Custom JavaScriptConverter for DateTime?

Question

I have an object, it has a DateTime property... I want to pass that object from an .ashx handler back to a webpage via AJAX/JSON... I don\'t want to use 3rd party controls..

Answer 1

JavaScriptSerializer can definitely do what you desire.

It's possible to customize the serialization performed by JavaScriptSerializer for any type by creating a custom converter and registering it with the serializer. If you have a class called Person, we could create a converter like so:

public class Person
{
    public string Name { get; set; }
    public DateTime Birthday { get; set; }
}

public class PersonConverter : JavaScriptConverter
{
    private const string _dateFormat = "MM/dd/yyyy";

    public override IEnumerable SupportedTypes
    {
        get
        {
            return new[] { typeof(Person) };
        }
    }

    public override object Deserialize(IDictionary dictionary, Type type, JavaScriptSerializer serializer)
    {
        Person p = new Person();
        foreach (string key in dictionary.Keys)
        {
            switch (key)
            {
                case "Name":
                    p.Name = (string)dictionary[key];
                    break;

                case "Birthday":
                    p.Birthday = DateTime.ParseExact(dictionary[key] as string, _dateFormat, DateTimeFormatInfo.InvariantInfo);
                    break;
            }
        }
        return p;
    }

    public override IDictionary Serialize(object obj, JavaScriptSerializer serializer)
    {
        Person p = (Person)obj;
        IDictionary serialized = new Dictionary();
        serialized["Name"] = p.Name;
        serialized["Birthday"] = p.Birthday.ToString(_dateFormat);
        return serialized;
    }
}

And use it like this:

JavaScriptSerializer serializer = new JavaScriptSerializer();
serializer.RegisterConverters(new[] { new PersonConverter() });

Person p = new Person
            {
                Name = "User Name",
                Birthday = DateTime.Now
            };

string json = serializer.Serialize(p);
Console.WriteLine(json);
// {"Name":"User Name","Birthday":"12/20/2010"}

Person fromJson = serializer.Deserialize(json);
Console.WriteLine(String.Format("{0}, {1}", fromJson.Name, fromJson.Birthday)); 
// User Name, 12/20/2010 12:00:00 AM