迭代 ObservableCollection<T> 值

Question

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

Exception thrown: 'System.NullReferenceException'

目标是编写一个接受所有 ObservableCollection 类型的库，所以我写了这个 class（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 class :

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
}

所以在大写中我使用 ObservableCollection(Employee)，我想遍历此集合中的每个 Employee 以在 table 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执行此操作吗？

P.S.: 如你所见，我正在遵循 MVVM 方法。

Answer 1

假设这是 class 你有

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()

Answer 2

要获取属性并为新单元格添加值，这样的方法可能有效：

var props = item.GetType().GetProperties(BindingFlags.Public | BindingFlags.Instance);
foreach (var p in props) 
{
    my_cell.Cells.Add(new TableCell(new Paragraph(new Run(p.GetValue(this).ToString()))) { Padding = new Thickness(2), BorderBrush = Brushes.Black, BorderThickness = new Thickness(0.7) });
}

迭代 ObservableCollection<T> 值

Iterating over ObservableCollection<T> values

c#

wpf

observablecollection

flowdocument

generic-collections