Question

I am a little confused about when do I have to serialize objects using JSON serialization and when it is not necessary (even needless).

I’ve spent several days trying to send a list of simple objects using jQuery.ajax and JSON.
I have a class named Product:

public class Product
{
    public string Name;
    public string Qnt;
    public string Price;
}

and a web method that returns a list filled with Products

List<Product> p = new List<Product>();

I used System.Web.Script.Serialization.JavaScriptSerializer to serialize this list in JSON and send it to the client as a string, where i format it using jQuery

$.each(msg.d, function (index, Product) {
    $('#details').append('<p>Name: ' + Product.Name 
                           + '<br />Quantity: ' + Product.Qnt 
                           + '<br />Price: ' + Product.Price + '</p>');
});

…and it wouldn’t work… Because at the client side, I just get a long string (it would be parsed character by character, when I use $.each) – I learned that it should be parsed first

It took time until I realised that I just have to return it as a List of Product objects, without serialization, and client gets list of products in perfect JSON format!

EDIT:
What I actually don’t understand: if I serialize my list, it returns JSON formated string that have to be parsed before I can use it. If i don’t serialize my list, it returns the same data, but as an object, not a string, so I can use it right away. How can I know do I have to use JSON serialization on my data, or it will always be done by framework?

Answer 1

You’re not returning your List<Product> directly to the client. It’s not going over the wire as a List<Product> – there’s no such concept at the HTTP level. However, the server-side framework you’re using is performing the JSON serialization for you. If you perform serialization first, then the serialized string will then be JSON-serialized, including another level of escaping etc.