在Bindinglist上过滤 [英] filtering on a Bindinglist

问题描述

你好！

我正在使用vb.net 2017和实体框架6

I'm using vb.net 2017 and entity Framework 6

我有一个学生桌，我也是有一个在设计中配置的Bindingosurce， 绑定到此绑定源的datagridview。

I have a Students Table , also I have a Bindingosurce that is configured in design,  and a datagridview bound to this bindingsource.

我想首先加载所有学生，并在使用本地数据后使用我需要的数据填充bindingsource：

I want to first load all students , and after work with local data to fill the bindingsource with the data that I needs :

我有这段代码：

Context.Myobjs1.Students.Load()
Mybindingsource1.Datasource=Context.obj1s.Local.TobindingList

如果我使用此代码一切正常，我可以在gridview上显示数据，我可以在gridview上添加，删除或修改数据并保存它们。

If I use this code everything works ok , I can display data on gridview , I can add , delete or modify data on gridview and save them.

但问题是，根据用户的选择，我想在bindingsource上过滤数据，所以我不想要在我的第二行代码上使用的所有本地数据，但是例如我想要所有具有nr> 1的研究。

But the problems is that depending on user choice , I want to filter data on bindingsource , so I don't want all the local data that is used on my second line of code ,but for example I want all studnets that have nr>1.

但是如果我使用：

Mybindingsource1.Datasource=Context.obj1s.Local.TobindingList.Where(Function(t2) t2.nr>1).Tolist

数据在datagridview中正确显示，但是当我添加或删除时某些东西，更改不会保存。

The data is displayed correctly in datagridview , but when I add or delete something , the changes are not saved .

如果我尝试使用：

Mybindingsource1.Datasource=Context.obj1s.Local.Where(Function(t2) t2.nr>1).TobindingList

在这种情况下没有tobindingList。

There's no tobindingList in this case.

我知道我可以在从数据库加载时过滤数据，但事实并非如此，因为我想从数据库加载所有数据，之后我想使用本地数据。

I know that I can filter the data when loading from database , but this is not the case because I want to load all data from database , and after I want to work with local data.

那我该怎么办？

谢谢！

推荐答案

您好dcode25，

Hi dcode25,

以下主题提供了有关如何添加/删除/编辑的示例代码/通过BindingSource过滤以供参考。

The following thread provide a sample code about how to Add/Remove/Edit/Filter via BindingSource for your reference.

#Filter related。

#Filter related.

Private Sub FilterButton_Click(ByVal sender As Object, ByVal e As EventArgs)
    If String.IsNullOrEmpty(Me.FilterTextBox.Text) Then
        Me.Mybindingsource1.DataSource = db.obj1s.Local.ToBindingList()
    Else
        Dim filteredData = db.obj1s.Local.Where(Function(t2) t2.nr>1)
        Me.Mybindingsource1.DataSource = filteredData
    End If
End Sub

https://stackoverflow.com/questions/35977042/how-to-filter-data-using -entity-framework-in-a-way-datagridview-be-editable / 35978408

此外，您还可以参考以下主题，该主题使用  BindingListView

In addition, you could also refer to the following thread, which use BindingListView

https://stackoverflow.com/questions/23309112/ef-in-winforms-how-to-filter-data-in-bindingsource-dgw-loc al-todingdinglist

祝你好运，

张龙

这篇关于在Bindinglist上过滤的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！