如何查找嵌套对象属性的值

Question

I have a function that will find properties with empty values on an object and set them to null. This works fine. The problem now is that sometimes there is a nested object and I'm not sure how to iterate through that to do the same logic.

public static T SetEmptyPropertiesNull<T>(T request, Type type)
{
    foreach (PropertyInfo property in type.GetProperties())
    {
        object value = property.GetValue(request, null);

        if (string.IsNullOrWhiteSpace((value ?? string.Empty).ToString()))
            property.SetValue(request, null);
    }

    return request;
}

So for example, say I have a Customer object and on that object I have an Address object. The function I have now will find all of the empty values on the Customer object and convert them to null, but it also needs to find all of the values on the nested Address object and convert them to null. This function can be called for different object types and not all object types will have a nested object. Any ideas?

UPDATE:

So this works, but I would really like to accomplish this without having to specify the object type, AddressDto. I would like it to be dynamic and accept any object type.

public static T SetEmptyPropertiesNull<T>(T request)
{
    foreach (PropertyInfo property in request.GetType().GetProperties())
    {
        object value = property.GetValue(request, null);

        if (value.GetType() == typeof(AddressDto))
            SetEmptyPropertiesNull(value);
        else if (string.IsNullOrWhiteSpace((value ?? string.Empty).ToString()))
            property.SetValue(request, null);
    }

    return request;
}

Answer 1

First off, assuming the 'type' parameter is the type of the request parameter, you don't need to pass it. typeof(T) will give you the type.

foreach (PropertyInfo property in typeof(T).GetProperties())

Next up, to determine if the property is a class, you can call

value.GetType().IsClass

So your code might look like this:

public static T SetEmptyPropertiesNull<T>(T request)
{
    foreach (PropertyInfo property in typeof(T).GetProperties())
    {
        object value = property.GetValue(request, null);

        if (value.GetType().IsClass)
            SetEmptyPropertiesNull(value);
        else if (string.IsNullOrWhiteSpace((value ?? string.Empty).ToString()))
            property.SetValue(request, null);
    }

    return request;
}

Answer 2

Based on Mark Saphiro answer I changed a litle bit the code to avoid reference cycles. I save the visited objects in a HashSet and only recurse if an object is a class and it's not in the set.

HashSet<object> hashSet = new HashSet<object>();

public static T SetEmptyPropertiesNull<T>(T request)
{
    foreach (PropertyInfo property in typeof(T).GetProperties())
    {
        object value = property.GetValue(request, null);

        if (typeof(value).IsClass && !hashSet.Contains(value))
        {
            hashSet.Add(value);
            SetEmptyPropertiesNull(value);
        }
        else if (string.IsNullOrWhiteSpace((value ?? string.Empty).ToString()))
            property.SetValue(request, null);
     }
     return request;
}