C# Reflection - merge two objects together

Question

I have a need to update object A\'s property if null with that from object B\'s equivalent property if that is not null. I wanted code I can use for various objects.

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Answer 1

Hi I modified Ben Robinsons solution in order to not overwrite Collections or list, instead, it adds the elements of one object to the other one where the merging is happening:

 public static class ExtensionMethods
{
    public static TEntity CopyTo(this TEntity OriginalEntity, TEntity EntityToMergeOn)
    {
        PropertyInfo[] oProperties = OriginalEntity.GetType().GetProperties();

        foreach (PropertyInfo CurrentProperty in oProperties.Where(p => p.CanWrite))
        {
            var originalValue = CurrentProperty.GetValue(EntityToMergeOn);

            if (originalValue != null)
            {
                IListLogic(OriginalEntity, CurrentProperty, originalValue);
            }
            else
            {
                var value = CurrentProperty.GetValue(OriginalEntity, null);
                CurrentProperty.SetValue(EntityToMergeOn, value, null);
            }
        }

        return OriginalEntity;
    }

    private static void IListLogic(TEntity OriginalEntity, PropertyInfo CurrentProperty, object originalValue)
    {
        if (originalValue is IList)
        {
            var tempList = (originalValue as IList);
            var existingList = CurrentProperty.GetValue(OriginalEntity) as IList;

            foreach (var item in tempList)
            {
                existingList.Add(item);
            }

        }
    }
}