c# - Reflection.TargetException问题

Question

我希望 Employee 的 EmployeeNumber 属性仅由数据库设置，但我需要能够设置单元测试的值。这就是为什么我在下面制作了帮助程序代码。

有人可以帮我排查和解决这个问题吗？

干杯，
贝瑞尔

助手代码

public static void SetEmployeeNumberFor(Employee employee, EmployeeNumber employeeNumber)
    {
        var empNumberProperty = employee.GetType().GetProperty("EmployeeNumber", BindingFlags.Public | BindingFlags.Instance);

        Check.Invariant(empNumberProperty != null);
        Check.Invariant(empNumberProperty.PropertyType.Equals(typeof(EmployeeNumber)));

        empNumberProperty.SetValue(empNumberProperty, employeeNumber, null);
    }

完全异常

System.Reflection.TargetException : Object does not match target type.
at System.Reflection.RuntimeMethodInfo.CheckConsistency(Object target)
at System.Reflection.RuntimeMethodInfo.Invoke(Object obj, BindingFlags invokeAttr, Binder binder, Object[] parameters, CultureInfo culture, Boolean skipVisibilityChecks)
at System.Reflection.RuntimeMethodInfo.Invoke(Object obj, BindingFlags invokeAttr, Binder binder, Object[] parameters, CultureInfo culture)
at System.Reflection.RuntimePropertyInfo.SetValue(Object obj, Object value, BindingFlags invokeAttr, Binder binder, Object[] index, CultureInfo culture)
at System.Reflection.RuntimePropertyInfo.SetValue(Object obj, Object value, Object[] index)
TestableEmployee.cs(36,0): at Smack.ConstructionAdmin.TestingSupport.ResourceHelper.SetEmployeeNumberFor(Employee employee, EmployeeNumber employeeNumber)
TestableEmployee.cs(47,0): at Smack.ConstructionAdmin.TestingSupport.ResourceHelperTests.SetEmployeeNumberFor()

EmployeeNumber 属性代码

    public virtual EmployeeNumber EmployeeNumber {
        get { return _employeeNumber; } 
        protected set {
            _employeeNumber = value;
            //base.BusinessId = _employeeNumber;
        }
    }
    private EmployeeNumber _employeeNumber;

Answer 1

试试用这个代替:

empNumberProperty.SetValue(employee, employeeNumber, null);

问题是 SetValue 的第一个参数是您尝试修改的对象。

同时查看 MSDN Documentation ，我还注意到，如果“非法尝试访问类中的私有(private)或 protected 方法”，此方法可能会抛出 MethodAccessException，这似乎适用于这种情况。在备注部分，出现此通知:

Starting with the .NET Framework version 2.0 Service Pack 1, this method can be used to access non-public members if the caller has been granted ReflectionPermission with the ReflectionPermissionFlag.RestrictedMemberAccess flag and if the grant set of the non-public members is restricted to the caller’s grant set, or a subset thereof. To use this functionality, your application should target the .NET Framework version 3.5 or later.

或者，您可以尝试使用 GetSetMethod(bool) ，但这仍将受到相同的安全限制。

empNumberProperty.GetSetMethod(true).Invoke(employee, new[] { employeeNumber });