使用C＃中的反射添加到未知类型的集合

Question

So I am using reflection to loop through the properties of one object and populating the values on a different object with properties of the same name. This works great but the problem comes when the property type is a collection. I want to be able to loop through each of the objects in the source collection and populate the same list with objects in the source collection.

public class SourceMessage
{
    public string Name { get; set; }
    public int Version { get; set; }
    public IList<ValueDefinition> Values { get; set; }
}

public class ValueDefinition
{
    public string Name { get; set; }
    public string Value { get; set; }
}

public class TargetObject
{
    public TargetObject()
    {
        Values = new List<TargetValueDefinition>();
    }
    public string Name { get; set; }
    public int Version { get; set; }
    public IList<TargetValueDefinition> Values { get; set; }
}

public class TargetValueDefinition
{
    public string Name { get; set; }
    public string Value { get; set; }
}

Then I use Reflection to populate the target from the source.

public static void PopulateFromMessage<T, TS>(ref T targetEntity, TS message)
{
    var sourceType = typeof(TS);
    var targetType = typeof(T);

    foreach (var targetPropInfo in targetType.GetProperties())
    {
        if (sourceType.GetProperty(targetPropInfo.Name) != null)
        {
            var obj = sourceType.GetProperty(targetPropInfo.Name);
            if (obj.PropertyType.Namespace == "System.Collections.Generic")
            {
                //var x = targetType.GetProperty(targetPropInfo.Name);
                //PopulateFromMessage(ref x, sourceType.GetProperty(targetPropInfo.Name));
                continue;
            }
            targetPropInfo.SetValue(targetEntity, sourceType.GetProperty(targetPropInfo.Name).GetValue(message), null);
        }
    }
}

So calling this would be like this:

private void DenormalizeMessage(SourceMessage message)
{
    var newTargetObject = new TargetObject();
    PopulateFromMessage(ref newTargetObject , message);
}

I can identify when the property is a collection but am uncertain of how to create new TargetValueDefinitions and populate them with the values from ValueDefinitions. In the end it is pretty much a copy of the SourceMessage in the form of a TargetObject.

This all stems from receiving messages and transforming them into objects with the same property names.

Answer 1

You should create a interface for each class (implement the methods and properties on interface) and implement it in each class. After, in function PopulateFromMessage should specify the interface allowed in method, with this you can use directly the properties of class with T and TS generic types.

Answer 2

Disclaimer: This is extremely unsafe to do and makes a lot of assumptions but it should puth you on the right path.

Change you method to this:

public static void PopulateFromMessage<T, TS>(T targetEntity, TS message)
    {
        var sourceType = typeof (TS);
        var targetType = typeof (T);

        foreach (var targetPropInfo in targetType.GetProperties())
        {
            if (targetPropInfo.PropertyType.IsGenericType)
            {
                if (targetPropInfo.PropertyType.GetGenericTypeDefinition() == typeof(IList<>))
                {
                    var originalList = sourceType.GetProperty(targetPropInfo.Name).GetValue(message) as IList;

                    if (originalList != null)
                    {
                        var argumentType = targetPropInfo.PropertyType.GetGenericArguments();
                        var listType = typeof (List<>);
                        var concreteType = listType.MakeGenericType(argumentType);
                        var newList = Activator.CreateInstance(concreteType) as IList;

                        foreach (var original in originalList)
                        {
                            var targetValue = Activator.CreateInstance(argumentType[0]);

                            // do this yourself. Here we're converting ValueDefinition to TargetValueDefinition
                            // targetValue.Fill(original);
                        }

                        targetPropInfo.SetValue(targetEntity, newList);
                    }
                }
            }
            else
            {
                if (sourceType.GetProperty(targetPropInfo.Name) != null)
                {
                    var obj = sourceType.GetProperty(targetPropInfo.Name);
                    if (obj.PropertyType.Namespace == "System.Collections.Generic")
                    {
                        //var x = targetType.GetProperty(targetPropInfo.Name);
                        //PopulateFromMessage(ref x, sourceType.GetProperty(targetPropInfo.Name));
                        continue;
                    }
                    targetPropInfo.SetValue(targetEntity, sourceType.GetProperty(targetPropInfo.Name).GetValue(message), null);
                }
            }
        }
    }

Answer 3

If your problem is iterating through items contained inside a single property when it is a collection, then the key would be to read the property value into a dynamic variable and not an object variable that is by default, this way you could use a foreach for it.

dynamic propVal = inputProperty.GetValue(item);
foreach (var subItem in propVal)
{    
//do your stuff
}