableMerger));
    }
}

委托(delegate)人命令

    public class DelegateCommand : ICommand
{
    private readonly Predicate<object> _canExecute;
    private readonly Action<object> _execute;

    public event EventHandler CanExecuteChanged;

    public DelegateCommand(Action<object> execute) : this(execute, null) { }

    public DelegateCommand(Action<object> execute, Predicate<object> canExecute)
    {
        _execute = execute;
        _canExecute = canExecute;
    }

    public bool CanExecute(object parameter)
    {
        if (_canExecute is null)
            return true;

        return _canExecute(parameter);
    }

    public void Execute(object parameter)
    {
        _execute(parameter);
    }

    public void RaiseCanExecuteChanged()
    {
        CanExecuteChanged?.Invoke(this, EventArgs.Empty);
    }
}

对于合并功能。使用 YourMainTableName = Mergetables(Table1, table2); 调用函数

        public DataTable MergeTables(DataTable Table1, DataTable Table2)
    {
        DataTable Mergetable = new DataTable();

        foreach (DataColumn d in Table1.Columns)
        {
            Mergetable.Columns.Add(d.ColumnName);
        }

        foreach (DataColumn d in Table2.Columns)
        {
            Mergetable.Columns.Add(d.ColumnName);
        }

        int Table1Cols = Table1.Columns.Count;
        int Table1Rows = Table1.Rows.Count;
        int Table2Cols = Table2.Columns.Count;
        int Table2Rows = Table2.Rows.Count;

        DataRow row2;
        bool end = false;
        int RowCount = 0;

        while (!end)
        {
            end = true;
            if (RowCount < Table1Rows || RowCount < Table2Rows)
            {
                end = false;
                row2 = Mergetable.NewRow();

                if (RowCount < Table1Rows)
                {
                    for (int col = 0; col < Table1Cols; col++)
                    {
                        row2[col] = Table1.Rows[RowCount][col];
                    }
                }

                if (RowCount < Table2Rows)
                {
                    for (int col = 0; col < Table2Cols; col++)
                    {
                        row2[col + Table1Cols] = Table2.Rows[RowCount][col];
                    }
                }
                Mergetable.Rows.Add(row2);
            }
            RowCount++;
        }
        return Mergetable;
    }