State，County和City级联组合框。 我刚刚创建了一个带有datagridview的简单表单。 datagridview包含3个组合框（州，县和市）。当您选择州时，县组合框应仅显示该州内的县，当您选择县时，城市列应仅显示所选州和县内的城市。我需要能够在任何时候改变州和县，这应该重置其他相应的列。
using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Windows.Forms;
namespace StateCountyCityDataGridViewComboboxColumnIssue
{
public partial class Form1 : Form
{
private DataTable dtStateCountyCity = new DataTable();
public Form1()
{
InitializeComponent();
dtStateCountyCity = CreateDataTable_StateCountyCity();
var stateList = (from scc in dtStateCountyCity.AsEnumerable()
group scc by scc.Field<string>("state") into g
select new { State = g.Key }).ToList();
dgvCmbColState.DataSource = stateList;
dgvCmbColState.DisplayMember = "state";
dgvCmbColState.ValueMember = "state";
}
public DataTable CreateDataTable_StateCountyCity()
{
DataTable dt = new DataTable();
dt.Columns.Add("State", typeof(string));
dt.Columns.Add("County", typeof(string));
dt.Columns.Add("City", typeof(string));
dt.Rows.Add("Michigan", "Oakland", "Royal Oak");
dt.Rows.Add("Michigan", "Oakland", "Birmingham");
dt.Rows.Add("Michigan", "Oakland", "Troy");
dt.Rows.Add("Michigan", "Macomb", "Sterling Heights");
dt.Rows.Add("Michigan", "Macomb", "Warren");
dt.Rows.Add("Illinois", "Cook", "Chicago");
dt.Rows.Add("Illinois", "Cook", "Alsip");
dt.Rows.Add("Illinois", "Cook", "Oak Park");
dt.Rows.Add("Illinois", "Clinton", "Albers");
dt.Rows.Add("Illinois", "Clinton", "Aviston");
return dt;
}
private void CountyComboBox_DropDown(object sender, EventArgs e)
{
//Int64 xRefID = Convert.ToInt64(dgvDepartmentWorkersComp.CurrentRow.Cells[6].Value);
if (dgvStateCountyCity.CurrentRow.Cells[0].Value != null)
{
string stateSelected = dgvStateCountyCity.CurrentRow.Cells[0].Value.ToString();
DataRow[] drTempRows = dtStateCountyCity.Select("State = '" + stateSelected + "'");
if (drTempRows != null && drTempRows.Length > 0)
{
DataTable dtTemp = drTempRows.CopyToDataTable();
var countyList = (from tblCounty in dtTemp.AsEnumerable()
group tblCounty by tblCounty.Field<string>("county") into g
select new { County = g.Key }).ToList();
BindingSource bs = new BindingSource(countyList, "");
dgvCmbColCounty.DataSource = bs;
dgvCmbColCounty.DisplayMember = "County";
dgvCmbColCounty.ValueMember = "County";
}
}
}
private void CityComboBox_DropDown(object sender, EventArgs e)
{
//Int64 xRefID = Convert.ToInt64(dgvDepartmentWorkersComp.CurrentRow.Cells[6].Value);
if (dgvStateCountyCity.CurrentRow.Cells[1].Value != null)
{
string countySelected = dgvStateCountyCity.CurrentRow.Cells[1].Value.ToString();
DataRow[] drTempRows = dtStateCountyCity.Select("County = '" + countySelected + "'");
if (drTempRows != null && drTempRows.Length > 0)
{
DataTable dtTemp = drTempRows.CopyToDataTable();
BindingSource bs = new BindingSource(dtTemp, "");
dgvCmbColCity.DataSource = bs;
dgvCmbColCity.DisplayMember = "City";
dgvCmbColCity.ValueMember = "City";
}
}
}
private void StateSelectionChanged(object sender, EventArgs e)
{
}
private void dgvStateCountyCity_EditingControlShowing(object sender, DataGridViewEditingControlShowingEventArgs e)
{
int stateColumnIndex = 0;
int countyColumnIndex = 1;
int cityColumnIndex = 2;
if (e.Control is ComboBox)
{
if (dgvStateCountyCity.CurrentCell.ColumnIndex == countyColumnIndex)
{
ComboBox CountyComboBox = e.Control as ComboBox;
if (CountyComboBox != null)
{
CountyComboBox.DropDown += new EventHandler(CountyComboBox_DropDown);
}
}
if (dgvStateCountyCity.CurrentCell.ColumnIndex == cityColumnIndex)
{
ComboBox CityComboBox = e.Control as ComboBox;
if (CityComboBox != null)
{
CityComboBox.DropDown += new EventHandler(CityComboBox_DropDown);
}
}
//register selectedvaluechanged event and reset item combobox to default if category changes
if (dgvStateCountyCity.CurrentCell != null && dgvStateCountyCity.CurrentCell.ColumnIndex == stateColumnIndex)
{
ComboBox StateComboBox = e.Control as ComboBox;
if (StateComboBox != null)
{
StateComboBox.SelectedValueChanged += new EventHandler(StateSelectionChanged);
}
}
}
}
//Because filtering this way can make some cell have a value which is not contained in
//the DataGridViewComboBoxColumn.Items, we have to handle the DataError
private void dgvStateCountyCity_DataError(object sender, DataGridViewDataErrorEventArgs e)
{
//We're interested only in DataGridViewComboBoxColumn
if (dgvStateCountyCity.Columns[e.ColumnIndex] is DataGridViewComboBoxColumn)
{
e.Cancel = true;
}
}
}
}
关于完成此操作的任何想法？非常感谢帮助！
答案 0 :(得分：0)
我发现答案隐藏在其他地方。所以我修复了我的代码，就在这里。关键是你必须使用DataGridViewComboBoxCell。这是一个完整的样本。使用你想要的，没有警告。
using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Windows.Forms;
namespace StateCountyCityDataGridViewComboboxColumnIssue
{
public partial class Form1 : Form
{
private DataTable dtStateCountyCity = new DataTable();
public Form1()
{
InitializeComponent();
dtStateCountyCity = CreateDataTable_StateCountyCity();
var stateList = (from scc in dtStateCountyCity.AsEnumerable()
group scc by scc.Field<string>("state") into g
select new { State = g.Key }).ToList();
dgvCmbColState.DataSource = stateList;
dgvCmbColState.DisplayMember = "state";
dgvCmbColState.ValueMember = "state";
}
public DataTable CreateDataTable_StateCountyCity()
{
DataTable dt = new DataTable();
dt.Columns.Add("State", typeof(string));
dt.Columns.Add("County", typeof(string));
dt.Columns.Add("City", typeof(string));
dt.Rows.Add("Michigan", "Oakland", "Royal Oak");
dt.Rows.Add("Michigan", "Oakland", "Birmingham");
dt.Rows.Add("Michigan", "Oakland", "Troy");
dt.Rows.Add("Michigan", "Macomb", "Sterling Heights");
dt.Rows.Add("Michigan", "Macomb", "Warren");
dt.Rows.Add("Illinois", "Cook", "Chicago");
dt.Rows.Add("Illinois", "Cook", "Alsip");
dt.Rows.Add("Illinois", "Cook", "Oak Park");
dt.Rows.Add("Illinois", "Clinton", "Albers");
dt.Rows.Add("Illinois", "Clinton", "Aviston");
return dt;
}
//Because filtering this way can make some cell have a value which is not contained in
//the DataGridViewComboBoxColumn.Items, we have to handle the DataError
private void dgvStateCountyCity_DataError(object sender, DataGridViewDataErrorEventArgs e)
{
//We're interested only in DataGridViewComboBoxColumn
if (dgvStateCountyCity.Columns[e.ColumnIndex] is DataGridViewComboBoxColumn)
{
e.Cancel = true;
}
}
private void dgvStateCountyCity_CellClick(object sender, DataGridViewCellEventArgs e)
{
if (e.ColumnIndex == 1)
{
if (dgvStateCountyCity.CurrentRow.Cells[0].Value != null)
{
string stateSelected = dgvStateCountyCity.CurrentRow.Cells[0].Value.ToString();
DataRow[] drTempRows = dtStateCountyCity.Select("State = '" + stateSelected + "'");
if (drTempRows != null && drTempRows.Length > 0)
{
DataTable dtTemp = drTempRows.CopyToDataTable();
var countyList = (from tblCounty in dtTemp.AsEnumerable()
group tblCounty by tblCounty.Field<string>("county") into g
select new { County = g.Key }).ToList();
BindingSource bs = new BindingSource(countyList, "");
// NOTE: Here is what was changed from my previous code
DataGridViewComboBoxCell comboCell = dgvStateCountyCity[1, dgvStateCountyCity.CurrentRow.Index] as DataGridViewComboBoxCell;
comboCell.DataSource = new BindingSource(bs, null);
comboCell.DisplayMember = "County"; //name of column indataTable to display!!
comboCell.ValueMember = "County"; // vlaue if needed
}
}
}
if (e.ColumnIndex == 2)
{
if (dgvStateCountyCity.CurrentRow.Cells[1].Value != null)
{
string countySelected = dgvStateCountyCity.CurrentRow.Cells[1].Value.ToString();
DataRow[] drTempRows = dtStateCountyCity.Select("County = '" + countySelected + "'");
if (drTempRows != null && drTempRows.Length > 0)
{
DataTable dtTemp = drTempRows.CopyToDataTable();
BindingSource bs = new BindingSource(dtTemp, "");
// NOTE: Here is what was changed from my previous code
DataGridViewComboBoxCell comboCell2 = dgvStateCountyCity[2, dgvStateCountyCity.CurrentRow.Index] as DataGridViewComboBoxCell;
comboCell2.DataSource = new BindingSource(bs, null);
comboCell2.DisplayMember = "City"; //name of column indataTable to display!!
comboCell2.ValueMember = "City"; // vlaue if needed
}
}
}
}
private void dgvStateCountyCity_EditingControlShowing(object sender, DataGridViewEditingControlShowingEventArgs e)
{
//Register SelectedValueChanged event and reset item comboBox to default if category changes
if (dgvStateCountyCity.CurrentCell.ColumnIndex == 0 )
{
ComboBox comboBox = e.Control as ComboBox;
comboBox.SelectedIndexChanged -= new EventHandler(dgvcbState_SelectedValueChanged);
comboBox.SelectedIndexChanged += new EventHandler(dgvcbState_SelectedValueChanged);
}
}
private void dgvcbState_SelectedValueChanged(object sender, EventArgs e)
{
//If category value changed then reset item to default.
if (dgvStateCountyCity.CurrentCell.ColumnIndex == 0)
{
if (((DataGridViewComboBoxEditingControl)sender).EditingControlValueChanged == true)
{
dgvStateCountyCity.CurrentRow.Cells[1].Value = "";
dgvStateCountyCity.CurrentRow.Cells[2].Value = "";
}
}
}
}
}