如何将动态列表 List<object> 转换为对象列表 List<Customer>

Question

我正在尝试将我的动态列表 List<object> 转换为 List<Customer>。 动态列表共有 10 个属性（Id、Name、PhoneNo、Address、SecodaryPhone、Email 等），Customer 类只有 Id、Name 和 PhoneNo。 我想转换列表，以便它将复制具有映射属性的列表。

我不能使用动态属性的名称，因为这可以像存储其他类型一样使用任何其他类型，比如产品。

Answer 1

安装 AutoMapper NuGet 包。然后你可以像这样投射你的列表：

class Program
{
    static void Main(string[] args)
    {
        var config = new MapperConfiguration(cfg => { });
        var mapper = config.CreateMapper();

        dynamic person = new { Name = "John", Id = 10 };

        var people = new List<dynamic>() { person };
        var cusomters = people.Select(p => mapper.Map<Customer>(p)).ToList();
    }
}

class Customer
{
    public string Name { get; set; }
}

编辑

或者，如果您不想使用 AutoMapper，您可以尝试以下方法：

    class Program
{
    static void Main(string[] args)
    {
        dynamic people = new { Name = "John", Id = 10 };

        var list = new List<dynamic>() { people };
        var result = list.Select(p => new Customer(p)).ToList();
    }
}

class Customer
{
    public string Name { get; set; }

    public Customer(dynamic arg)
    {
        Name = arg.Name;
    }
}

Answer 2

使用一些扩展来简化MemberInfo 的使用：

// ***
// *** Type Extensions
// ***
public static List<MemberInfo> GetPropertiesOrFields(this Type t, BindingFlags bf = BindingFlags.Public | BindingFlags.Instance) =>
    t.GetMembers(bf).Where(mi => mi.MemberType == MemberTypes.Field | mi.MemberType == MemberTypes.Property).ToList();

// ***
// *** MemberInfo Extensions
// ***
public static object GetValue(this MemberInfo member, object srcObject) {
    switch (member) {
        case FieldInfo mfi:
            return mfi.GetValue(srcObject);
        case PropertyInfo mpi:
            return mpi.GetValue(srcObject);
        default:
            throw new ArgumentException("MemberInfo must be of type FieldInfo or PropertyInfo", nameof(member));
    }
}
public static T GetValue<T>(this MemberInfo member, object srcObject) => (T)member.GetValue(srcObject);

public static void SetValue<T>(this MemberInfo member, object destObject, T value) {
    switch (member) {
        case FieldInfo mfi:
            mfi.SetValue(destObject, value);
            break;
        case PropertyInfo mpi:
            mpi.SetValue(destObject, value);
            break;
        default:
            throw new ArgumentException("MemberInfo must be of type FieldInfo or PropertyInfo", nameof(member));
    }
}

您可以使用此扩展将匹配的对象成员值复制到另一种类型：

// Convert any object to another Type by copying over common properties or fields
public static T ToType<T>(this object obj) where T : new() {
    var ansObj = new T();
    var ansFields = typeof(T).GetPropertiesOrFields().ToDictionary(pf => pf.Name);

    foreach (var prop in obj.GetType().GetPropertiesOrFields())
        if (ansFields.TryGetValue(prop.Name, out var destpf))
            destpf.SetValue(ansObj, prop.GetValue(obj));

    return ansObj;
}

所以你的最终结果是：

var ans = sourceList.Select(m => m.ToType<Customer>()).ToList();

但我认为使用接口并拥有一个通用的基本接口会更好：

interface IIDBase {
    int Id { get; set; }
    string Name { get; set; }
    string PhoneNo { get; set; }
}

public class Customer {
    public int Id { get; set; }
    public string Name { get; set; }
    public string PhoneNo { get; set; }
}

public class Products : IIDBase {
    public int Id { get; set; }
    public string Name { get; set; }
    public string PhoneNo { get; set; }
    // ...
}

然后您只需转换为 List<IIDBase>:

var ans = sourceList.Cast<IIDBase>().Select(m => new Customer {
              Id = m.Id,
              Name = m.Name,
              PhoneNo = m.PhoneNo
          });

Answer 3

如果您可以使用dynamic，这应该可以工作。

var list = new List<object>(new [] 
{
    new DynamicObject {Id = $"{1}", Name = $"Name{1}", PhoneNo = $"555-000{1}-1234"},
    new DynamicObject {Id = $"{2}", Name = $"Name{2}", PhoneNo = $"555-000{2}-1234"},
    new DynamicObject {Id = $"{3}", Name = $"Name{3}", PhoneNo = $"555-000{3}-1234"},
});
var customers = ((IEnumerable<dynamic>)list).Select(x => new Customer{ Id = x.Id, Name = x.Name, PhoneNo = x.PhoneNo}).ToArray();
Customer customer = customers.First();



class DynamicObject
{
    public string Id { get; set; }
    public string Name { get; set; }
    public string PhoneNo { get; set; }
    public string Address { get; set; }
    public string SecodaryPhone { get; set; }
    public string Email { get; set; }
}

class Customer
{
    public string Id { get; set; }
    public string Name { get; set; }
    public string PhoneNo { get; set; }
}