NovoGeek's Blog (Archive)

In my previous post, I have explained how to pass complex types using jQuery and JayRock in .NET 2.0 framework. I was digging a bit into Dave’s example (using complex types to make calling services less complex) in .NET 3.5 framework, to find how easier JSON serilaization/deserialization can be made.

When a Web service class is decorated with “ScriptService” attribute, which is in the System.Web.Script.Services namespace in .NET 3.5, the web service returns data in JSON format [MSDN]. Whether the returned value is a string or an object, it will be in JSON format. So no need of writing chunks of code for serializing objects explicitly.

Therefore, all that we need to do is to simply decorate our web service class with “ScriptService” attribute and  return an object from the server. So, to create a JSON object like this:

{"d":{"FirstName":"Krishna","LastName":"Chaitanya","City":"Hyd","State"
:"Andhra","Country":"India"}}

We can simply return a person object like this:

<WebMethod()> _

    Public Function fnFetchDetailsClass() As Person

        Dim objPerson As New Person

        Try

            objPerson.FirstName = "Krishna"

            objPerson.LastName = "Chaitanya"

            objPerson.City = "Hyd"

            objPerson.State = "Andhra"

            objPerson.Country = "India"

        Catch ex As Exception

        End Try

        Return objPerson

    End Function

In some situations (like in client side templating), we might need to create custom, complex JSON objects on the fly. In such situations, we can make use of .NET’s “ListDictionary” and “ArrayList” classes.

The above example can be re-written using ListDictionary as:

<WebMethod()> _

Public Function fnFetchDetails() As ListDictionary

    Dim jsonObj As New ListDictionary

    Try

        jsonObj.Item("fname") = "Krishna"

        jsonObj.Item("lname") = "Chaitanya"

        jsonObj.Item("city") = "Hyd"

        jsonObj.Item("state") = "Andhra"

        jsonObj.Item("country") = "India"

        Return jsonObj

    Catch ex As Exception

        jsonObj.Item("Error") = "Error at server"

        Return jsonObj

    End Try

End Function

Thus, using JSON is made easier in .NET 3.5.

Here is a simple demo which makes things clear. (I have used jQuery for making AJAX calls.)

(Note: ListDictionary stores values in Name/Value pairs, which is useful in building JSON Object. Similarly, an ArrayList can be used to build JSON Arrays. Therefore, these two can be used instead of JsonObject and JsonArray classes of Jayrock in my post Converting ASP.NET DataTable to JSON using JayRock.)