自定义组框未绑定到bindingsource

Question

我需要将a绑定GroupBox到a BindingSource,而a 又绑定到以下对象:

public class CustomerType
{
    public int Id {get; set;}
    public string Name {get; set;}
    public MemberType MemberType {get; set;}
}

public enum MemberType {Adult, Child}

我按照这个答案创建了一个自定义GroupBox.我还设置了数据绑定如下:

groupBoxMemberType.DataBindings.Add("Selected", this.bindingSource, "MemberType");

但是,在加载现有对象时,我得到以下异常:

DataBinding在列表中找不到适合所有绑定的行.

设置数据源时发生异常:

customerType = customerTypeRequest.Load(id);
bindingSource.DataSource = customerType;  //raises exception

我错过了什么？是否有替代方法可以将单选按钮绑定到数据源,特别是BindingSource？

Answer 1

这是更改后的代码：

[DefaultBindingProperty("Selected")]
public class RadioGroupBox : GroupBox
{
    #region events

    [Description("Occurs when the selected value changes.")]
    public event SelectedChangedEventHandler SelectedChanged;

    public class SelectedChangedEventArgs : EventArgs
    {
        public int Selected { get; private set; }

        internal SelectedChangedEventArgs(int selected)
        {
            this.Selected = selected;
        }
    }
    public delegate void SelectedChangedEventHandler(object sender, SelectedChangedEventArgs e);

    #endregion

    private int selected;

    [Browsable(false)]
    [Bindable(BindableSupport.Yes, BindingDirection.TwoWay)]
    [Description("The selected value associated with this control."), Category("Data")]
    public int Selected
    {
        get { return selected; }
        set
        {
            int val = 0;
            var radioButton = this.Controls.OfType<RadioButton>()
                .FirstOrDefault(radio =>
                    radio.Tag != null
                   && int.TryParse(radio.Tag.ToString(), out val) && val == value);

            if (radioButton != null)
            {
                radioButton.Checked = true;
                selected = val;
            }
        }
    }

    protected override void OnControlAdded(ControlEventArgs e)
    {
        base.OnControlAdded(e);

        var radioButton = e.Control as RadioButton;
        if (radioButton != null)
            radioButton.CheckedChanged += radioButton_CheckedChanged;
    }

    protected void OnSelectedChanged(SelectedChangedEventArgs e)
    {
        if (SelectedChanged != null)
            SelectedChanged(this, e);
    }

    private void radioButton_CheckedChanged(object sender, EventArgs e)
    {
        var radio = (RadioButton)sender;
        int val = 0;
        if (radio.Checked && radio.Tag != null
             && int.TryParse(radio.Tag.ToString(), out val))
        {
            selected = val;
            OnSelectedChanged(new SelectedChangedEventArgs(selected));
        }
    }
}

进一步将Tag属性设置为枚举的相应 int 值，您需要订阅表单中的 SelectedChanged 事件，例如：

private void radioGroupBoxMemberType_SelectedChanged(object sender, SelectedChangedEventArgs e)
{
    customerType.MemberType = (MemberType)e.Selected;
}

对这个类的改进是：

1. 继承自RadioButton并使用新的属性来代替该Tag属性。

2. 直接在控件中访问和设置 BindingSource 属性以避免订阅事件。