LINQ 过滤列表对象

Question

我有列表对象，我需要在 VB.NET 中使用 LINQ 检查逗号分隔字符串中的 id，如下所示：

dim strId as String = "1,2,3,5,"
dim myList = from objmylist where objmylist.id in (strId)

Answer 1

dim strId as String = "1,2,3,5,"
dim IDs as String() = strId.Split(",")
dim myList = from objmylist where IDs.Contains(objmylist.id) 
             select objmylist

Answer 2

dim strId as String = "1,2,3,5,"
dim myList = from objmylist where strId.split(",").Contains(objmylist.id)

未经测试，但我想应该可以解决问题。

Answer 3

如果您在 linq 中使用字符串之前将其拆分，那么您的代码就完全没问题
在 C# 中你会这样做：

string strIDs = "1,2,3,5,";
string[] arrIDs = strIDs.Split(",");
var myList = objmylist.Where(o => arrIDs.Contains(o.id));

也许你可以理解这一点并将其翻译成 VB

Answer 4

使用 C#，

int[] productList = new int[] { 1, 2, 3, 4 };

var myProducts = from p in db.Products
                 where productList.Contains(p.ProductID)
                select p;

使用 VB.NET，

Dim productList As Integer() = New Integer() {1, 2, 3, 4}

Dim myProducts = From p In db.Products Where productList.Contains(p.ProductID)

参考 使用 LINQ 创建 SQL IN 查询