DataGridView的绑定列表在我每次单击保存时均不显示任何内容并清除对象

Question

我正在尝试将类列表绑定到WinForms应用程序上的DataGridView。当前，绑定代码不执行任何操作。我已经调试通过，并且源代码正确，其中包含带有正确项目的列表。但我在DataGridView中看不到行。

如何将列表中的内容显示到DataGridView上？此外，当前每次单击“保存”都会清除我的类对象，但是我想保留之前在构造函数中输入的值。如果已经存在一个国家/地区，我希望用户弹出框指出他们是否要重写此文字-这有可能吗/如何才能最好地做到这一点？

CountryWithDates.cs

 class CountryWithDates
{
    public string country;
    public DateTime firstDate;
    public DateTime furtherDate;
    public DateTime rolldownDate;
    public DateTime endDate;
}

在保存时单击：

  private void Save_Click(object sender, EventArgs e)
    {

        List<CountryWithDates> countryDates = new List<CountryWithDates>();

        for (int i = 0; i < Countries_LB.Items.Count; i++)
        {
            if (Countries_LB.GetItemChecked(i))
            {         
                countryDates.Add(new CountryWithDates(){country = Countries_LB.Items[i].ToString(),
                    firstMarkdownDate = DateTime.Parse(firstDatePicker.Text),
                    furtherMarkdownDate = DateTime.Parse(furtherDatePicker.Text),
                    rolldownMarkdownDate = DateTime.Parse(rolldownDatePicker.Text),
                    endMarkdownDate = DateTime.Parse(endMarkdownPicker.Text)});
            }

        }


//THIS DOESNT DO ANYTHING - I WANT TO BIND THE SOURCE TO THE GRIDVIEW but i dont see the output in the data gridview on the form when i click save
            var bindingList = new BindingList<CountryWithDates>(countryDates);
            var source = new BindingSource(bindingList, null);
            gv_Countries.DataSource = source;

        }

Answer 1

您应该在课堂上创建公共Porperties，而不是公共Fields >>：

class CountryWithDates
{
    //Following the naming rule is good. I'll leave it to you.
    public string country { get; set; }
    public DateTime firstDate { get; set; }
    public DateTime furtherDate { get; set; }
    public DateTime rolldownDate { get; set; }
    public DateTime endDate { get; set; }

    public CountryWithDates() { }

    public override string ToString()
    {
        return country;
    }
}
通过这种方式，您可以将CountryWithDates对象的列表绑定到CheckedListBox：

var lst = new List<CountryWithDates>();

//Add new objects ...
//lst.Add(new CountryWithDates { country = "Country 1", firstDate ... });

checkedListBox1.DataSource = null;
checkedListBox1.DataSource = lst;
要从列表中获取并更新选中的项目，创建一个新的BindingSource，并将其绑定到DataGridView，您只需执行以下操作：

checkedListBox1.CheckedItems
    .Cast<CountryWithDates>()
    .ToList()
    .ForEach(item =>
    {
        item.firstDate = firstDatePicker.Value;
        item.furtherDate = furtherDatePicker.Value;
        item.rolldownDate = rolldownDatePicker.Value;
        item.endDate = endMarkdownPicker.Value;
    });
dataGridView1.DataSource = null;
var bs = new BindingSource(checkedListBox1.CheckedItems.Cast<CountryWithDates>(), null);
dataGridView1.DataSource = bs;

Answer 2

如果我这样做，我会：