无法在 C# 中以编程方式更改数据网格视图单元格的显示值

Question

I try to set the value of cell in my Data Grid View manually by code, however, when running there are nothing change. I print the value of these cell to console and the cells ' value are set, but they're not display.

        `TheLoaiList = BUSTheLoai.Instance.GetAllTheLoai();
        TheLoaiGrid.DataSource = TheLoaiList;
        int i = 0;
        foreach (DataGridViewRow row in TheLoaiGrid.Rows)
        {
            row.Cells["SoTuaSach"].Value = "10";
            Console.WriteLine(row.Cells["SoTuaSach"].Value);
            i++;
        }`

Answer 1

Your code seems to be on the right track. Binding the TheLoaiGrid.DataSource to the TheLoaiList that's good because you can change what's in the DataGridView by changing TheLoaiList . The next step you might want to try is making the items in the list work the same way (using binding) so that when you do your loop, you can modify the data not the DataGridViewRow :

foreach (TheLoai theLoai in TheLoaiList)
{
    theLoai.SoTuaSach = "10"; 
}

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For this to work, it requires a small change to the class that represents your row items. Suppose you defined TheLoaiList this way:

BindingList<TheLoai> TheLoaiList { get; } = new BindingList<TheLoai>();

Then here's an example of how to automatically notify the DataGridView when a property changes using INotifyPropertyChanged :

// using System.Runtime.CompilerServices;
class TheLoai : INotifyPropertyChanged
{
    string _soTuaSach = string.Empty;
    public string SoTuaSach
    {
        get => _soTuaSach;
        set
        {
            if (!Equals(_soTuaSach, value))
            {
                _soTuaSach = value;
                OnPropertyChanged();
            }
        }
    }
    string _column2 = string.Empty;
    public string Column2
    {
        get => _column2;
        set
        {
            if (!Equals(_column2, value))
            {
                _column2 = value;
                OnPropertyChanged();
            }
        }
    }
    public event PropertyChangedEventHandler PropertyChanged;
    protected virtual void OnPropertyChanged([CallerMemberName] string propertyName = null)
    {
        PropertyChanged?.Invoke(this, new PropertyChangedEventArgs(propertyName));
    }
}

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Here's a minimal working sample if you want to try this out.