DataGridViewComboBoxColumn Selected Value / Index

Question

I am attempting to populate a DataGridViewComboBoxColumn with a list of strings then select one of them based upon their value on form load.

A simple task one would think, but I just can't get it right.

I am populating a DataGridViewComboBoxColumn with strings as such without a problem:

ComboBoxColumn.Items.AddRange("Mr.", "Ms.", "Mrs.", "Dr.");

I also seem to be able to add it to the DataGridView without a problem (This is incorrect see Edit):

ExampleDataGrid.Rows.Add("", ComboBoxColumn, 1000, "");

Now I want to set "Mr." to be selected on load. Other posts suggest that I should be able to simply use:

ExampleDataGrid.Rows[i].Cells["ExampleColumnName"].Value = "Mr.";

But whenever I use it, I get an error that tells me the value is not valid. Is there something I'm missing?

I can however use this to get the set value without issue:

string Title = ExampleDataGrid.Rows[i].Cells["ExampleColumnName"].Value;

I had a look at the documentation but it doesn't seem to mention how to actually use .Value in this context. Microsoft Docs

Any thoughts on where I am going wrong would be great.

Edit:

The issue I was having was caused by me setting the ComboBoxItems in the "ExampleDataGrid.Rows.Add()". This should actually contain the value you want to set. e.g.

ExampleDataGrid.Rows.Add("", "Mr.", 1000, "");

`Mr.` in the combobox items has a `.` at the end. `Mr` doesn't exists in the items so setting it as value of the combobox cell will throw an exception. — Reza Aghaei, Dec 05 '18 at 17:23
Good spot, sadly that doesn't solve the issue. I get the same error message Exception = {"DataGridViewComboBoxCell value is not valid."} — tfcmad, Dec 06 '18 at 08:27
did you have a look in the debugger? what type is the object in `ExampleDataGrid.Rows[i].Cells["ExampleColumnName"]` — Mong Zhu, Dec 06 '18 at 08:38
The Cells["ExampleColumnName"] is a DataGridViewCellsCollection, but .Value shows at run time as being DataGridViewComboBoxColumn. — tfcmad, Dec 06 '18 at 08:49

Reza Aghaei · Accepted Answer · 2018-12-06T09:06:49.773

You can initialize the DataGridView this way:

private void Form1_Load(object sender, EventArgs e)
{
    var textBoxColumn = new DataGridViewTextBoxColumn();
    textBoxColumn.Name = "textBoxColumn";

    var comboBoxColumn = new DataGridViewComboBoxColumn();
    comboBoxColumn.Items.AddRange("A", "B", "C");
    comboBoxColumn.Name = "comboBoxColumn";

    dataGridView1.Columns.Add(textBoxColumn);
    dataGridView1.Columns.Add(comboBoxColumn);

    dataGridView1.Rows.Add("1", "A");
    dataGridView1.Rows.Add("2", "B");
}

And then update the value of the comboBoxColumn for the second row this way:

private void button1_Click(object sender, EventArgs e)
{
    //You can use either of the following ways:
    dataGridView1[1, 1].Value = "C";
    //dataGridView1["comboBoxColumn", 1].Value = "C";
    //dataGridView1.Rows[1].Cells["comboBoxColumn"].Value = "C";
    //dataGridView1.Rows[1].Cells[1].Value = "C";
}

The value which you set for the cell, should be between the values which you added to Items of the DataGridViewComboBoxColumn.

However, in general, I suggest using data-binding rather than using an unbound `DataGridView`. — Reza Aghaei, Dec 06 '18 at 09:00
Thank you for this, this is a good example. Looking at this I believe I was adding the combobox values in the wrong way. ExampleDataGrid.Rows.Add("", ComboBoxColumn, 1000, ""); Should be this for example ExampleDataGrid.Rows.Add("", "Mr." 1000, ""); — tfcmad, Dec 06 '18 at 09:53

DataGridViewComboBoxColumn Selected Value / Index

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