Question

你有这个班级

Private Class MyClass
    Public Property propertyOne() as String
    Public Property propertyTwo() as String
    Public Property propertyN() as Integer
End Class

现在我想从lambda或linq表达式中填充一个MyClass列表，有些像这样....

    Dim myClassList as new List(Of MyClass)
    myClassList = (From lOtherList1 in MyOtherList1.GetAll()
                   join lOtherList2 in MyOterhList2.GetAll() on lOtherList1.Id Equals lOtherList2.Id
                   Select myClassList.Add(new MyClass With { .propertyOne = lOtherList1.Field1, 
                  .propertyTwo = lOtherList1.Field2,
                  .propertyN = lOtherList2.Field1 })).Tolist()

但我得到这个错误“表达式不会产生值”，我是如何制作的？

Answer 1

myClassList.Add在您的查询中是错误的部分，请按照以下步骤进行编辑：

Dim myClassList as new List(Of MyClass)
myClassList = (From lOtherList1 in MyOtherList1.GetAll()
               join lOtherList2 in MyOterhList2.GetAll() 
               on lOtherList1.Id Equals lOtherList2.Id
               Select new MyClass With 
               { 
               .propertyOne = lOtherList1.Field1, 
               .propertyTwo = lOtherList1.Field2,
               .propertyN = lOtherList2.Field1 
               })).Tolist()

Answer 2

您将执行以下操作：

myClassList = (From lOtherList1 in MyOtherList1.GetAll()
               Join lOtherList2 in MyOtherList2.GetAll()
               On lOtherList1.Id Equals lOtherList2.Id
               Select new MyClass With
               {
                   .propertyOne = lOtherList1.Field1,
                   .propertyTwo = lOtherList1.Field2,
                   .propertyN = lOtherList2.Field1
               }).ToList()

您几乎拥有正确的代码。您只需要移除对myClassList.Add()的调用。

将列表linq表达式转换为定义列表类

2 个答案: