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将文本框绑定到组合框的属性。SelectedItem

textbox data-binding linq-to-sql winforms c#

Allen Rice 0x6A75616E · 技术社区 · 16 年前

这是我的密码。

public partial class TestForm : Form
{
    public DataClassesDataContext DataContext;

    public IQueryable<T> datasource;

    // Ctor
    public TestForm()
    {
    InitializeComponent();

    // L2S data context
    this.DataContext = new DataClassesDataContext();

    // Get the variable for the data source
    this.datasource = this.DataContext.Ts;

    // setup the binding for the combobox
    this.comboBox1.DataSource = this.datasource;
    this.comboBox1.DisplayMember = "Description";
    this.comboBox1.ValueMember = "Id";

    // assign the databindings of the text boxes to the selectedItem of the combo box    
    // this is where the problem is, afaik
    TId.DataBindings.Add(new Binding("Text", this.comboBox1.SelectedItem, "Id"));
    TUser.DataBindings.Add(new Binding("Text", this.comboBox1.SelectedItem, "User"));
    TDescription.DataBindings.Add(new Binding("Text", this.comboBox1.SelectedItem, "Description"));
}

但是,当我从下拉列表中选择不同的项目时,文本框不会绑定到新选择的项目,而是绑定到旧项目。

2 回复 | 直到 16 年前

Nick Larsen 16 年前

我最初的回答是错误的,诚然,我并不完全理解这里发生的一切,但我有一个解决办法,它正在发挥作用。

基本上你需要抓住 BindingManagerBase BindingContext 并使用它在每个服务器上强制执行数据绑定 SelectedItemChanged 事件

public partial class TestForm : Form
{
    public DataClassesDataContext DataContext;

    public IQueryable<T> datasource;
    private BindingManagerBase bmComboBoxSelectedItem;

    // Ctor
    public TestForm()
    {
        InitializeComponent();

        // L2S data context
        this.DataContext = new DataClassesDataContext();

        // Get the variable for the data source
        this.datasource = this.DataContext.Ts;

        // setup the binding for the combobox
        this.comboBox1.DataSource = this.datasource;
        this.comboBox1.DisplayMember = "Description";
        this.comboBox1.ValueMember = "Id";

        // assign the databindings of the text boxes to the selectedItem of the combo box    
        // this is where the problem is, afaik
        TId.DataBindings.Add(new Binding("Text", this.comboBox1, "SelectedItem.Id"));
        TUser.DataBindings.Add(new Binding("Text", this.comboBox1, "SelectedItem.User"));
        TDescription.DataBindings.Add(new Binding("Text", this.comboBox1, "SelectedItem.Description"));

        bmComboBoxSelectedItem = this.BindingContext[this.comboBox1, "SelectedItem"];
    }

    // make sure you assign this event on the forms designer or your preferred method
    private void comboBox1_SelectedIndexChanged(object sender, EventArgs e)
    {
        bmCustomers.ResumeBinding();
    }
}

MSDN article 帮助很大。

Allen Rice 0x6A75616E 16 年前

BindingSource 而不是直接依赖L2S数据上下文。绑定源使用并发管理器为您处理所有更新,而L2S不会

工作代码:

public partial class TestForm : Form
{
    public DataClassesDataContext DataContext;

    // Incorrect: public IQueryable<T> datasource;
    // Correct:
    public BindingSource TsDataSource;

    // Ctor
    public TestForm()
    {
    InitializeComponent();

    // L2S data context
    this.DataContext = new DataClassesDataContext();

    // Get the variable for the data source
    // Incorrect: this.datasource = this.DataContext.Ts;
    // Correct:
    this.TsDataSource = new BindingSource();
    this.TsDataSource.DataSource = this.DataContext.Ts;

    // setup the binding for the combobox
    this.comboBox1.DataSource = this.TsDataSource;
    this.comboBox1.DisplayMember = "Description";
    this.comboBox1.ValueMember = "Id";

    // assign the databindings of the text boxes to the selectedItem of the combo box    
    TId.DataBindings.Add(new Binding("Text", this.TsDataSource, "Id"));
    TUser.DataBindings.Add(new Binding("Text", this.TsDataSource, "User"));
    TDescription.DataBindings.Add(new Binding("Text", this.TsDataSource, "Description"));
}

source (忍不住):

通过将窗体上的控件绑定到数据通知和其他服务数据来源。这是通过使用您可以选择绑定场景将DataMember属性设置为数据中的特定列或列表来源。然后将控件绑定到数据是用调用BindingSource组件。有关BindingSource 可以简化绑定过程,请参见如何:将Windows窗体控件绑定到 DBNull数据库值以及如何: 与数据绑定一起发生。导航和正在更新数据源通过以下方法完成: 排序和排序等操作使用BindingSource进行筛选,请参阅如何:对ADO.NET数据进行排序和筛选使用Windows窗体绑定源组成部分。