首先与Winforms和EF 4.1代码绑定

本文关键字：代码 绑定 EF Winforms | 更新日期: 2023-09-27 18:02:12

我想让Winforms组合框在新行写入数据库时自动刷新。

POCO EF class:

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

我通过BindingList像这样绑定到数据:

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";
}

这对于初始绑定很好，在表中显示当前id。随着新行添加到表中，LocalDbContext.BaseSweep.Local中的计数如预期的那样增加。但是，comboBoxSweepIds从不更新。你知道我做错了什么吗?

首先与Winforms和EF 4.1代码绑定

您需要在每次添加一行时触发一个事件并调用bind

Mark W引导我走正确的路:

//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(_sweepCollection)中使用私有BindingList<T>

在第一个数据绑定上，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";                
    }
}
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