我尝试使用Jon Skeets属性副本创建复印机。它适用于所有属性，但不适用于枚举。我已经尝试过多次尝试将这种方法改为枚举，但收效甚微。我想知道是否有其他人可能知道如何做到这一点。
Jon Skeets原创，我的修改与BUILDCOPIER方法中的评论分开了
对此的调用是
var result = Common.PropertyCopy<POCO>.CopyFrom(Entity);
原始Jon Skeet代码
/// <summary>
/// Generic class which copies to its target type from a source
/// type specified in the Copy method. The types are specified
/// separately to take advantage of type inference on generic
/// method arguments.
/// http://www.yoda.arachsys.com/csharp/miscutil/
/// </summary>
public static class PropertyCopy<TTarget> where TTarget : class, new()
{
/// <summary>
/// Copies all readable properties from the source to a new instance
/// of TTarget.
/// </summary>
public static TTarget CopyFrom<TSource>(TSource source) where TSource : class
{
return PropertyCopier<TSource>.Copy(source);
}
/// <summary>
/// Static class to efficiently store the compiled delegate which can
/// do the copying. We need a bit of work to ensure that exceptions are
/// appropriately propagated, as the exception is generated at type initialization
/// time, but we wish it to be thrown as an ArgumentException.
/// </summary>
private static class PropertyCopier<TSource> where TSource : class
{
private static readonly Func<TSource, TTarget> copier;
private static readonly Exception initializationException;
internal static TTarget Copy(TSource source)
{
if (initializationException != null)
{
throw initializationException;
}
if (source == null)
{
throw new ArgumentNullException("source");
}
return copier(source);
}
static PropertyCopier()
{
try
{
copier = BuildCopier();
initializationException = null;
}
catch (Exception e)
{
copier = null;
initializationException = e;
}
}
private static Func<TSource, TTarget> BuildCopier()
{
ParameterExpression sourceParameter = Expression.Parameter(typeof(TSource), "source");
var bindings = new List<MemberBinding>();
foreach (PropertyInfo sourceProperty in typeof(TSource).GetProperties())
{
if (!sourceProperty.CanRead)
{
continue;
}
PropertyInfo targetProperty = typeof(TTarget).GetProperty(sourceProperty.Name);
if (targetProperty == null)
{
throw new ArgumentException("Property " + sourceProperty.Name + " is not present and accessible in " + typeof(TTarget).FullName);
}
if (!targetProperty.CanWrite)
{
throw new ArgumentException("Property " + sourceProperty.Name + " is not writable in " + typeof(TTarget).FullName);
}
// THIS IS FALSE FOR SOURCE(INT) TARGET ENUMS
if (!targetProperty.PropertyType.IsAssignableFrom(sourceProperty.PropertyType))
{
//ADDED FOLLOWING TO HANDLE COPY FROM INT TO ENUM
/////////////////////////////////////////////////////////////////////////////////////////////////////
// Special Case because Entities are created with property as ints, not enum types
if (targetProperty.PropertyType.IsEnum && (sourceProperty.PropertyType == typeof(int)))
{
var expressionparam = Expression.Parameter(sourceProperty.PropertyType);
// cast the entity source as the enum target
var cast = Expression.Convert(expressionparam, targetProperty.PropertyType);
// add to the binding tree
bindings.Add(Expression.Bind(targetProperty, Expression.Property(cast, sourceProperty)));
continue;
}
/////////////////////////////////////////////////////////////////////////////////////////////////////
throw new ArgumentException("Property " + sourceProperty.Name + " has an incompatible type in " + typeof(TTarget).FullName);
}
Expression initializer = Expression.MemberInit(Expression.New(typeof(TTarget)), bindings);
return Expression.Lambda<Func<TSource, TTarget>>(initializer, sourceParameter).Compile();
}
}
}
枚举
public enum NotificationType
{
InAppNotificiation = 0,
EmailNotification,
SMS
}
EF生成的实体类
public class Entity
{
public int ProcessedStatus { get; set; }
public int Priority { get; set; }
public System.Guid NotifyToUserId { get; set; }
public string NotifyFrom { get; set; }
public string NotifySubject { get; set; }
public string NotifyMessageBody { get; set; }
public int NotificationType { get; set; } <-- Stored as int in DB
public virtual MercuryUser MercuryUser { get; set; } <--complex type
}
POCO课程
public class POCO
{
public int ProcessedStatus { get; set; }
public int Priority { get; set; }
public System.Guid NotifyToUserId { get; set; }
public string NotifyFrom { get; set; }
public string NotifySubject { get; set; }
public string NotifyMessageBody { get; set; }
public NotificationType NotificationType { get; set; } <-- ENUM TYPE
public MyUser MyUser { get; set; } <-- complex type
}
行
抛出异常bindings.Add(Expression.Bind(targetProperty, Expression.Property(cast, sourceProperty)));
Property＆＃39; Int32 NotificationType＆＃39;未定义类型＆＃39; Models.Enums.NotificationType
答案 0 :(得分：0)
所以我找到了这篇文章C# Using Reflection to copy base class properties并尝试了这个，有时简单只是工作......不确定为什么这个会设置枚举，也不会炸掉复杂的类型。也许就是lambda表达式如何解释对象。它不会检查是否可以为任何东西分配，特别是枚举类型，它只是根据int和属性名称设置它。如果isAssignable在尝试从int类型的sourceproperty和基础类型相同的enum类型的targetproperty进行设置时表示NO，则表示直观。如果有人能够对此有所了解，那将是很好的，现在我将使用下面列出的更简单的复制方法。低端是它不会缓存复印机，所以它必须每次都通过它。
public static T1 CopyFrom<T1, T2>(T1 obj, T2 otherObject) where T1 : class where T2 : class
{
PropertyInfo[] srcFields = otherObject.GetType().GetProperties(
BindingFlags.Instance | BindingFlags.Public | BindingFlags.GetProperty);
PropertyInfo[] destFields = obj.GetType().GetProperties(
BindingFlags.Instance | BindingFlags.Public | BindingFlags.SetProperty);
foreach (var property in srcFields)
{
var dest = destFields.FirstOrDefault(x => x.Name == property.Name);
if (dest != null && dest.CanWrite)
dest.SetValue(obj, property.GetValue(otherObject, null), null);
}
return obj;
}