Filtering Properties from Dto before outputting as Json

Question

I have a REST API for exposing quote data. Sometimes API can take specific parameters to provide data for.

General usage: http://blah.com/quotes?symbol=MSFT

specific usage: http://blah.com/quotes?symbol=MSFT&params=[Symbol,Sector,Industry]

DTO:

public class QuoteDto 
{
    public string CompanyName { get; private set; }
    public string Symbol { get; private set; }
    public string Exchange { get; private set; }
    public string Sector { get; private set; }
    public string Industry { get; private set; }
    . . . 
}

during general usage i simply serialize my DTO into Json. But when i get specific request how can i filter out unwanted params from my dto before i serialize ??

is there any third party lib to do this? I can use reflection but thats way to wonky. I am using ASP.NET MVC and C#

Answer 1

Use a mix of two techniques - the first is to write your own json result.

Control serializer in JsonResult aka Json function in ASP.Net MVC?

http://brianreiter.org/2011/01/03/custom-jsonresult-class-for-asp-net-mvc-to-avoid-maxjsonlength-exceeded-exception/

Secondly, instead of using for ex. javascriptserializer, you would in turn use JSON.Net to manually do the serialization. This way you could exclude whatever properties you want based on your rules. A block of code from their site shows its quite simple to serialize http://james.newtonking.com/projects/json/help/ReadingWritingJSON.html

StringBuilder sb = new StringBuilder();
StringWriter sw = new StringWriter(sb);

using (JsonWriter jsonWriter = new JsonTextWriter(sw))
{
  jsonWriter.Formatting = Formatting.Indented;
  jsonWriter.WriteStartObject();
  jsonWriter.WritePropertyName("CPU");
  jsonWriter.WriteValue("Intel");

  jsonWriter.WritePropertyName("PSU");
  jsonWriter.WriteValue("500W");

  jsonWriter.WritePropertyName("Drives");
  jsonWriter.WriteStartArray();

  jsonWriter.WriteValue("DVD read/writer");
  jsonWriter.WriteComment("(broken)");

  jsonWriter.WriteValue("500 gigabyte hard drive");
  jsonWriter.WriteValue("200 gigabype hard drive");

  jsonWriter.WriteEnd();

  jsonWriter.WriteEndObject();

}

Answer 2

I use NHibernate quite a bit, but it's more than I need to send down everything in the JSON.

While hacky, I like to use a Dictionary<string, object> and then just add the members I want to send down.

return Json(someDict);