Question

我的窗口中有一些文本框，点击btn_add后它们的内容将被添加到Observable Collection中，然后将成为dg_VoucherDetail的源。问题是：当我第一次使用它时一切都很好，但第二次它只是替换旧的Observable Collection，除了向旧的Collection添加新项目，对于编辑部分，Collection中没有要搜索和编辑的项目。这是代码：

assert_predicate flash[:error], :nil?

Answer 1

这是一个简单的片段，它会更新＆＃34;如果条目存在于集合中，则为条目。这个片段有硬编码的东西，但是使它变得动态应该是微不足道的。

using System.Linq;
using System.Windows;
using System.Windows.Controls;
using System.Collections.ObjectModel;

namespace UpdateObservableCollection_47291451
{
    /// <summary>
    /// Interaction logic for MainWindow.xaml
    /// </summary>
    public partial class MainWindow : Window
    {

        DataGrid dg = new DataGrid();
        Button btn = new Button();
        ObservableCollection<VoucherDetail> datasource = new ObservableCollection<VoucherDetail>();
        public MainWindow()
        {
            InitializeComponent();
            dg.Height = 200;
            dg.Width = 500;
            MainGrid.Children.Add(dg);//add DataGrid to page
            btn.Content = "Click me";
            btn.Click += Btn_Click;
            btn.Height = 25;
            btn.Width = 50;
            MainGrid.Children.Add(btn);//add button to page

            dg.ItemsSource = datasource;//bind grid to data

            //create initial data records
            for (int i = 0; i < 5; i++)
            {
                datasource.Add(new UpdateObservableCollection_47291451.VoucherDetail { Credit = i, Debit = i, DefinitiveID = i, LedgerID = i });
            }
        }

        private void Btn_Click(object sender, RoutedEventArgs e)
        {
            //if a record with DefinitiveID of 1 exist, then update the entry
            if (datasource.FirstOrDefault(p => p.DefinitiveID == 1) != null)
            {
                datasource.First(p => p.DefinitiveID == 1).Credit = 1234;
                dg.Items.Refresh();
            }
            else
            {
                datasource.Add(new UpdateObservableCollection_47291451.VoucherDetail { DefinitiveID = 99, Credit = 99, Debit = 99, LedgerID = 99 });
            }
        }
    }


    internal class VoucherDetail
    {
        public decimal LedgerID { get; set; }
        public decimal DefinitiveID { get; set; }
        public decimal Debit { get; set; }
        public decimal Credit { get; set; }
    }


}

Observable Collection编辑项目（如果存在），否则添加新项目

1 个答案: