How To Bind an Array/List's Elements To DataGridViewTextBoxColumn's - arrays

Question

In DataGridView, how to bind an array or list (with n elements) to n DataGridViewTextBoxColumn's?
Maybe it's not so clear, for example, I have a class:
public class DynamicNumberFieldsClass
{
public string FullName { get; set; }
public int[] Years { get; set; }
}
The expected form a DataGridView should display:
FullName Year1 Year2 Year3...
Peter 11 12 13
Bryan 21 22 23
If I have to use reflection, it's okay for me.
Any idea?
Thanks!
Peter
P.S.: We can assume the array field will never be null.
we can even assume that the number of elements in the array is fixed once a session is started, but the user can change it in Settings, so in the next session, the number of elements might not be the same.

Answer 1

I am assuming you are working in Windows Forms. I was able to at least display the data in the format you've shown by putting the DataGridView in Virtual Mode. You had best follow the entire walkthrough for a complete solution, but here is what I did in a quick test (hacked up from the samples in the walkthough):
CellValueNeeded handler:
private void dataGridView1_CellValueNeeded(object sender, DataGridViewCellValueEventArgs e)
{
// If this is the row for new records, no values are needed.
if (e.RowIndex == this.dataGridView1.RowCount - 1) return;
DynamicNumberFieldsClass objectInRow = (DynamicNumberFieldsClass)this._people[e.RowIndex];
// Set the cell value to paint using the DynamicNumberFieldsClass object retrieved.
switch (this.dataGridView1.Columns[e.ColumnIndex].Name)
{
case "FullName":
e.Value = objectInRow.FullName;
break;
default:
e.Value = objectInRow.Years[e.ColumnIndex - 1];
break;
}
}
where _people is a collection of DynamicNumberFieldsClass.
Form Load:
private void Form1_Load(object sender, EventArgs e)
{
this.dataGridView1.VirtualMode = true;
this.dataGridView1.CellValueNeeded += new DataGridViewCellValueEventHandler(dataGridView1_CellValueNeeded);
// Add columns to the DataGridView.
DataGridViewTextBoxColumn fullNameColumn = new
DataGridViewTextBoxColumn();
fullNameColumn.HeaderText = "FullName";
fullNameColumn.Name = "FullName";
this.dataGridView1.Columns.Add(fullNameColumn);
for (int i = 0; i < _numYears; i++)
{
DataGridViewTextBoxColumn yearIColumn = new
DataGridViewTextBoxColumn();
yearIColumn.HeaderText = "Year" + (i+1);
yearIColumn.Name = "Year" + (i+1);
this.dataGridView1.Columns.Add(yearIColumn);
}
this.dataGridView1.AutoSizeColumnsMode =
DataGridViewAutoSizeColumnsMode.AllCells;
// Set the row count, including the row for new records.
this.dataGridView1.RowCount = 3; //two objects in _people and the empty row
}
where _numYears is the fixed value you mentioned. If you have at least one instance of the object available, you could use the size of the Years array in that instance as the loop limiter, so that it is completely dynamic.
You would need to expand the switch statement if any other properties are included in the class, and of course add more error checking in general. The walkthrough shows how to support editing in the DataGridView, as well.
(I know you asked how to bind the columns, not force their values, so you probably wanted to be able to decorate the class definition, assign the data source, and go. To that end, I first looked into doing this with Reflection via CustomTypeDescriptor and TypeDescriptionProvider, etc., which is how second-level properties can be bound. Of course, the individual elements of the array are not exposed as properties, so this doesn't work. I can't think of a way to support auto-generation of the columns the way you want, but maybe someone else will find one.)