vb.net 遍历类属性

Iterate through class properties

提问by donL

I have a VB.NET class called ticket that has several public properties of type 'field'. I would like to have a way that I can iterate through all of these properties (with a for each) and perform a specific task on each of them. I thought that maybe the best way was to create a list(Of field) and fill the list with the 'field' properties of that class. What I don't know how to do is get the properties into the list dynamically so that if I add properties in the future I don't have to type them into the list manually. Any thoughts on how I might do this? I tried searching for and found some examples of using reflection but I could only figure out how to get at the name of the property and not the property itself.

我有一个名为 ticket 的 VB.NET 类，它具有多个“字段”类型的公共属性。我想有一种方法可以遍历所有这些属性（每个属性都有一个）并对每个属性执行特定任务。我认为也许最好的方法是创建一个列表（字段）并用该类的“字段”属性填充列表。我不知道如何做的是将属性动态添加到列表中，这样如果我将来添加属性，我就不必手动将它们键入到列表中。关于我如何做到这一点的任何想法？我尝试搜索并找到了一些使用反射的示例，但我只能弄清楚如何获取属性的名称，而不是属性本身。

Here is an example of a class:

下面是一个类的例子：

Public Class ticket
    Public Property location As New field
    Public Property user As New field
    Public Property callType As New field
    Public Property dateOfCall As New field
    Public Property tech As New field
    Public Property description As New field

    Public Property myFields As New List(Of field)

'What if field had a property of value and I wanted to increment all of the fields    in this class by one

Public Sub plusOne()
    For Each x As field In myFields()
        x.value += 1
    Next
End Sub

End Class

回答by Seth Flowers

You want to use Reflection, which just means inspecting the types in an assembly. You can do this via the System.Reflectionnamespace.

您想使用Reflection，这意味着检查程序集中的类型。您可以通过System.Reflection命名空间执行此操作。

See the following article on the msdn magazine for examples of reflection in VB.Net: http://msdn.microsoft.com/en-us/magazine/cc163750.aspx

有关 VB.Net 中的反射示例，请参阅 msdn 杂志上的以下文章：http: //msdn.microsoft.com/en-us/magazine/cc163750.aspx

An example of iterating over the members of a type in that article is as follows:

迭代该文章中类型的成员的示例如下：

Dim t As Type = GetType(AcmeCorp.BusinessLogic.Customer)
For Each member As MemberInfo In t.GetMembers
  Console.WriteLine(member.Name)
Next

回答by LukeHennerley

Again as the previous answer - you would use reflection. To call as an example Addon a List(Of T)I would do this.

再次作为上一个答案-您将使用反射。以 a 为例Add，List(Of T)我会这样做。

Public Class Test
  Public Property SomeList As List(Of String)
End Class

Then use the following code to call add on a List(Of String)

然后使用以下代码调用 add on a List(Of String)

Dim pi As PropertyInfo = GetType(Test).GetProperty("SomeList")
Dim mi As MethodInfo = GetType(List(Of String)).GetMethod("Add")
Dim t As New Test()
t.SomeList = New List(Of String)
mi.Invoke(pi.GetValue(t, Nothing), New Object() {"Added through reflection"})

回答by Stuart Blackler

As the previous answers have said, you need to use System.Reflection to get the properties of the class. Then check the property is the type that you want.

正如前面的答案所说，您需要使用 System.Reflection 来获取类的属性。然后检查属性是您想要的类型。

Hopefully this should give you what you want. If you run the code you will see that it only takes the properties of the specified type. If you want to have all properties, remove the where statement on the for each loop.

希望这应该给你你想要的。如果您运行代码，您将看到它只采用指定类型的属性。如果您想拥有所有属性，请删除 for each 循环上的 where 语句。

Imports System.Reflection

Module Module1

Sub Main()

    ' Create a list to hold your properties
    Dim myList As New List(Of MyProperty)

    ' check each property for its type using the where statement below. Change integer to "Field" in your case
    For Each el In GetType(Test).GetProperties.Where(Function(p) p.PropertyType = GetType(Integer))
        ' add each matching property to the list
        myList.Add(New MyProperty With {.Name = el.Name, .GetMethod = el.GetGetMethod(), .SetMethod = el.GetSetMethod()})
        Console.WriteLine(el.Name & " has been added to myList")
    Next

    Console.Read()
End Sub

Public Class MyProperty
    Public Property Name As String
    Public Property GetMethod As MethodInfo
    Public Property SetMethod As MethodInfo
End Class

Public Class Test
    Private var1 As String
    Private var2 As String
    Private var3 As String
    Private var4 As String

    Public Property myInt1 As Integer
    Public Property myInt2 As Integer
    Public Property myInt3 As Integer
    Public Property myInt4 As Integer
End Class
End Module

Hope that helps

希望有帮助