使用List< SomeObject>连接DataTable. [英] Join DataTable with List<SomeObject>

问题描述

我有一个DataTable和一个对象列表.我需要返回DataTable中的所有行，其中List中的属性是某个值.列表仅用于过滤数据表(但数据表中不包含过滤器列).

I have a DataTable and a List of objects. I need to return all rows in the DataTable where a property in the List is a certain value. The List is only used for filtering the datatable (but the filter column isn't containined in the datatable).

我确定这对于LINQ是必须的.

I'm sure this must be possible with LINQ.

数据表包含:

MembershipID  Username   Password   
1              blah        blah      
2              blah        blah      
3              blah        blah      

我的列表包含:

MembershipID  Profile1   Profile2   Profile3 DifferentID   
1              blah        blah      blah    A             
2              blah        blah      blah    B             
3              blah        blah      blah    C            

我需要返回(作为数据表)-例如:对于GetUsersByDifferentID("B"):

I need to return (as a DataTable) - eg: for GetUsersByDifferentID("B"):

MembershipID  Username   Password   
2              blah        blah      
...

如果这样可以使第二张表更容易获得，那么我可以将它作为DataTable获得，但是我认为使用LINQ可以实现我所需要的.我只是无法理解魔术语法.

I could get the second table as a DataTable if that would make it easier, but I think what I need is possible with LINQ. I just can't get my head around the magic syntax.

推荐答案

您可以使用联接来实现:

You can do it using a join:

List<ListItem> listItems = //whatever
DataTable dtItems = //whatever

IEnumerable<DataRow> matchingRows = listItems
    .Join(  dtItems.AsEnumerable(),
            listItem => listItem.MembershipID,
            row => row.Field<int>("MembershipID"),
            (r,li) => new { DifferentId = li.DifferentId, Row = r })
    .Where( ji => ji.DifferentID == "B")
    .Select( ji => ji.Row);

更改where子句以使用要匹配的实际值...

Change the where clause to use the actual value you want to match...

这篇关于使用List< SomeObject>连接DataTable.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！