在 Windows 窗体中使用数据绑定时,经常有多个控件被绑定到同一数据源。在某些情况下,可能有必要采取额外步骤,以确保控件的绑定属性彼此之间保持同步,并且与数据源保持同步。在两种情况下,这些步骤是必要的:
如果数据源未实现 IBindingList,并因此生成类型 ItemChanged 的 ListChanged 事件。
如果数据源实现 IEditableObject。
在前一种情况下,可使用 BindingSource 将数据源绑定到控件。在后一种情况下,应使用 BindingSource 并处理 BindingComplete 事件,然后对关联的 BindingManagerBase 调用 EndCurrentEdit。
示例
下面的代码示例演示如何使用 BindingSource 组件,将三个控件(两个文本框控件和一个 DataGridView 控件)绑定到 DataSet 中的同一列。该示例演示如何处理 BindingComplete 事件,并确保当一个文本框的文本值更改时,会用正确的值更新其他文本框和 DataGridView 控件。
该示例使用 BindingSource 来绑定数据源和控件。或者,可以直接将控件绑定到数据源,并从窗体的 BindingContext 检索用于绑定的 BindingManagerBase,然后为 BindingManagerBase 处理 BindingComplete 事件。有关如何进行此操作的示例,请参见 BindingManagerBase 的 BindingComplete 事件的相关帮助页。
// Declare the controls to be used.
private BindingSource bindingSource1;
private TextBox textBox1;
private TextBox textBox2;
private DataGridView dataGridView1;
private void InitializeControlsAndDataSource()
{
// Initialize the controls and set location, size and
// other basic properties.
this.dataGridView1 = new DataGridView();
this.bindingSource1 = new BindingSource();
this.textBox1 = new TextBox();
this.textBox2 = new TextBox();
this.dataGridView1.ColumnHeadersHeightSizeMode =
DataGridViewColumnHeadersHeightSizeMode.AutoSize;
this.dataGridView1.Dock = DockStyle.Top;
this.dataGridView1.Location = new Point(0, 0);
this.dataGridView1.Size = new Size(292, 150);
this.textBox1.Location = new Point(132, 156);
this.textBox1.Size = new Size(100, 20);
this.textBox2.Location = new Point(12, 156);
this.textBox2.Size = new Size(100, 20);
this.ClientSize = new Size(292, 266);
this.Controls.Add(this.textBox2);
this.Controls.Add(this.textBox1);
this.Controls.Add(this.dataGridView1);
// Declare the DataSet and add a table and column.
DataSet set1 = new DataSet();
set1.Tables.Add("Menu");
set1.Tables[0].Columns.Add("Beverages");
// Add some rows to the table.
set1.Tables[0].Rows.Add("coffee");
set1.Tables[0].Rows.Add("tea");
set1.Tables[0].Rows.Add("hot chocolate");
set1.Tables[0].Rows.Add("milk");
set1.Tables[0].Rows.Add("orange juice");
// Set the data source to the DataSet.
bindingSource1.DataSource = set1;
//Set the DataMember to the Menu table.
bindingSource1.DataMember = "Menu";
// Add the control data bindings.
dataGridView1.DataSource = bindingSource1;
textBox1.DataBindings.Add("Text", bindingSource1,
"Beverages", true, DataSourceUpdateMode.OnPropertyChanged);
textBox2.DataBindings.Add("Text", bindingSource1,
"Beverages", true, DataSourceUpdateMode.OnPropertyChanged);
bindingSource1.BindingComplete +=
new BindingCompleteEventHandler(bindingSource1_BindingComplete);
}
private void bindingSource1_BindingComplete(object sender, BindingCompleteEventArgs e)
{
// Check if the data source has been updated, and that no error has occured.
if (e.BindingCompleteContext ==
BindingCompleteContext.DataSourceUpdate && e.Exception == null)
// If not, end the current edit.
e.Binding.BindingManagerBase.EndCurrentEdit();
}