ComboBox 以编程方式添加到 DataGridView 单元格中，单元格单击时未展开
ComboBox added programmatically to DataGridView cell not expanding on cell click
我在 C# WinForms 项目中有一个 DataGridView，当用户单击某些 DGV 单元格时，该单元格变为 DataGridViewComboBoxCell 并且 ComboBox 填充了一些值供用户 select。这是 DataGridView_Click 事件的表单代码：
private void dgvCategories_Click(Object sender, DataGridViewCellEventArgs e)
{
if (e.ColumnIndex == 5 && !(dgvCategories.Rows[e.RowIndex].Cells[e.ColumnIndex].GetType().Name == "DataGridViewComboBoxCell"))
{
// Bind combobox to dgv and than bind new values datasource to combobox
DataGridViewComboBoxCell cboNewValueList = new DataGridViewComboBoxCell();
// Get fields to build New Value query
List<string> lsNewValuesResult = new List<string>();
string strCategory = dtCategories.Rows[e.RowIndex][1].ToString();
string strCompanyName = cboSelectCompany.Text;
string strQueryGetNewValuesValidationInfo = "SELECT validationdb, validationtable, validationfield, validationfield2, validationvalue2" +
" FROM masterfiles.categories" +
" WHERE category = @category";
//" WHERE category = '" + strCategory + "'";
// Pass validation info query to db and return list of New Values
db getListOfNewValues = new db();
lsNewValuesResult = getListOfNewValues.GetNewValuesList(strQueryGetNewValuesValidationInfo, strCategory, strCompanyName);
//Populate the combobox with the list of New Values
foreach (string strListItem in lsNewValuesResult)
{
cboNewValueList.Items.Add(strListItem);
}
//
dgvCategories[e.ColumnIndex, e.RowIndex] = cboNewValueList;
}
}
这是数据库 class 中填充 ComboBox 的代码（出于这个问题的目的，这可能没有必要包括在内，但为了完整起见，我将其包括在案例是否相关）：
public List<string> GetNewValuesList(string strValidationInfoQuery, string strCategory, string strCompanyName)
{
List<string> lsValidationInfo = new List<string>();
List<string> lsNewValuesList = new List<string>();
using (NpgsqlConnection conn = new NpgsqlConnection(connString))
using (NpgsqlCommand cmd = new NpgsqlCommand(strValidationInfoQuery, conn))
{
cmd.Parameters.AddWithValue("category", strCategory);
conn.Open();
using (NpgsqlDataReader reader = cmd.ExecuteReader())
{
while (reader.Read())
{
int intReaderIndex;
for (intReaderIndex = 0; intReaderIndex <= reader.FieldCount - 1; intReaderIndex++)
{
// reader indexes 3 & 4 correspond to categories.validationfield2 and validationvalue2, which can be null
if (string.IsNullOrEmpty(reader[intReaderIndex].ToString()))
{
lsValidationInfo.Add("");
}
else
{
lsValidationInfo.Add(reader.GetString(intReaderIndex));
}
//Console.WriteLine("reader index " + intReaderIndex + ": " + reader.GetString(intReaderIndex));
}
}
}
}
string strValidationDb = lsValidationInfo[0];
string strValidationTable = lsValidationInfo[1];
string strValidationField = lsValidationInfo[2];
string strValidationField2 = lsValidationInfo[3];
string strValidationValue2 = lsValidationInfo[4];
string strQueryGetNewValues = "SELECT DISTINCT " + strValidationField +
" FROM " + strValidationDb + "." + strValidationTable +
" WHERE company_id = (SELECT id FROM company WHERE name = '" + strCompanyName + "')";
if (!string.IsNullOrEmpty(strValidationField2) && !string.IsNullOrEmpty(strValidationValue2)) strQueryGetNewValues += " AND " + strValidationField2 + " = '" + strValidationValue2 + "'";
strQueryGetNewValues += " ORDER BY " + strValidationField;
using (NpgsqlConnection conn = new NpgsqlConnection(connString))
using (NpgsqlCommand cmd = new NpgsqlCommand(strQueryGetNewValues, conn))
{
conn.Open();
using (NpgsqlDataReader reader = cmd.ExecuteReader())
{
while (reader.Read())
{
int intReaderIndex;
for (intReaderIndex = 0; intReaderIndex <= reader.FieldCount - 1; intReaderIndex++)
{
// reader indexes 3 & 4 correspond to categories.validationfield2 and validationvalue2, which can be null
if (string.IsNullOrEmpty(reader[intReaderIndex].ToString()))
{
lsNewValuesList.Add("");
}
else
{
lsNewValuesList.Add(reader.GetString(intReaderIndex));
}
Console.WriteLine("reader index " + intReaderIndex + ": " + reader.GetString(intReaderIndex));
}
}
}
}
return lsNewValuesList;
}
组合框正在填充，因为我可以在 _Click 方法中访问 lsNewValuesResult 中的项目。 DGV 编辑模式设置为 EditOnEnter。我试过 EditOnKeystroke，但这并没有导致组合框在鼠标单击时展开。
这是单击单元格时组合框的样子，CBO 已填充并添加到 DGV 单元格：
那是在我分别单击两个单元格之后。
[已解决]
请参阅下面我的回答。
不幸地解决了这个 revealed a new issue。
您可能需要关闭 AutoGenerateColumns：
此外，似乎需要单击三下才能弹出下拉菜单。
public Form1()
{
InitializeComponent();
dataGridView1.AutoGenerateColumns = false;
dataGridView1.DataSource = GetDataSource();
DataGridViewComboBoxColumn dgvcbc = new DataGridViewComboBoxColumn();
dgvcbc.Items.Add("R0C0");
dgvcbc.Items.Add("R1C0");
dgvcbc.Items.Add("R2C0");
dgvcbc.Items.Add("R3C0");
dgvcbc.DataPropertyName = "Col0";
dataGridView1.Columns.Add(dgvcbc);
}
DataTable GetDataSource()
{
var dtb = new DataTable();
dtb.Columns.Add("Col0", typeof(string));
dtb.Columns.Add("Col1", typeof(string));
dtb.Columns.Add("Col2", typeof(string));
dtb.Columns.Add("Col3", typeof(string));
dtb.Columns.Add("Col4", typeof(string));
dtb.Rows.Add("R0C0", "R0C1", "R0C2", "R0C3", "R0C4");
dtb.Rows.Add("R1C0", "R1C1", "R1C2", "R1C3", "R1C4");
dtb.Rows.Add("R2C0", "R2C1", "R2C2", "R2C3", "R2C4");
dtb.Rows.Add("R3C0", "R3C1", "R3C2", "R3C3", "R3C4");
return dtb;
}
您可以考虑以下有关 DataGridView 的事实：
如果将 AutoGenerateColumns 设置为 false，则需要手动将列添加到 Columns 集合。
如果将 AutoGenerateColumns 设置为 true，当您将数据分配给 DataSource 时，控件会自动为数据源生成列。在这种情况下，控件会在数据源的列列表中查找每一列，如果控件的 Columns 集合中没有与数据源的列名具有相同 DataPropertyName 的列，它将向 Columns 集合添加一列。
DataPropertyName datagridviews 的列决定了数据源的绑定列。
您通常希望将 DataGridViewXXXXColumn 添加到列集合而不是对单元格使用 DataGridViewXXXXCell。
如果你设置EditMode为EditOnEnter，那么如果你点击下拉按钮，点击一次就够了。如果单击单元格内容，则需要单击两次。
如果您希望即使单击单元格内容也可以单击它，请查看。 （注：我没用过这个是例子，有点烦人。）
您可以设置DisplayStyle to Nothing，然后它会将列显示为组合框，只是在编辑模式下。
使用 DataGridViewComboBoxColumn 的基本示例
我想您要在 DataGridView 中显示具有 (Id, Name, Price, CategoryId) 的产品列表，并且 CategoryId 应该来自具有 (Id, Name) 和您要将 CategoryId 显示为 ComboBox。
实际上这是DataGridViewComboBoxColumn的一个基本和经典的例子：
private void Form1_Load(object sender, EventArgs e) {
var categories = GetCategories();
var products = GetProducts();
var idColumn = new DataGridViewTextBoxColumn() {
Name = "Id", HeaderText = "Id", DataPropertyName = "Id"
};
var nameColumn = new DataGridViewTextBoxColumn() {
Name = "Name", HeaderText = "Name", DataPropertyName = "Name"
};
var priceColumn = new DataGridViewTextBoxColumn() {
Name = "Price", HeaderText = "Price", DataPropertyName = "Price"
};
var categoryIdColumn = new DataGridViewComboBoxColumn() {
Name = "CategoryId", HeaderText = "Category Id", DataPropertyName = "CategoryId",
DataSource = categories, DisplayMember = "Name", ValueMember = "Id",
DisplayStyle = DataGridViewComboBoxDisplayStyle.Nothing
};
dataGridView1.Columns.AddRange(idColumn, nameColumn, priceColumn, categoryIdColumn);
dataGridView1.EditMode = DataGridViewEditMode.EditOnEnter;
dataGridView1.AutoGenerateColumns = false;
dataGridView1.DataSource = products;
}
public DataTable GetProducts() {
var products = new DataTable();
products.Columns.Add("Id", typeof(int));
products.Columns.Add("Name", typeof(string));
products.Columns.Add("Price", typeof(int));
products.Columns.Add("CategoryId", typeof(int));
products.Rows.Add(1, "Product 1", 100, 1);
products.Rows.Add(2, "Product 2", 200, 2);
return products;
}
public DataTable GetCategories() {
var categories = new DataTable();
categories.Columns.Add("Id", typeof(int));
categories.Columns.Add("Name", typeof(string));
categories.Rows.Add(1, "Category 1");
categories.Rows.Add(2, "Category 2");
return categories;
}
了解更多
要了解有关 DataGridView 的更多信息，请查看 DataGridView Control (Windows Forms)。它包含一些文档和有用的 How To 文章的链接，包括：
您是否遇到了由于某种原因未显示的错误？
如果我使用你的代码，DataGridViewComboBoxCell 似乎填充了值，但我得到 DataGridViewComboBoxCell value is not valid 运行时错误。
这个测试代码对我来说工作正常：
private void dgvCategories_CellContentClick(object sender, DataGridViewCellEventArgs e)
{
DataGridViewComboBoxCell cboNewValueList = new DataGridViewComboBoxCell();
List<string> lsNewValuesResult = new List<string>();
lsNewValuesResult.Add("Value1");
lsNewValuesResult.Add("Value2");
lsNewValuesResult.Add("Value3");
foreach (string strListItem in lsNewValuesResult)
{
cboNewValueList.Items.Add(strListItem);
}
dgvCategories[e.ColumnIndex, e.RowIndex] = cboNewValueList;
// Added setting of initial value
cboNewValueList.Value = cboNewValueList.Items[0];
}
因此，也许在将 DataGridViewComboBoxCell 添加到 DataGridView 之后尝试设置其初始值。
如果我正确识别你的问题，我会在我的测试应用程序中添加一个 DataGridView whit 6 列，EditMode = EditOnEnter
（其他的需要点击三次打开下拉菜单，据我所知）并处理CellStateChanged事件。
private void dgvCategories_CellStateChanged(object sender, DataGridViewCellStateChangedEventArgs e)
{
if (e.StateChanged == DataGridViewElementStates.Selected)
{
DataGridViewCell cell = e.Cell;
int columnIndex = cell.ColumnIndex;
int rowIndex = cell.RowIndex;
//---IF CONDITIONS--
//columnIndex == 5
// Only cells in Columns[5]
//cell.Selected
// Because this event raised two time, first for last selected cell and once again
// for currently selected cell and we need only currently selected cell.
//cell.EditType.Name != "DataGridViewComboBoxEditingControl"
// If this cell "CellStateChanged" raised for second time, only other cell types allowed
// to edit, otherwise the current cell lost last selected item.
if (columnIndex == 5 && cell.Selected && cell.EditType.Name != "DataGridViewComboBoxEditingControl")
{
DataGridViewComboBoxCell cboNewValueList = new DataGridViewComboBoxCell();
//Add items to DataGridViewComboBoxCell for test, replace it with yours.
for (int i = 0; i < 10; i++)
cboNewValueList.Items.Add($"Item {i}");
dgvCategories[columnIndex, rowIndex] = cboNewValueList;
}
}
}
NOTE: user must click two time in a cell to open drop down menu.
编辑一个： 正如 Reza Aghaei 建议在单元格中单击：
private void dgvCategories_CellClick(object sender, DataGridViewCellEventArgs e)
{
DataGridViewComboBoxEditingControl editingControl = dgvCategories.EditingControl as DataGridViewComboBoxEditingControl;
if (editingControl != null)
editingControl.DroppedDown = true;
}
我要公开承认我傻了:
出于该项目所需的设计和功能原因，我手动设置 DGV 列的宽度和名称，并且我还需要第 2 到第 4 列 ReadOnly = true。好吧，我无意中设置了第5列-这个问题即将ReadOnly = true的列。
感谢大家的回答。这只是提醒我们，如此简单的事情可能会导致一个看似大的问题，而且很容易被忽视！
我在 C# WinForms 项目中有一个 DataGridView，当用户单击某些 DGV 单元格时，该单元格变为 DataGridViewComboBoxCell 并且 ComboBox 填充了一些值供用户 select。这是 DataGridView_Click 事件的表单代码：
private void dgvCategories_Click(Object sender, DataGridViewCellEventArgs e)
{
if (e.ColumnIndex == 5 && !(dgvCategories.Rows[e.RowIndex].Cells[e.ColumnIndex].GetType().Name == "DataGridViewComboBoxCell"))
{
// Bind combobox to dgv and than bind new values datasource to combobox
DataGridViewComboBoxCell cboNewValueList = new DataGridViewComboBoxCell();
// Get fields to build New Value query
List<string> lsNewValuesResult = new List<string>();
string strCategory = dtCategories.Rows[e.RowIndex][1].ToString();
string strCompanyName = cboSelectCompany.Text;
string strQueryGetNewValuesValidationInfo = "SELECT validationdb, validationtable, validationfield, validationfield2, validationvalue2" +
" FROM masterfiles.categories" +
" WHERE category = @category";
//" WHERE category = '" + strCategory + "'";
// Pass validation info query to db and return list of New Values
db getListOfNewValues = new db();
lsNewValuesResult = getListOfNewValues.GetNewValuesList(strQueryGetNewValuesValidationInfo, strCategory, strCompanyName);
//Populate the combobox with the list of New Values
foreach (string strListItem in lsNewValuesResult)
{
cboNewValueList.Items.Add(strListItem);
}
//
dgvCategories[e.ColumnIndex, e.RowIndex] = cboNewValueList;
}
}
这是数据库 class 中填充 ComboBox 的代码（出于这个问题的目的，这可能没有必要包括在内，但为了完整起见，我将其包括在案例是否相关）：
public List<string> GetNewValuesList(string strValidationInfoQuery, string strCategory, string strCompanyName)
{
List<string> lsValidationInfo = new List<string>();
List<string> lsNewValuesList = new List<string>();
using (NpgsqlConnection conn = new NpgsqlConnection(connString))
using (NpgsqlCommand cmd = new NpgsqlCommand(strValidationInfoQuery, conn))
{
cmd.Parameters.AddWithValue("category", strCategory);
conn.Open();
using (NpgsqlDataReader reader = cmd.ExecuteReader())
{
while (reader.Read())
{
int intReaderIndex;
for (intReaderIndex = 0; intReaderIndex <= reader.FieldCount - 1; intReaderIndex++)
{
// reader indexes 3 & 4 correspond to categories.validationfield2 and validationvalue2, which can be null
if (string.IsNullOrEmpty(reader[intReaderIndex].ToString()))
{
lsValidationInfo.Add("");
}
else
{
lsValidationInfo.Add(reader.GetString(intReaderIndex));
}
//Console.WriteLine("reader index " + intReaderIndex + ": " + reader.GetString(intReaderIndex));
}
}
}
}
string strValidationDb = lsValidationInfo[0];
string strValidationTable = lsValidationInfo[1];
string strValidationField = lsValidationInfo[2];
string strValidationField2 = lsValidationInfo[3];
string strValidationValue2 = lsValidationInfo[4];
string strQueryGetNewValues = "SELECT DISTINCT " + strValidationField +
" FROM " + strValidationDb + "." + strValidationTable +
" WHERE company_id = (SELECT id FROM company WHERE name = '" + strCompanyName + "')";
if (!string.IsNullOrEmpty(strValidationField2) && !string.IsNullOrEmpty(strValidationValue2)) strQueryGetNewValues += " AND " + strValidationField2 + " = '" + strValidationValue2 + "'";
strQueryGetNewValues += " ORDER BY " + strValidationField;
using (NpgsqlConnection conn = new NpgsqlConnection(connString))
using (NpgsqlCommand cmd = new NpgsqlCommand(strQueryGetNewValues, conn))
{
conn.Open();
using (NpgsqlDataReader reader = cmd.ExecuteReader())
{
while (reader.Read())
{
int intReaderIndex;
for (intReaderIndex = 0; intReaderIndex <= reader.FieldCount - 1; intReaderIndex++)
{
// reader indexes 3 & 4 correspond to categories.validationfield2 and validationvalue2, which can be null
if (string.IsNullOrEmpty(reader[intReaderIndex].ToString()))
{
lsNewValuesList.Add("");
}
else
{
lsNewValuesList.Add(reader.GetString(intReaderIndex));
}
Console.WriteLine("reader index " + intReaderIndex + ": " + reader.GetString(intReaderIndex));
}
}
}
}
return lsNewValuesList;
}
组合框正在填充，因为我可以在 _Click 方法中访问 lsNewValuesResult 中的项目。 DGV 编辑模式设置为 EditOnEnter。我试过 EditOnKeystroke，但这并没有导致组合框在鼠标单击时展开。
这是单击单元格时组合框的样子，CBO 已填充并添加到 DGV 单元格：
那是在我分别单击两个单元格之后。
[已解决]
请参阅下面我的回答。
不幸地解决了这个 revealed a new issue。
您可能需要关闭 AutoGenerateColumns：
此外，似乎需要单击三下才能弹出下拉菜单。
public Form1()
{
InitializeComponent();
dataGridView1.AutoGenerateColumns = false;
dataGridView1.DataSource = GetDataSource();
DataGridViewComboBoxColumn dgvcbc = new DataGridViewComboBoxColumn();
dgvcbc.Items.Add("R0C0");
dgvcbc.Items.Add("R1C0");
dgvcbc.Items.Add("R2C0");
dgvcbc.Items.Add("R3C0");
dgvcbc.DataPropertyName = "Col0";
dataGridView1.Columns.Add(dgvcbc);
}
DataTable GetDataSource()
{
var dtb = new DataTable();
dtb.Columns.Add("Col0", typeof(string));
dtb.Columns.Add("Col1", typeof(string));
dtb.Columns.Add("Col2", typeof(string));
dtb.Columns.Add("Col3", typeof(string));
dtb.Columns.Add("Col4", typeof(string));
dtb.Rows.Add("R0C0", "R0C1", "R0C2", "R0C3", "R0C4");
dtb.Rows.Add("R1C0", "R1C1", "R1C2", "R1C3", "R1C4");
dtb.Rows.Add("R2C0", "R2C1", "R2C2", "R2C3", "R2C4");
dtb.Rows.Add("R3C0", "R3C1", "R3C2", "R3C3", "R3C4");
return dtb;
}
您可以考虑以下有关 DataGridView 的事实：
如果将
AutoGenerateColumns设置为false，则需要手动将列添加到Columns集合。如果将
AutoGenerateColumns设置为true，当您将数据分配给DataSource时，控件会自动为数据源生成列。在这种情况下，控件会在数据源的列列表中查找每一列，如果控件的Columns集合中没有与数据源的列名具有相同DataPropertyName的列，它将向Columns集合添加一列。DataPropertyNamedatagridviews 的列决定了数据源的绑定列。您通常希望将
DataGridViewXXXXColumn添加到列集合而不是对单元格使用DataGridViewXXXXCell。如果你设置
EditMode为EditOnEnter，那么如果你点击下拉按钮，点击一次就够了。如果单击单元格内容，则需要单击两次。如果您希望即使单击单元格内容也可以单击它，请查看
您可以设置
DisplayStyletoNothing，然后它会将列显示为组合框，只是在编辑模式下。
使用 DataGridViewComboBoxColumn 的基本示例
我想您要在 DataGridView 中显示具有 (Id, Name, Price, CategoryId) 的产品列表，并且 CategoryId 应该来自具有 (Id, Name) 和您要将 CategoryId 显示为 ComboBox。
实际上这是DataGridViewComboBoxColumn的一个基本和经典的例子：
private void Form1_Load(object sender, EventArgs e) {
var categories = GetCategories();
var products = GetProducts();
var idColumn = new DataGridViewTextBoxColumn() {
Name = "Id", HeaderText = "Id", DataPropertyName = "Id"
};
var nameColumn = new DataGridViewTextBoxColumn() {
Name = "Name", HeaderText = "Name", DataPropertyName = "Name"
};
var priceColumn = new DataGridViewTextBoxColumn() {
Name = "Price", HeaderText = "Price", DataPropertyName = "Price"
};
var categoryIdColumn = new DataGridViewComboBoxColumn() {
Name = "CategoryId", HeaderText = "Category Id", DataPropertyName = "CategoryId",
DataSource = categories, DisplayMember = "Name", ValueMember = "Id",
DisplayStyle = DataGridViewComboBoxDisplayStyle.Nothing
};
dataGridView1.Columns.AddRange(idColumn, nameColumn, priceColumn, categoryIdColumn);
dataGridView1.EditMode = DataGridViewEditMode.EditOnEnter;
dataGridView1.AutoGenerateColumns = false;
dataGridView1.DataSource = products;
}
public DataTable GetProducts() {
var products = new DataTable();
products.Columns.Add("Id", typeof(int));
products.Columns.Add("Name", typeof(string));
products.Columns.Add("Price", typeof(int));
products.Columns.Add("CategoryId", typeof(int));
products.Rows.Add(1, "Product 1", 100, 1);
products.Rows.Add(2, "Product 2", 200, 2);
return products;
}
public DataTable GetCategories() {
var categories = new DataTable();
categories.Columns.Add("Id", typeof(int));
categories.Columns.Add("Name", typeof(string));
categories.Rows.Add(1, "Category 1");
categories.Rows.Add(2, "Category 2");
return categories;
}
了解更多
要了解有关 DataGridView 的更多信息，请查看 DataGridView Control (Windows Forms)。它包含一些文档和有用的 How To 文章的链接，包括：
您是否遇到了由于某种原因未显示的错误？
如果我使用你的代码，DataGridViewComboBoxCell 似乎填充了值，但我得到 DataGridViewComboBoxCell value is not valid 运行时错误。
这个测试代码对我来说工作正常：
private void dgvCategories_CellContentClick(object sender, DataGridViewCellEventArgs e)
{
DataGridViewComboBoxCell cboNewValueList = new DataGridViewComboBoxCell();
List<string> lsNewValuesResult = new List<string>();
lsNewValuesResult.Add("Value1");
lsNewValuesResult.Add("Value2");
lsNewValuesResult.Add("Value3");
foreach (string strListItem in lsNewValuesResult)
{
cboNewValueList.Items.Add(strListItem);
}
dgvCategories[e.ColumnIndex, e.RowIndex] = cboNewValueList;
// Added setting of initial value
cboNewValueList.Value = cboNewValueList.Items[0];
}
因此，也许在将 DataGridViewComboBoxCell 添加到 DataGridView 之后尝试设置其初始值。
如果我正确识别你的问题，我会在我的测试应用程序中添加一个 DataGridView whit 6 列，EditMode = EditOnEnter
（其他的需要点击三次打开下拉菜单，据我所知）并处理CellStateChanged事件。
private void dgvCategories_CellStateChanged(object sender, DataGridViewCellStateChangedEventArgs e)
{
if (e.StateChanged == DataGridViewElementStates.Selected)
{
DataGridViewCell cell = e.Cell;
int columnIndex = cell.ColumnIndex;
int rowIndex = cell.RowIndex;
//---IF CONDITIONS--
//columnIndex == 5
// Only cells in Columns[5]
//cell.Selected
// Because this event raised two time, first for last selected cell and once again
// for currently selected cell and we need only currently selected cell.
//cell.EditType.Name != "DataGridViewComboBoxEditingControl"
// If this cell "CellStateChanged" raised for second time, only other cell types allowed
// to edit, otherwise the current cell lost last selected item.
if (columnIndex == 5 && cell.Selected && cell.EditType.Name != "DataGridViewComboBoxEditingControl")
{
DataGridViewComboBoxCell cboNewValueList = new DataGridViewComboBoxCell();
//Add items to DataGridViewComboBoxCell for test, replace it with yours.
for (int i = 0; i < 10; i++)
cboNewValueList.Items.Add($"Item {i}");
dgvCategories[columnIndex, rowIndex] = cboNewValueList;
}
}
}
NOTE: user must click two time in a cell to open drop down menu.
编辑一个： 正如 Reza Aghaei 建议在单元格中单击：
private void dgvCategories_CellClick(object sender, DataGridViewCellEventArgs e)
{
DataGridViewComboBoxEditingControl editingControl = dgvCategories.EditingControl as DataGridViewComboBoxEditingControl;
if (editingControl != null)
editingControl.DroppedDown = true;
}
我要公开承认我傻了:
出于该项目所需的设计和功能原因，我手动设置 DGV 列的宽度和名称，并且我还需要第 2 到第 4 列 ReadOnly = true。好吧，我无意中设置了第5列-这个问题即将ReadOnly = true的列。
感谢大家的回答。这只是提醒我们，如此简单的事情可能会导致一个看似大的问题，而且很容易被忽视！