Question

我正在尝试让Winforms组合框在新行写入数据库时自动刷新。

POCO EF课程：

public class BaseSweep 
{
    public int BaseSweepId { get; set; }
    //stuff removed for clarity
}

我通过像这样的BindingList绑定数据：

public BindingList<BaseSweep> TopSweeps()
{
    LocalDbContext.BaseSweep.Load();
    return LocalDbContext.BaseSweep.Local.ToBindingList();                     

}

private void BindSweepList() //called in Form_Load
{
    comboBoxSweepIds.DataSource = _dataAccess.TopSweeps();
    comboBoxSweepIds.DisplayMember = "BaseSweepId";
    comboBoxSweepIds.ValueMember = "BaseSweepId";
}

这适用于初始绑定，显示表中的当前ID。随着新行添加到表中，LocalDbContext.BaseSweep.Local中的计数会按预期上升。但是，comboBoxSweepIds永远不会更新。我有什么想法吗？

Answer 1

您需要触发事件并在每次添加行时调用bind。

Answer 2

Mark W以正确的方式领导我：

//put an event handler on the collection
public void CollectionChanged<T>(System.Collections.Specialized.NotifyCollectionChangedEventHandler eventHandler) where T : class
{
     LocalDbContext.Set<T>().Local.CollectionChanged += eventHandler;
}

在表单类（BindingList<T>）

中使用私有_sweepCollection

在第一个数据绑定中，设置事件处理程序：

private void BindSweepList()
{            
    _sweepCollection = _dataAccess.TopSweeps();
    _dataAccess.CollectionChanged<CableSweepDebug>(new System.Collections.Specialized.NotifyCollectionChangedEventHandler(Local_CollectionChanged));

    UpdateSweepsData();
}

private void Local_CollectionChanged(object sender, System.Collections.Specialized.NotifyCollectionChangedEventArgs e)
{
     UpdateSweepsData();
}

private void UpdateSweepsData()
{
    if (comboBoxSweepIds.InvokeRequired)
    {
        Invoke(new UpdateSweepCount(UpdateSweepsData));
    }
    else
    {
        var tmpBind = _sweepCollection.OrderByDescending(t => t.BaseSweepId).Take(100);

        comboBoxSweepIds.DataSource = null;
        comboBoxSweepIds.DataSource = tmpBind.ToList() ;
        comboBoxSweepIds.DisplayMember = "BaseSweepId";
        comboBoxSweepIds.ValueMember = "BaseSweepId";                

    }
}

首先使用Winforms和EF 4.1代码进行数据绑定

2 个答案: