Remove the null property from object

Question

,I have one class in which I have three properties now what I want to do, if in the object if any one of null or empty then I want to remove it from the object below is my code.

public class TestClass
{
    public string Name { get; set; }
    public int ID { get; set; }
    public DateTime? DateTime { get; set; }
    public string Address { get; set; }
}
       TestClass t=new TestClass();
        t.Address="address";
        t.ID=132;
        t.Name=string.Empty;
        t.DateTime=null;

Now here I want the object of TestClass but in that Name and DateTime property should not be their in the object, is it possible? Please help me

Answer 1

I was bored and got this in LINQPad

void Main()
{
    TestClass t=new TestClass();
    t.Address="address";
    t.ID=132;
    t.Name=string.Empty;
    t.DateTime=null;

    t.Dump();
    var ret = t.FixMeUp();
    ((object)ret).Dump();
}

public static class ReClasser
{
    public static dynamic FixMeUp<T>(this T fixMe)
    {
        var t = fixMe.GetType();
        var returnClass = new ExpandoObject() as IDictionary<string, object>;
        foreach(var pr in t.GetProperties())
        {
            var val = pr.GetValue(fixMe);
            if(val is string && string.IsNullOrWhiteSpace(val.ToString()))
            {
            }
            else if(val == null)
            {
            }
            else
            {
                returnClass.Add(pr.Name, val);
            }
        }
        return returnClass;
    }
}

public class TestClass
{
    public string Name { get; set; }
    public int ID { get; set; }
    public DateTime? DateTime { get; set; }
    public string Address { get; set; }
}

Answer 2

There's no such concept as removing a property from an individual object. The type decided which properties are present - not individual objects.

In particular, it will always be valid to have a method like this:

public void ShowDateTime(TestClass t)
{
    Console.WriteLine(t.DateTme);
}

That code has no way of knowing whether you've wanted to "remove" the DateTime property from the object that t refers to. If the value is null, it will just get that value - that's fine. But you can't remove the property itself.

If you're listing the properties of an object somewhere, you should do the filtering there, instead.

EDIT: Okay, no you've given us some context:

ok I am using Schemaless database so null and empty value also store space in database that's the reason

So in the code you're using which populates that database, just don't set any fields which corresponds to properties with a null value. That's purely a database population concern - not a matter for the object itself.

(I'd also argue that you should consider how much space you'll really save by doing this. Do you really care that much?)

Answer 3

Hereby a 'slightly' more clear and shorter version of the accepted answer.

        /// <returns>A dynamic object with only the filled properties of an object</returns>
        public static object ConvertToObjectWithoutPropertiesWithNullValues<T>(this T objectToTransform)
        {
            var type = objectToTransform.GetType();
            var returnClass = new ExpandoObject() as IDictionary<string, object>;
            foreach (var propertyInfo in type.GetProperties())
            {
                var value = propertyInfo.GetValue(objectToTransform);
                var valueIsNotAString = !(value is string && !string.IsNullOrWhiteSpace(value.ToString()));
                if (valueIsNotAString && value != null)
                {
                    returnClass.Add(propertyInfo.Name, value);
                }
            }
            return returnClass;
        }

Answer 4

You could take advantage of the dynamic type:

class Program
{
    static void Main(string[] args)
    {
        List<dynamic> list = new List<dynamic>();
        dynamic
            t1 = new ExpandoObject(),
            t2 = new ExpandoObject();

        t1.Address = "address1";
        t1.ID = 132;

        t2.Address = "address2";
        t2.ID = 133;
        t2.Name = "someName";
        t2.DateTime = DateTime.Now;

        list.AddRange(new[] { t1, t2 });

        // later in your code
        list.Select((obj, index) =>
            new { index, obj }).ToList().ForEach(item =>
        {
            Console.WriteLine("Object #{0}", item.index);
            ((IDictionary<string, object>)item.obj).ToList()
                .ForEach(i =>
                {
                    Console.WriteLine("Property: {0} Value: {1}",
                        i.Key, i.Value);
                });
            Console.WriteLine();
        });

        // or maybe generate JSON
        var s = JsonSerializer.Create();
        var sb=new StringBuilder();
        var w=new StringWriter(sb);
        var items = list.Select(item =>
        {
            sb.Clear();
            s.Serialize(w, item);
            return sb.ToString();
        });

        items.ToList().ForEach(json =>
        {
            Console.WriteLine(json);
        });
    }
}

Answer 5

May be interfaces will be handy:

public interface IAdressAndId
    {
        int ID { get; set; }
        string Address { get; set; }
    }
    public interface INameAndDate
    {
        string Name { get; set; }
        DateTime? DateTime { get; set; }
    }
    public class TestClass : IAdressAndId, INameAndDate
{
    public string Name { get; set; }
    public int ID { get; set; }
    public DateTime? DateTime { get; set; }
    public string Address { get; set; }
}

Creating object:

IAdressAndId t = new TestClass()
            {
                Address = "address",
                ID = 132,
                Name = string.Empty,
                DateTime = null
            };

Also u can put your interfaces in separate namespace and make your class declaration as internal. After that create some public factories which will create the instances of your classes.