C# 自动将一个对象的属性值应用到另一个相同类型的对象？

Apply properties values from one object to another of the same type automatically?

提问by eKek0

Given 2 objects A and B of type T, I want to assign the properties' values in A to the same properties in B without doing an explicit assignment for each property.

给定 2 个 T 类型的对象 A 和 B，我想将 A 中的属性值分配给 B 中的相同属性，而不对每个属性进行显式分配。

I want to save code like this:

我想保存这样的代码：

b.Nombre = a.Nombre;
b.Descripcion = a.Descripcion;
b.Imagen = a.Imagen;
b.Activo = a.Activo;

doing something like

做类似的事情

a.ApplyProperties(b);

Is it possible?

是否可以？

采纳答案by Jon Skeet

I have a type in MiscUtilcalled PropertyCopywhich does something similar - although it creates a new instance of the target type and copies the properties into that.

我在MiscUtil调用中有一个类型，PropertyCopy它执行类似的操作 - 尽管它创建了目标类型的新实例并将属性复制到该实例中。

It doesn't require the types to be the same - it just copies all the readable properties from the "source" type to the "target" type. Of course if the types are the same, that's more likely to work :) It's a shallow copy, btw.

它不要求类型相同——它只是将所有可读属性从“源”类型复制到“目标”类型。当然，如果类型相同，那更有可能起作用:) 这是一个浅拷贝，顺便说一句。

In the code block at the bottom of this answer, I've extended the capabilities of the class. To copy from one instance to another, it uses simple PropertyInfovalues at execution time - this is slower than using an expression tree, but the alternative would be to write a dynamic method, which I'm not too hot on. If performance is absolutely critical for you, let me know and I'll see what I can do. To use the method, write something like:

在此答案底部的代码块中，我扩展了该类的功能。为了从一个实例复制到另一个实例，它PropertyInfo在执行时使用简单的值——这比使用表达式树慢，但另一种方法是编写一个动态方法，我不太热衷。如果性能对您来说绝对至关重要，请告诉我，我会看看我能做些什么。要使用该方法，请编写如下内容：

MyType instance1 = new MyType();
// Do stuff
MyType instance2 = new MyType();
// Do stuff

PropertyCopy.Copy(instance1, instance2);

(where Copyis a generic method called using type inference).

（其中Copy是使用类型推断调用的泛型方法）。

I'm not really ready to do a full MiscUtil release, but here's the updated code, including comments. I'm not going to rewrap them for the SO editor - just copy the whole chunk.

我还没有准备好发布完整的 MiscUtil，但这里是更新后的代码，包括注释。我不会为 SO 编辑器重新包装它们 - 只需复制整个块。

(I'd also probably redesign the API a bit in terms of naming if I were starting from scratch, but I don't want to break existing users...)

（如果我从头开始，我也可能会在命名方面重新设计 API，但我不想破坏现有用户......）

#if DOTNET35
using System;
using System.Collections.Generic;
using System.Linq.Expressions;
using System.Reflection;

namespace MiscUtil.Reflection
{
    /// <summary>
    /// Non-generic class allowing properties to be copied from one instance
    /// to another existing instance of a potentially different type.
    /// </summary>
    public static class PropertyCopy
    {
        /// <summary>
        /// Copies all public, readable properties from the source object to the
        /// target. The target type does not have to have a parameterless constructor,
        /// as no new instance needs to be created.
        /// </summary>
        /// <remarks>Only the properties of the source and target types themselves
        /// are taken into account, regardless of the actual types of the arguments.</remarks>
        /// <typeparam name="TSource">Type of the source</typeparam>
        /// <typeparam name="TTarget">Type of the target</typeparam>
        /// <param name="source">Source to copy properties from</param>
        /// <param name="target">Target to copy properties to</param>
        public static void Copy<TSource, TTarget>(TSource source, TTarget target)
            where TSource : class
            where TTarget : class
        {
            PropertyCopier<TSource, TTarget>.Copy(source, target);
        }
    }

    /// <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.
    /// </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, TTarget>.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.
    /// Note that this type we do not have a constructor constraint on TTarget, because
    /// we only use the constructor when we use the form which creates a new instance.
    /// </summary>
    internal static class PropertyCopier<TSource, TTarget>
    {
        /// <summary>
        /// Delegate to create a new instance of the target type given an instance of the
        /// source type. This is a single delegate from an expression tree.
        /// </summary>
        private static readonly Func<TSource, TTarget> creator;

        /// <summary>
        /// List of properties to grab values from. The corresponding targetProperties 
        /// list contains the same properties in the target type. Unfortunately we can't
        /// use expression trees to do this, because we basically need a sequence of statements.
        /// We could build a DynamicMethod, but that's significantly more work :) Please mail
        /// me if you really need this...
        /// </summary>
        private static readonly List<PropertyInfo> sourceProperties = new List<PropertyInfo>();
        private static readonly List<PropertyInfo> targetProperties = new List<PropertyInfo>();
        private static readonly Exception initializationException;

        internal static TTarget Copy(TSource source)
        {
            if (initializationException != null)
            {
                throw initializationException;
            }
            if (source == null)
            {
                throw new ArgumentNullException("source");
            }
            return creator(source);
        }

        internal static void Copy(TSource source, TTarget target)
        {
            if (initializationException != null)
            {
                throw initializationException;
            }
            if (source == null)
            {
                throw new ArgumentNullException("source");
            }
            for (int i = 0; i < sourceProperties.Count; i++)
            {
                targetProperties[i].SetValue(target, sourceProperties[i].GetValue(source, null), null);
            }

        }

        static PropertyCopier()
        {
            try
            {
                creator = BuildCreator();
                initializationException = null;
            }
            catch (Exception e)
            {
                creator = null;
                initializationException = e;
            }
        }

        private static Func<TSource, TTarget> BuildCreator()
        {
            ParameterExpression sourceParameter = Expression.Parameter(typeof(TSource), "source");
            var bindings = new List<MemberBinding>();
            foreach (PropertyInfo sourceProperty in typeof(TSource).GetProperties(BindingFlags.Public | BindingFlags.Instance))
            {
                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);
                }
                if ((targetProperty.GetSetMethod().Attributes & MethodAttributes.Static) != 0)
                {
                    throw new ArgumentException("Property " + sourceProperty.Name + " is static in " + typeof(TTarget).FullName);
                }
                if (!targetProperty.PropertyType.IsAssignableFrom(sourceProperty.PropertyType))
                {
                    throw new ArgumentException("Property " + sourceProperty.Name + " has an incompatible type in " + typeof(TTarget).FullName);
                }
                bindings.Add(Expression.Bind(targetProperty, Expression.Property(sourceParameter, sourceProperty)));
                sourceProperties.Add(sourceProperty);
                targetProperties.Add(targetProperty);
            }
            Expression initializer = Expression.MemberInit(Expression.New(typeof(TTarget)), bindings);
            return Expression.Lambda<Func<TSource, TTarget>>(initializer, sourceParameter).Compile();
        }
    }
}
#endif

回答by Cade Roux

There's ICloneableand object.MemberwiseClone(shallow copy) (these create a whole new object, so might not meet your requirements).

有ICloneable和object.MemberwiseClone（浅拷贝）（这些创建了一个全新的对象，因此可能无法满足您的要求）。

You could use reflection to do it yourself (inherit from a base class so you don't have to re-implement).

您可以使用反射自己完成（从基类继承，因此您不必重新实现）。

Or you could code generate it.

或者你可以代码生成它。

回答by jrista

If you want something like ApplyProperties, you could write an extension method on Object which would do what you need. Just realize that such an extension method wouldn't be "pure", or side-effect free. But if you need the capability, its a way to accomplish it.

如果你想要像 ApplyProperties 这样的东西，你可以在 Object 上编写一个扩展方法，它可以满足你的需求。只要意识到这样的扩展方法不会是“纯粹的”，或者没有副作用。但是如果你需要这种能力，它是一种实现它的方法。

回答by Andrija

You can use serialization to deep clone the object:

您可以使用序列化来深度克隆对象：

public static T DeepClone<T>(this T objectToClone) where T: BaseClass
{
    BinaryFormatter bFormatter = new BinaryFormatter();
    MemoryStream stream = new MemoryStream();
    bFormatter.Serialize(stream, objectToClone);
    stream.Seek(0, SeekOrigin.Begin);
    T clonedObject = (T)bFormatter.Deserialize(stream);
    return clonedObject;
}

Classes would just have to be marked Serializable of course.

当然，类只需要标记为可序列化。

回答by Steve

You might try something like this....

你可以尝试这样的事情......

MyType destination = new MyType();
MyType source = new MyType();

// Iterate the Properties of the destination instance and 
// populate them from their source counterparts

PropertyInfo[] destinationProperties = destination.GetType().GetProperties();
foreach (PropertyInfo destinationPI in destinationProperties)
{
    PropertyInfo sourcePI = source.GetType().GetProperty(destinationPI.Name);

    destinationPI.SetValue(destination,
                           sourcePI.GetValue(source, null), 
                           null);
}

回答by Daniel

Building off of Steve's method, I went with the extension method approach. This uses my base class as type but should be useable even using object as the param types. Works great for my uses.

基于 Steve 的方法，我采用了扩展方法方法。这使用我的基类作为类型，但即使使用 object 作为参数类型也应该可用。非常适合我的用途。

using System.Reflection;
//*Namespace Here*
public static class Ext
{
    public static void CopyProperties(this EntityBase source, EntityBase destination)
    {
        // Iterate the Properties of the destination instance and  
        // populate them from their source counterparts  
        PropertyInfo[] destinationProperties = destination.GetType().GetProperties(); 
        foreach (PropertyInfo destinationPi in destinationProperties)
        {
            PropertyInfo sourcePi = source.GetType().GetProperty(destinationPi.Name);     
            destinationPi.SetValue(destination, sourcePi.GetValue(source, null), null);
        } 
    }
}

Usage looks like this:

用法如下所示：

item1.CopyProperties(item2);

Now Item2 has the same property data as item1.

现在 Item2 具有与 item1 相同的属性数据。

回答by Azerothian

Because I believe Jon's version is a tad too complicated and and Steve's version is too simple, and I like Daniel's idea of an extension class.

因为我相信 Jon 的版本有点太复杂，而 Steve 的版本太简单了，我喜欢 Daniel 的扩展类的想法。

Plus a Generic version is pretty but unnecessary as all items are objects.

另外，通用版本很漂亮但没有必要，因为所有项目都是对象。

I would like to volunteer my lean and mean version. Credits to all the above. :D

我想自愿提供我的精益和刻薄的版本。归功于以上所有内容。:D

Code:

代码：

using System;
using System.Reflection;
/// <summary>
/// A static class for reflection type functions
/// </summary>
public static class Reflection
{
    /// <summary>
    /// Extension for 'Object' that copies the properties to a destination object.
    /// </summary>
    /// <param name="source">The source.</param>
    /// <param name="destination">The destination.</param>
    public static void CopyProperties(this object source, object destination)
    {
        // If any this null throw an exception
        if (source == null || destination == null)
            throw new Exception("Source or/and Destination Objects are null");
            // Getting the Types of the objects
        Type typeDest = destination.GetType();
        Type typeSrc = source.GetType();

        // Iterate the Properties of the source instance and  
        // populate them from their desination counterparts  
        PropertyInfo[] srcProps = typeSrc.GetProperties();
        foreach (PropertyInfo srcProp in srcProps)
        {
            if (!srcProp.CanRead)
            {
                continue;
            }
            PropertyInfo targetProperty = typeDest.GetProperty(srcProp.Name);
            if (targetProperty == null)
            {
                continue;
            }
            if (!targetProperty.CanWrite)
            {
                continue;
            }
            if (targetProperty.GetSetMethod(true) != null && targetProperty.GetSetMethod(true).IsPrivate)
            {
                continue;
            }
            if ((targetProperty.GetSetMethod().Attributes & MethodAttributes.Static) != 0)
            {
                continue;
            }
            if (!targetProperty.PropertyType.IsAssignableFrom(srcProp.PropertyType))
            {
                continue;
            }
            // Passed all tests, lets set the value
            targetProperty.SetValue(destination, srcProp.GetValue(source, null), null);
        }
    }
}

Usage:

用法：

/// <summary>
/// ExampleCopyObject
/// </summary>
/// <returns></returns>
public object ExampleCopyObject()
{
    object destObject = new object();
    this.CopyProperties(destObject); // inside a class you want to copy from

    Reflection.CopyProperties(this, destObject); // Same as above but directly calling the function

    TestClass srcClass = new TestClass();
    TestStruct destStruct = new TestStruct();
    srcClass.CopyProperties(destStruct); // using the extension directly on a object

    Reflection.CopyProperties(srcClass, destObject); // Same as above but directly calling the function

    //so on and so forth.... your imagination is the limits :D
    return srcClass;
}

public class TestClass
{
    public string Blah { get; set; }
}
public struct TestStruct
{
    public string Blah { get; set; }
}

As I was bored and a linq version was suggested by a comment

因为我很无聊，评论建议了 linq 版本

using System;
using System.Linq;
using System.Reflection;
/// <summary>
/// A static class for reflection type functions
/// </summary>
public static class Reflection
{
    /// <summary>
    /// Extension for 'Object' that copies the properties to a destination object.
    /// </summary>
    /// <param name="source">The source.</param>
    /// <param name="destination">The destination.</param>
    public static void CopyProperties(this object source, object destination)
    {
        // If any this null throw an exception
        if (source == null || destination == null)
            throw new Exception("Source or/and Destination Objects are null");
        // Getting the Types of the objects
        Type typeDest = destination.GetType();
        Type typeSrc = source.GetType();
        // Collect all the valid properties to map
        var results = from srcProp in typeSrc.GetProperties()
                                    let targetProperty = typeDest.GetProperty(srcProp.Name)
                                    where srcProp.CanRead
                                    && targetProperty != null
                                    && (targetProperty.GetSetMethod(true) != null && !targetProperty.GetSetMethod(true).IsPrivate)
                                    && (targetProperty.GetSetMethod().Attributes & MethodAttributes.Static) == 0
                                    && targetProperty.PropertyType.IsAssignableFrom(srcProp.PropertyType)
                                    select new { sourceProperty = srcProp, targetProperty = targetProperty };
        //map the properties
        foreach (var props in results)
        {
            props.targetProperty.SetValue(destination, props.sourceProperty.GetValue(source, null), null);
        }
    }
}

回答by Daniel

Here's a short and sweet version, since you said both of your objects are of the same type:

这是一个简短而甜蜜的版本，因为您说您的两个对象都属于同一类型：

foreach (PropertyInfo property in typeof(YourType).GetProperties().Where(p => p.CanWrite))
{
    property.SetValue(targetObject, property.GetValue(sourceObject, null), null);
}

回答by arteny

Modification of Daniel version to avoid exceptions.

修改 Daniel 版本以避免异常。

foreach (PropertyInfo property in typeof(YourType).GetProperties())
{
  if (property.CanWrite)
  {
    property.SetValue(marketData, property.GetValue(market, null), null);
  }
}

回答by Ashdeep Singh

This short and simple Extension method will allow you to copy matching properties from one object to another with the check of Null value and is writable.

这种简短而简单的扩展方法将允许您通过检查 Null 值并将匹配的属性从一个对象复制到另一个对象并且是可写的。

public static void CopyPropertiesTo(this object fromObject, object toObject)
    {
        PropertyInfo[] toObjectProperties = toObject.GetType().GetProperties();
        foreach (PropertyInfo propTo in toObjectProperties)
        {
            PropertyInfo propFrom = fromObject.GetType().GetProperty(propTo.Name);
            if (propFrom!=null && propFrom.CanWrite)
                propTo.SetValue(toObject, propFrom.GetValue(fromObject, null), null);
        }
    }