Question

我正在尝试编写一个创建Type t对象并分配其属性的函数。

    internal static object CreateInstanceWithParam(Type t, dynamic d)
    {
        //dynamic obj =  t.GetConstructor(new Type[] { d }).Invoke(new object[] { d });

        dynamic obj =  t.GetConstructor(new Type[] { }).Invoke(new object[] { });
        foreach (var prop in d.GetType().GetProperties(BindingFlags.Instance | BindingFlags.Public))
        {
            //prop.Name, 
            //prop.GetValue(d, null);

            // assign the properties and corresponding values to newly created object ???
        }
        return obj;
    }

然后我应该可以将它用于任何类型的类型，如

IUser user = (IUser)CreateInstanceWithParam(userType, new { UserID = 0, Name = "user abc", LoginCode = "abc", DefaultPassword = "xxxxxx" });

IUnit newUnit = (IUnit)CreateInstanceWithParam(unitType, new { ID = 3, Code = "In", Name = "Inch", Points = "72" })

如何将属性prop.Name分配给obj？

Answer 1

假设您只是想复制属性，则根本不需要dynamic：

internal static object CreateInstanceWithParam(Type type, object source)
{
    object instance = Activator.CreateInstance(type);
    foreach (var sourceProperty in d.GetType()
                                    .GetProperties(BindingFlags.Instance | 
                                                   BindingFlags.Public))
    {
        var targetProperty = type.GetProperty(sourceProperty.Name);
        // TODO: Check that the property is writable, non-static etc
        if (targetProperty != null)
        {
            object value = sourceProperty.GetValue(source);
            targetProperty.SetValue(instance, value);
        }
    }
    return instance;
}

Answer 2

实际上，在这里使用dynamic可能是坏的事情;您传入的对象是匿名类型的实例 - 不需要dynamic。特别是，dynamic成员访问与反射不同，并且您不能保证描述为dynamic的对象将从.GetType().GetProperties()返回任何有趣的内容;考虑ExpandoObject等等。

但是，FastMember（在NuGet上可用）可能很有用：

internal static object CreateInstanceWithParam(Type type, object template)
{
    TypeAccessor target = TypeAccessor.Create(type),
        source = TypeAccessor.Create(template.GetType());
    if (!target.CreateNewSupported)
            throw new InvalidOperationException("Cannot create new instance");
    if (!source.GetMembersSupported)
            throw new InvalidOperationException("Cannot enumerate members");
    object obj = target.CreateNew();
    foreach (var member in source.GetMembers())
    {
        target[obj, member.Name] = source[template, member.Name];
    }
    return obj;
}

特别是，这可以像使用反射API一样轻松地使用dynamic API，并且您通常通常看到差异。

如何将C＃动态变量属性分配给另一个动态对象？

2 个答案: