使用动态创建的LINQ过滤列表 [英] Filter list using a dynamically created LINQ

问题描述

我有一个Windows窗体网格，其中BindingList< myobj>已设置为数据源.现在，我想根据用户给定的条件过滤网格中的数据.该列表可以包含诸如ItemCode，Name，Price之类的列.如果用户说ItemCode ="aa"或Name ="bb"，该如何动态创建LINQ并过滤网格.

I have a windows form grid that BindingList<myobj> has set as the datasource. Now I want to filter the data in the grid according to the given condition by the user. This list can have columns like ItemCode, Name, Price. If user says ItemCode="aa" or Name ="bb" how can I dynamically create the LINQ and filter the grid.

推荐答案

我假设您的用户将输入Name = aa或ItemCode = bb等格式.在这种情况下，您需要使用类似以下内容将条目分为两部分:-

I assume your user will enter Name=aa or ItemCode=bb etc in that format. In that case you would need to split the entry into it''s 2 parts using something like this:-

string[] searchArray = txtNameSearch.Text.Split(new char[] { '=' });

然后可以使用switch语句来调用采用Predicate<>的方法.作为参数，并在调用时传递lambda表达式，如下所示:-

you could then use a switch statement to call a method that takes a Predicate<> as a parameter and pass in a lambda expression when you call it, something like this:-

private void Filter(Predicate<myClass> filter)
       {
           List<myClass> filteredClassList = (from myclass in myClassList where filter(myclass) select myclass).ToList();
           dgMyClass.DataContext = filteredClassList;
       }

switch (searchArray[0])
           {
               case "Name":
                   Filter(myclass => myclass.Name.Contains(searchArray[1]) == true);
                   break;
               case "ItemCode":
                   Filter(myclass => myclass.ItemCode.Contains(searchArray[1]) == true);
                   break;
                   //etc
           }

我使用WPF表单和DataGrid对此进行了测试，但是对于WinForms项目，它是相同的，只是将DataContext更改为DataSource

希望对您有所帮助

I used a WPF form and DataGrid to test this but it would be the same for a WinForms project, just change DataContext to DataSource

Hope this helps

请参阅此链接

http://msdn.microsoft.com/en-us/vcsharp/aa336746 [ ^ ]

see this link

http://msdn.microsoft.com/en-us/vcsharp/aa336746[^]

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