使用 Winforms 和 EF 4.1 进行数据绑定代码优先

发布于 2024-11-20 00:12:51 字数 782 浏览 11 评论 0原文

我试图让 Winforms 组合框在新行写入数据库时自动刷新。

POCO EF 类：

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

我通过这样的 BindingList 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";
}

这对于初始绑定效果很好，显示表中的当前 Id。当新行添加到表中时，LocalDbContext.BaseSweep.Local 中的计数会按预期增加。但是，comboBoxSweepIds 永远不会更新。有什么想法我做错了吗？

原文

I'm trying to get a Winforms combobox to automatically refresh when new rows are written to our database.

POCO EF class:

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

I'm binding to the data through a BindingList like this:

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";
}

This works fine for the initial binding, shows the current Ids in the table. As new rows are added to the table, the count in LocalDbContext.BaseSweep.Local goes up as expected. However, comboBoxSweepIds never updates. Any ideas what I am doing wrong?

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柠檬心 2024-11-27 00:12:51

每次添加行时，您都需要触发事件并调用绑定。

回复收藏 0 原文

因为看清所以看轻 2024-11-27 00:12:51

Mark W 引导我找到了正确的方法：

//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

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";                

    }
}

Mark W led me the right way:

//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;
}

Use a private BindingList<T> in the form class (_sweepCollection)

On the first databind, set up the event handler:

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";                

    }
}

回复收藏 0 原文

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