筛选绑定列表，绑定不起作用 [英] Filtering a binding list, binding doesn't work

问题描述

在网格中，我使用绑定列表来绑定数据:

In a grid i use a binding list to bind data:

childBindingSource.DataSource = 
               db.Child.Local.ToBindingList()
                             .Where(child => selectedrow != null 
                                             && child.MasterID == selectedrow.ID)
                             .ToList();

或者没有过滤器:

childBindingSource.DataSource = db.Child.Local.ToBindingList();

如果我使用where表达式过滤绑定列表，则无法保存数据，但是我没有任何异常.

If I filter the binding list using a where expression, saving data doesn't work,yet i do not get any exceptions.

有什么想法吗?

用于获取子记录的行单击事件:

Row click event for getting child records:

    private void gridView1_RowClick(object sender, RowClickEventArgs e)
    {
        selectedrow = gridView1.GetFocusedRow() as Master;

        if (selectedrow != null)
        {
            int id = selectedrow.ID;
            db.Child.Where(child => child.MasterID == id).Load();
        }


        childBindingSource.DataSource = db.Child.Local.ToBindingList();

    }

推荐答案

DbSet.Local 是 ObservableCollection ，因此您可以使用 ToBindingList()，并且使用网格进行数据绑定是一项平滑的操作.

DbSet.Local is an ObservableCollection, so you can use ToBindingList(), and data binding with a grid is a smooth operation.

ToList 只会创建一个 List< T> ，并且数据绑定不会传达对列表的添加和删除(不过我希望更新能够起作用).

ToList just creates a List<T> and data binding does not communicate additions and removals from the list (I expect updates to work though).

补救措施是将上下文加载的数据过滤到 Local 列表中:

The remedy is to filter the data that the context loads into the Local list:

db.Child.Where(child => selectedrow != null 
                     && child.MasterID == selectedrow.ID).Load();
childBindingSource.DataSource = db.Child.Local.ToBindingList();

这意味着您必须为显示和更新的每组子记录使用一个新的上下文.

That means that you have to use a new context for each set of child records you show and update.

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