Question

第一个表达式传递，但第二个表达式没有..错误是

AmbigiouseMatchExeption

任何人都知道为什么一个类的字段和属性表现不一致？怎么解决？

Answer 1

Expression.PropertyOrField方法使用GetProperty(string,BindingFlags)来查找属性。此函数似乎不实现名称隐藏，而相应的GetField(string,BindingFlags)实现。

您需要使用GetProperties并选择所需的属性，然后使用Expression.Property的{{1}}重载。

Answer 2

对于那些感兴趣的人...
它在线失败

GetType(Inherited(Of String)).GetProperty("Prop1")

Imports System.Linq.Expressions
Imports NUnit.Framework

<TestFixture> Public Class ExpressionTEst

<Test> Public Sub GetOvrriddenProperyInExpression()

    Dim ex = Expression.PropertyOrField(Expression.Constant(Nothing, GetType(Inherited(Of String))), "field1")
    Dim ex2 = Expression.PropertyOrField(Expression.Constant(Nothing, GetType(Inherited(Of String))), "t2")

    GetType(Inherited(Of String)).GetField("field1")
    GetType(Inherited(Of String)).GetProperty("Prop1")

    Dim ex3 = Expression.PropertyOrField(Expression.Constant(Nothing, GetType(Inherited(Of String))), "Prop1")

End Sub

Public Class Base
    Public field1 As Object
    Public Property Prop1 As Object

    Public Overridable Property t2 As String
End Class

Public Class Inherited(Of T)
    Inherits Base

    Public Overrides Property t2 As String
        Get
            Return MyBase.t2
        End Get
        Set(value As String)
            MyBase.t2 = value
        End Set
    End Property

    Public Shadows field1 As T
    Public Shadows Property Prop1 As T

End Class

结束班

因为@NetMage和@IvanStoev说GetField与GetProperty的不一致

这段代码解决了它......有点

Expression memberValue = null;
            if (m.MemberType == MemberTypes.Property)
            {
                PropertyInfo propInfo = null;
                foreach(var p in m.DeclaringType.GetProperties())
                {
                    if (p.Name == m.Name)
                    {
                        //Just pick the first one. 
                        propInfo = p;
                        break;
                    }
                }
                memberValue = Expression.Property(Expression.Convert(valueObject, objType), propInfo);
            }
            else
            {
                memberValue = Expression.Field(Expression.Convert(valueObject, objType), m.Name);
            }

Expression.PropertyOrField中的行为不一致

2 个答案: