Question

我有一些示例代码如下：

var items = new List<object>();

var testObjectOne = new
{
    Valueone = "test1",
    ValueTwo = "test2",
    ValueThree = "test3"
};
var testObjectTwo = new
{
    Valueone = "test1",
    ValueTwo = "test2",
    ValueThree = "test3"
};
items.Add(testObjectOne);
items.Add(testObjectTwo);

foreach (var obj in items)
{
    var val = obj.Valueone;
}

但是我无法访问Valueone并得到错误：object'不包含'Valueone'的定义，并且没有扩展方法'Valueone'接受类型'object'的第一个参数可以找到（你错过了吗？使用指令或程序集引用？）

问题：我如何遍历此列表并访问ValueOne？非常感谢任何帮助或意见，谢谢

Answer 1

您可以使用反射来获取匿名类型的属性：

var items = new List<object>();

var testObjectOne = new
{
    Valueone = "test1",
    ValueTwo = "test2",
    ValueThree = "test3"
    };
var testObjectTwo = new
{
    Valueone = "test1",
    ValueTwo = "test2",
    ValueThree = "test3"
};
items.Add(testObjectOne);
items.Add(testObjectTwo);

foreach (var obj in items)
{
    var val = obj.GetType()
        .GetProperty("Valueone")
        .GetValue(obj);
}

Answer 2

另一种没有反射的解决方案是创建一个匿名对象列表，如：

var items = Enumerable.Empty<object>().Select(o=>{
                Valueone = "test1",
                ValueTwo = "test2",
                ValueThree = "test3"
            }).ToList();

修改：将对象添加到列表中

items.Add(new {
    Valueone = "Value one",
    ValueTwo = "Value two",
    ValueThree = "Value three"
});

然后在for内，语句var val = obj.Valueone将成功编译。

Answer 3

为什么不创建一个表示这些对象的类？=！它会使您的代码更加稳固，您可以避免slow/costly reflection或unsafe /bad practice dynamic杂技：

public class TempObject
{
    public string Valueone { get; set; }
    public string ValueTwo { get; set; }
    public string ValueThree { get; set; }
}

var items = new List<TempObject>();

var testObjectOne = new TempObject
{
    Valueone = "test1",
    ValueTwo = "test2",
    ValueThree = "test3"
};

items.Add(testObjectOne);

foreach (var obj in items)
{
    var val = obj.Valueone;
}

Answer 4

只需创建匿名类型的列表，而不是“List：

”

var list = new[] { new
        {
            Valueone = "test1",
            ValueTwo = "test2",
            ValueThree = "test3"
        },
        new
        {
            Valueone = "test1",
            ValueTwo = "test2",
            ValueThree = "test3"
        }
    }.ToList();

您甚至可以在列表中添加新元素：

list.Add(new {
    Valueone = "test1",
    ValueTwo = "test2",
    ValueThree = "test3"
});

现在您可以使用var轻松迭代该数组：

foreach(var e in list) ...

根本不需要反思，一切都是强类型的。

Answer 5

        //Anonymous object in C#
        var any = new { UserName = "Adel@gmail.com", Password = "P@ssw0rd" };

        //Array of anonymous objects in C#
        object[] defaultUsers = {
            new {UserName = "Adel@gmail.com", Password = "P@ssw0rd" },
            new {UserName = "Mike@gmail.com", Password = "P@ssw0rd" },
            new {UserName = "John@gmail.com", Password = "P@ssw0rd" }
        };

        //Iterate through a list of anonymous objects in C#
        foreach (var user in defaultUsers)
        {
            var userName = user.GetType().GetProperty("UserName").GetValue(user);
            var password = user.GetType().GetProperty("Password").GetValue(user);
        }

这样您可以更好地为数据建立模型

    public class DefaultUser
{
    public string UserName { get; set; }
    public string Password { get; set; }
    public string Role { get; set; }
}

然后用这种方式做，那更干净

        DefaultUser[] defaultUsers = {
            new DefaultUser() { UserName = "admin@user.com", Password = "P@ssword10", Role = "Admins"},
            new DefaultUser() { UserName = "author@user.com", Password = "P@ssword10", Role="Authors"},
            new DefaultUser() { UserName = "reader@user.com", Password = "P@ssword10", Role="Readers"}};

        foreach (DefaultUser user in defaultUsers)
        {
            var userName = user.UserName;
            var password = user.Password;
        }

如何遍历匿名对象列表？

5 个答案: