Datagridview comboboxcolumn different values for each row
I want to create a datagridview with comboboxcolumns using C #.
The problem is I don't know how to give different values for the combobox on each line.
DataTable dt = new DataTable();
dt.Columns.Add("state");
dt.Columns.Add("city");
dt.Rows.Add("a1", "b1");
dt.Rows.Add("a1", "b2");
dt.Rows.Add("a2", "b3");
dt.Rows.Add("a2", "b4");
dt.Rows.Add("a3", "b5");
DataGridViewComboBoxColumn comboStates = new DataGridViewComboBoxColumn();
comboStates.HeaderText = "HeaderText_1";
this.dataGridView1.Columns.Insert(0, comboStates);
DataGridViewComboBoxColumn comboCities = new DataGridViewComboBoxColumn();
comboCities.HeaderText = "HeaderText_2";
this.dataGridView1.Columns.Insert(1, comboCities);
for (int i = 0; i < dt.Rows.Count; i++)
{
dataGridView1.Rows.Add();
comboStates.Items.Add(dt.Rows[i][0]);
DataGridViewComboBoxCell stateCell = (DataGridViewComboBoxCell) (dataGridView1.Rows[i].Cells[0]);
stateCell.Value = comboStates.Items[i];
comboCities.Items.Add(dt.Rows[i][1]);
DataGridViewComboBoxCell cityCell = (DataGridViewComboBoxCell)(dataGridView1.Rows[i].Cells[1]);
cityCell.Value = comboCities.Items[i];
}
This example shows the following results:
for each line:
comboboxcolumnstate:
a1
a1
a2
a2
a3
comboboxcolumncity:
b1
b2
b3
b4
b5
I know this is ok because I am looping through the data through the datatable.
So how can I get this result:
row1: comboboxcolumnstate comboboxcolumncity
a1 b1 - b2
row2: comboboxcolumnstate comboboxcolumncity
a2 b3 - b4
row2: comboboxcolumnstate comboboxcolumncity
a3 b5
I am new to C #. I have searched a lot, but I have not found a solution that solves this problem. thank
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Here's some sample code that should get you started.
First, I create a list of values (cities) for each state. For this, the collection is Dictionary
convenient:
Dictionary<string, List<string>> dict = new Dictionary<string, List<string>>();
for (int i = 0; i < dt.Rows.Count; i++)
{
string state = dt.Rows[i][0].ToString();
string city = dt.Rows[i][1].ToString();
if (! dict.Keys.Contains(state )) dict.Add(state, new List<string>());
dict[state].Add(city);
}
I loop over your table, and for each row, I add a new entry for city and, if necessary, for state.
We will now change the DGV setting to use the ones Lists
in Items
each DataGridViewComboBoxCell
.
Note: here the key must use DataGridViewComboBoxCells
and not DataGridViewComboBoxColumns
!
For ease of access, I again create string variables for the state and city values.
for (int i = 0; i < dt.Rows.Count; i++)
{
string state = dt.Rows[i][0].ToString();
string city = dt.Rows[i][1].ToString();
dataGridView1.Rows.Add();
DataGridViewComboBoxCell stateCell =
(DataGridViewComboBoxCell)(dataGridView1.Rows[i].Cells[0]);
stateCell.Items.AddRange(dict.Keys.ToArray());
stateCell.Value = state;
DataGridViewComboBoxCell cityCell =
(DataGridViewComboBoxCell)(dataGridView1.Rows[i].Cells[1]);
cityCell.Items.AddRange(dict[state].ToArray());
cityCell.Value = city;
}
Note. This sets the values to DropDowns, but after every change in the "State" column, you will need to adapt the "Cities" column in that row! So it would be a good idea to make it Dictionary
permanent by moving it to the class level and create a small function that you can call after such a change.
Here's an example of this function:
private void dataGridView1_CellValueChanged(object sender, DataGridViewCellEventArgs e)
{
if (e.ColumnIndex == 0)
setCities(e.RowIndex, dataGridView1.Rows[e.RowIndex].Cells[0].Value.ToString());
}
void setCities(int row, string state)
{
DataGridViewComboBoxCell cityCell =
(DataGridViewComboBoxCell)(dataGridView1.Rows[row].Cells[1]);
cityCell.Items.Clear();
cityCell.Items.AddRange(dict[state].ToArray());
cityCell.Value = cityCell.Items[0];
}
Please note that the new one cityCell.Value
appears only after exiting the edited cell!
Final note. If you really only want to display one row for each state, you need to change the loop that fills DGV
in so that the loop is not over your table, but through the collection dict.Keys
:
for (int i = 0; i < dict.Keys.Count; i++)
{
string state = dict.Keys.ElementAt(i);
string city1 = dict[state][0].ToString();
dataGridView1.Rows.Add();
DataGridViewComboBoxCell stateCell =
(DataGridViewComboBoxCell)(dataGridView1.Rows[i].Cells[0]);
stateCell.Items.AddRange(dict.Keys.ToArray());
stateCell.Value = state;
DataGridViewComboBoxCell cityCell =
(DataGridViewComboBoxCell)(dataGridView1.Rows[i].Cells[1]);
cityCell.Items.AddRange(dict[state].ToArray());
cityCell.Value = city1;
}
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