c# - 迭代 ObservableCollection<t>价值观</t>

问题描述

我正在尝试创建一个库，用于从可观察的集合在 WPF 中创建报告，但我不知道如何循环ObservableCollection将值写入FlowDocument表中。我尝试将通用集合转换为 a IEnumerable，但我不断得到

抛出异常：'System.NullReferenceException'

目标是编写一个可以接受所有ObservableCollection类型的库，所以我编写了这个类（片段）：

public class Report_Definition<T> : INotifyPropertyChanged
{
        public Report_Definition(FlowDocument doc, ObservableCollection<T> data)
        {
            Fill_data(data, doc);
        }

        private void Fill_data(ObservableCollection<T> data, FlowDocument doc)
        {
            //I only take 25 records from ObservableCollection - to create more Tables
            for (int i = 0; i < data.Count; i += 25)
            {
                var list = (from c in data select c).Skip(i).Take(25);

                 if (i < 25) //Test for only first Table
                {
                    for (int row = 0; row < list.Count(); row++)
                    {
                        TableRow my_cell = new TableRow();

                        foreach (var item in list)
                        {
                            foreach (var w in item as IEnumerable<T>) //ERROR HERE !!!
                            {
                                my_cell.Cells.Add(new TableCell(new Paragraph(new Run(w.ToString()))) { Padding = new Thickness(2), BorderBrush = Brushes.Black, BorderThickness = new Thickness(0.7) });
                            }

                        }

                        TableRowGroup whole_row = new TableRowGroup();
                        whole_row.Rows.Add(my_cell);
                        My_table.RowGroups.Add(whole_row); //I get reference of this elsewhere...
                    }
                }
        }
}

这是我的Employee课：

public class Employee : INotifyPropertyChanged
{
        public string Name { get; set; }
        public string Surname { get; set; }
        public string Address { get; set; }
        public string Country { get; set; }

        #region INotifyPropertyChanged

        public event PropertyChangedEventHandler PropertyChanged;
        private void OnPropertyChanged(string propertyName)
        {
            PropertyChanged?.Invoke(this, new PropertyChangedEventArgs(propertyName));
        }

        #endregion
}

因此，在大写中我使用ObservableCollection(Employee)，并且我想遍历Employee此集合中的每个以在表行中写入值。

目前此代码仅将类型写入单元格，例如My_Project.Model.Employee.

有人可以告诉我如何正确地做到这一点吗？

PS：如您所见，我正在遵循 MVVM 方法。

标签： c#wpfobservablecollectionflowdocumentgeneric-collections

假设这是您拥有的课程

public class Employee
{
    public string Name { get; set; }
    public string Surname { get; set; }
    public string Address { get; set; }
    public string Country { get; set; }
}

下面的代码将产生以下输出

    var props = typeof(Employee).GetProperties();

    var employee = new Employee { Name = "Athul", Surname = "Raj", Address = "Blah", Country = "India" };

    foreach (var prop in props)
    {
        Console.WriteLine($"{prop.Name} = {prop.GetValue(employee)}");
    }

    Console.ReadKey();

Name = Athul
Surname = Raj
Address = Blah
Country = India

您可以在方法中使用 typeof(T).GetProperties() 而不是 typeof(Employee).GetProperties()

c# - 迭代 ObservableCollection价值观

问题描述

解决方案

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