DataGridViewCellErrorTextNeededEventArgs DataGridViewCellErrorTextNeededEventArgs DataGridViewCellErrorTextNeededEventArgs DataGridViewCellErrorTextNeededEventArgs Class

定义

CellErrorTextNeeded 控件的 DataGridView 事件提供数据。Provides data for the CellErrorTextNeeded event of a DataGridView control.

public ref class DataGridViewCellErrorTextNeededEventArgs : System::Windows::Forms::DataGridViewCellEventArgs
public class DataGridViewCellErrorTextNeededEventArgs : System.Windows.Forms.DataGridViewCellEventArgs
type DataGridViewCellErrorTextNeededEventArgs = class
    inherit DataGridViewCellEventArgs
Public Class DataGridViewCellErrorTextNeededEventArgs
Inherits DataGridViewCellEventArgs
继承
DataGridViewCellErrorTextNeededEventArgsDataGridViewCellErrorTextNeededEventArgsDataGridViewCellErrorTextNeededEventArgsDataGridViewCellErrorTextNeededEventArgs

示例

在下面的代码示例演示如何创建单元格的错误消息而无需共享行或导致要复制到共享的所有单元格的单元格错误。In the following code example demonstrates how to create error messages for cells without unsharing rows or causing the cell error to be duplicated over all the shared cells.

ToolStripMenuItem^ wholeTable;
ToolStripMenuItem^ lookUp;
System::Windows::Forms::ContextMenuStrip^ strip;
String^ cellErrorText;

void dataGridView1_CellContextMenuStripNeeded( Object^ /*sender*/,
    DataGridViewCellContextMenuStripNeededEventArgs^ e )
{
    cellErrorText = String::Empty;
    if ( strip == nullptr )
    {
        strip = gcnew System::Windows::Forms::ContextMenuStrip;
        lookUp->Text = L"Look Up";
        wholeTable->Text = L"See Whole Table";
        strip->Items->Add( lookUp );
        strip->Items->Add( wholeTable );
    }

    e->ContextMenuStrip = strip;
}

void wholeTable_Click( Object^ /*sender*/, EventArgs^ /*e*/ )
{
    dataGridView1->DataSource = Populate( L"Select * from employees", true );
}

DataGridViewCellEventArgs^ theCellImHoveringOver;
void dataGridView1_CellMouseEnter( Object^ /*sender*/, DataGridViewCellEventArgs^ e )
{
    theCellImHoveringOver = e;
}

DataGridViewCellEventArgs^ cellErrorLocation;
void lookUp_Click( Object^ /*sender*/, EventArgs^ /*e*/ )
{
    try
    {
        dataGridView1->DataSource = Populate( String::Format( L"Select * from employees where {0} = '{1}'", dataGridView1->Columns[ theCellImHoveringOver->ColumnIndex ]->Name, dataGridView1->Rows[ theCellImHoveringOver->RowIndex ]->Cells[ theCellImHoveringOver->ColumnIndex ]->Value ), true );
    }
    catch ( ... ) 
    {
        cellErrorText = L"Can't look this cell up";
        cellErrorLocation = theCellImHoveringOver;
    }

}

void dataGridView1_CellErrorTextNeeded( Object^ /*sender*/, DataGridViewCellErrorTextNeededEventArgs^ e )
{
    if ( cellErrorLocation != nullptr )
    {
        if ( e->ColumnIndex == cellErrorLocation->ColumnIndex && e->RowIndex == cellErrorLocation->RowIndex )
        {
            e->ErrorText = cellErrorText;
        }
    }
}

DataTable^ Populate( String^ query, bool resetUnsharedCounter )
{
    if ( resetUnsharedCounter )
    {
        ResetCounter();
    }


    // Alter the data source as necessary
    SqlDataAdapter^ adapter = gcnew SqlDataAdapter( query,
        gcnew SqlConnection( L"Integrated Security=SSPI;Persist Security Info=False;"
        L"Initial Catalog=Northwind;Data Source= localhost" ) );
    DataTable^ table = gcnew DataTable;
    adapter->Fill( table );
    return table;
}

Label^ count;
int unsharedRowCounter;
void ResetCounter()
{
    unsharedRowCounter = 0;
    count->Text = unsharedRowCounter.ToString();
}
private ToolStripMenuItem wholeTable = new ToolStripMenuItem();
private ToolStripMenuItem lookUp = new ToolStripMenuItem();
private ContextMenuStrip strip;
private string cellErrorText;

private void dataGridView1_CellContextMenuStripNeeded(object sender,
    DataGridViewCellContextMenuStripNeededEventArgs e)
{
    cellErrorText = String.Empty;

    if (strip == null)
    {
        strip = new ContextMenuStrip();
        lookUp.Text = "Look Up";
        wholeTable.Text = "See Whole Table";
        strip.Items.Add(lookUp);
        strip.Items.Add(wholeTable);
    }
    e.ContextMenuStrip = strip;
}

private void wholeTable_Click(object sender, EventArgs e)
{
    dataGridView1.DataSource = Populate("Select * from employees", true);
}

private DataGridViewCellEventArgs theCellImHoveringOver;

private void dataGridView1_CellMouseEnter(object sender, DataGridViewCellEventArgs e)
{
    theCellImHoveringOver = e;
}

private DataGridViewCellEventArgs cellErrorLocation;

private void lookUp_Click(object sender, EventArgs e)
{
    try
    {
        dataGridView1.DataSource = Populate("Select * from employees where " +
            dataGridView1.Columns[theCellImHoveringOver.ColumnIndex].Name + " = '" +
            dataGridView1.Rows[theCellImHoveringOver.RowIndex].
            Cells[theCellImHoveringOver.ColumnIndex].Value + "'",
            true);
    }
    catch (SqlException)
    {
        cellErrorText = "Can't look this cell up";
        cellErrorLocation = theCellImHoveringOver;
    }
}

private void dataGridView1_CellErrorTextNeeded(object sender,
    DataGridViewCellErrorTextNeededEventArgs e)
{
    if (cellErrorLocation != null)
    {
        if (e.ColumnIndex == cellErrorLocation.ColumnIndex &&
            e.RowIndex == cellErrorLocation.RowIndex)
        {
            e.ErrorText = cellErrorText;
        }
    }
}

private DataTable Populate(string query, bool resetUnsharedCounter)
{
    if (resetUnsharedCounter)
    {
        ResetCounter();
    }

    // Alter the data source as necessary
    SqlDataAdapter adapter = new SqlDataAdapter(query,
        new SqlConnection("Integrated Security=SSPI;Persist Security Info=False;" +
        "Initial Catalog=Northwind;Data Source=localhost"));

    DataTable table = new DataTable();
    table.Locale = System.Globalization.CultureInfo.InvariantCulture;
    adapter.Fill(table);
    return table;
}

private Label count = new Label();
private int unsharedRowCounter;

private void ResetCounter()
{
    unsharedRowCounter = 0;
    count.Text = unsharedRowCounter.ToString();
}
Private WithEvents wholeTable As New ToolStripMenuItem()
Private WithEvents lookUp As New ToolStripMenuItem()
Private strip As ContextMenuStrip
Private cellErrorText As String

Private Sub dataGridView1_CellContextMenuStripNeeded(ByVal sender As Object, _
    ByVal e As DataGridViewCellContextMenuStripNeededEventArgs) _
    Handles dataGridView1.CellContextMenuStripNeeded

    cellErrorText = String.Empty

    If strip Is Nothing Then
        strip = New ContextMenuStrip()
        lookUp.Text = "Look Up"
        wholeTable.Text = "See Whole Table"
        strip.Items.Add(lookUp)
        strip.Items.Add(wholeTable)
    End If
    e.ContextMenuStrip = strip
End Sub

Private Sub wholeTable_Click(ByVal sender As Object, ByVal e As EventArgs) Handles wholeTable.Click
    dataGridView1.DataSource = Populate("Select * from employees", True)
End Sub

Private theCellImHoveringOver As DataGridViewCellEventArgs

Private Sub dataGridView1_CellMouseEnter(ByVal sender As Object, _
    ByVal e As DataGridViewCellEventArgs) _
    Handles dataGridView1.CellMouseEnter

    theCellImHoveringOver = e
End Sub

Private cellErrorLocation As DataGridViewCellEventArgs

Private Sub lookUp_Click(ByVal sender As Object, ByVal e As EventArgs) Handles lookUp.Click
    Try
        dataGridView1.DataSource = Populate("Select * from employees where " & _
            dataGridView1.Columns(theCellImHoveringOver.ColumnIndex).Name & " = '" & _
            dataGridView1.Rows(theCellImHoveringOver.RowIndex).Cells(theCellImHoveringOver.ColumnIndex).Value.ToString() & _
            "'", True)
    Catch ex As SqlException
        cellErrorText = "Can't look this cell up"
        cellErrorLocation = theCellImHoveringOver
    End Try
End Sub

Private Sub dataGridView1_CellErrorTextNeeded(ByVal sender As Object, _
            ByVal e As DataGridViewCellErrorTextNeededEventArgs) _
            Handles dataGridView1.CellErrorTextNeeded
    If (Not cellErrorLocation Is Nothing) Then
        If e.ColumnIndex = cellErrorLocation.ColumnIndex AndAlso _
            e.RowIndex = cellErrorLocation.RowIndex Then
            e.ErrorText = cellErrorText
        End If
    End If
End Sub

Private Function Populate(ByVal query As String, ByVal resetUnsharedCounter As Boolean) As DataTable

    If resetUnsharedCounter Then
        ResetCounter()
    End If

    ' Alter the data source as necessary
    Dim adapter As New SqlDataAdapter(query, _
        New SqlConnection("Integrated Security=SSPI;Persist Security Info=False;" & _
        "Initial Catalog=Northwind;Data Source=localhost"))

    Dim table As New DataTable()
    table.Locale = System.Globalization.CultureInfo.InvariantCulture
    adapter.Fill(table)
    Return table
End Function

Private count As New Label()
Private unsharedRowCounter As Integer

Private Sub ResetCounter()
    unsharedRowCounter = 0
    count.Text = unsharedRowCounter.ToString()
End Sub

注解

CellErrorTextNeeded事件时才会发生时DataGridView控制DataSource属性设置或其VirtualMode属性是trueThe CellErrorTextNeeded event occurs only when the DataGridView control DataSource property is set or its VirtualMode property is true. 处理CellErrorTextNeeded事件非常有用,当你想要确定具体取决于其值或状态的单元格的错误。Handling the CellErrorTextNeeded event is useful when you want to determine the error for a cell depending on its value or state.

当处理CellErrorTextNeeded事件,并指定错误文本的处理程序中的单元格中显示错误标志符号除非DataGridView.ShowCellErrors属性设置为false或单元格处于编辑模式。When you handle the CellErrorTextNeeded event and specify error text in the handler, an error glyph appears in the cell unless the DataGridView.ShowCellErrors property is set to false or the cell is in edit mode. 当用户将鼠标指针移到错误标志符号时,工具提示中将显示错误文本。When the user moves the mouse pointer over the error glyph, the error text appears in a ToolTip.

CellErrorTextNeeded时也会发生事件的值DataGridViewCell.ErrorText检索属性。The CellErrorTextNeeded event also occurs whenever the value of the DataGridViewCell.ErrorText property is retrieved.

可以使用DataGridViewCellEventArgs.RowIndexColumnIndex属性来确定的状态或值的单元格,然后使用此信息来更改或修改DataGridViewCellErrorTextNeededEventArgs.ErrorText属性。You can use the DataGridViewCellEventArgs.RowIndex and ColumnIndex property to determine the state or value of a cell, and use this information to change or modify the DataGridViewCellErrorTextNeededEventArgs.ErrorText property. 此属性使用的单元格的值初始化ErrorText属性,该事件值重写属性。This property is initialized with the value of the cell ErrorText property, which the event value overrides.

处理CellErrorTextNeeded事件时使用的大量数据,以避免设置单元格的性能损失ErrorText多个单元格的值。Handle the CellErrorTextNeeded event when working with large amounts of data to avoid the performance penalties of setting the cell ErrorText value for multiple cells. 有关详细信息,请参阅缩放 Windows 窗体 DataGridView 控件的最佳做法For more information, see Best Practices for Scaling the Windows Forms DataGridView Control.

有关如何处理事件的详细信息,请参阅处理和引发事件For more information about how to handle events, see Handling and Raising Events.

属性

ColumnIndex ColumnIndex ColumnIndex ColumnIndex

获取一个值,此值指示发生此事件的单元格的列索引。Gets a value indicating the column index of the cell that the event occurs for.

(Inherited from DataGridViewCellEventArgs)
ErrorText ErrorText ErrorText ErrorText

获取或设置选定单元格时显示的消息。Gets or sets the message that is displayed when the cell is selected.

RowIndex RowIndex RowIndex RowIndex

获取一个值,此值指示发生此事件的单元格的行索引。Gets a value indicating the row index of the cell that the event occurs for.

(Inherited from DataGridViewCellEventArgs)

方法

Equals(Object) Equals(Object) Equals(Object) Equals(Object)

确定指定的对象是否等于当前对象。Determines whether the specified object is equal to the current object.

(Inherited from Object)
GetHashCode() GetHashCode() GetHashCode() GetHashCode()

作为默认哈希函数。Serves as the default hash function.

(Inherited from Object)
GetType() GetType() GetType() GetType()

获取当前实例的 TypeGets the Type of the current instance.

(Inherited from Object)
MemberwiseClone() MemberwiseClone() MemberwiseClone() MemberwiseClone()

创建当前 Object 的浅表副本。Creates a shallow copy of the current Object.

(Inherited from Object)
ToString() ToString() ToString() ToString()

返回表示当前对象的字符串。Returns a string that represents the current object.

(Inherited from Object)

适用于

另请参阅