I have a DataGridView and Checkbox column attached to it. I would like to achieve something like this, when a few checkboxes are selected, it will compare the cells value of column named Description between those selected row. If the values are not same, a message box will be show up, else the value will be parse into a textbox.

As in example above, a messagebox should be show up when those rows are selected.

This is what i have done so far and i don't know how to continue from here.

private void datagridview1_CellClick(object sender, DataGridViewCellEventArgs e)
        {
            foreach (DataGridViewRow r in datagridview1.Rows)
            {
                bool ckboxselected = !Convert.ToBoolean(r.Cells[0].Value);

                if (e.RowIndex >= 0 && e.ColumnIndex == 0)
                {
                    if (ckboxselected)
                    {
                        //compare
                    }
                    else
                    {
                        //another action
                    }
                }
            }
        }

I appreciate you help!

CodePudding user response：

From what you write, I think your code should look like something along the lines of this:

    private void datagridview1_CellClick(object sender, DataGridViewCellEventArgs e)
    {
        string description =null;
        bool differentDescriptionsChecked=false;
        foreach (DataGridViewRow r in datagridview1.Rows)
        {
            bool ckboxselected = Convert.ToBoolean(r.Cells[0].Value);
            if (ckboxselected)
            {
                 string description2 = Convert.ToString(r.Cells[2].Value);
                 if(description==null)
                 {
                      description=description2;
                 }
                 else if(description!=description2)
                 {
                      differentDescriptionsChecked=true;
                      break;
                 }
            }
        }
        if(description==null)
        {
              // show message "no row checked"
        }
        else if(differentDescriptionsChecked)
        {
             // show message "different descriptions checked"
        }
        else
        {
             // do something with "description"
        }
    }

Note I removed the if (e.RowIndex >= 0 && e.ColumnIndex == 0) from your code, it looked superfluous for me (but maybe I am missing something). Also in ckboxselected = !Convert.ToBoolean(r.Cells[0].Value); the "not" operator did not look right (decide by yourself if your original version was correct).

When the requirements become slightly more complicated, I would recommend to approach this in more than step: first, fill some collection like a list, hashset or dictionary with the content from the rows which you are interested in. Then, in a second step evaluate the content to make decisions from it. That could have been done here in this case, too.

CodePudding user response：

Another approach is to load the DataGridView using a class which means when performing assertions there is, in this case a call to commit changes of the DataGridViewCheckBoxColumn.

Sample model/class, where INotifyPropertyChanged notifies clients that a property value has changed.

public class Item : INotifyPropertyChanged
{
    private bool _selected;
    private string _description;



    public bool Selected
    {
        get => _selected;
        set
        {
            _selected = value;
            OnPropertyChanged();
        }
    }
    public int Id { get; set; }    
    public string Description
    {
        get => _description;
        set
        {
            _description = value; 
            OnPropertyChanged();
        }
    }

    public event PropertyChangedEventHandler PropertyChanged;

    protected virtual void OnPropertyChanged([CallerMemberName] string propertyName = null)
    {
        PropertyChanged?.Invoke(this, new PropertyChangedEventArgs(propertyName));
    }
}

Form code

public partial class Form1 : Form
{
    private readonly BindingSource _bindingSource = new BindingSource();
    private BindingList<Item> _bindingList;
    public Form1()
    {
        InitializeComponent();
        Shown  = OnShown;
    }
    
    private void OnShown(object sender, EventArgs e)
    {

        _bindingList = new BindingList<Item>(new List<Item>()
        {
            new Item() {Selected = false,Id = 1,Description = "A"},
            new Item() {Selected = false,Id = 2,Description = "B"},
            new Item() {Selected = false,Id = 3,Description = "B"},
            new Item() {Selected = false,Id = 4,Description = "A"},
        });

        _bindingSource.DataSource = _bindingList;
        dataGridView1.DataSource = _bindingSource;
        dataGridView1.Columns["Id"]!.ReadOnly = true;
        dataGridView1.CellContentClick  = DataGridView1OnCellContentClick;
    }

    private void DataGridView1OnCellContentClick(object sender, DataGridViewCellEventArgs e)
    {
        if (e.RowIndex < 0 || e.ColumnIndex != 0) return;

        dataGridView1.CommitEdit(DataGridViewDataErrorContexts.Commit);

        for (int index = 0; index < _bindingList.Count; index  )
        {
            if (_bindingList[index].Selected)
            {
                // TODO
            }
            else
            {
                // TODO
            }
        }
    }
}