How to access JavaScript objects in code behind (C#/ASP.NET)

Question

Hi,

I am using the web kit browsers local database to temporarily store some data and when I want to access it I create an object

function patientSelectHandler(transaction, results) {
        var row = results.rows.item(0);
        var patient = new Object();

        patient.name = row['name']
        patient.dob = row['dob']
        patient.gender = row['gender']
}

Is there a way to access this object from code behind, without having to populate textfields/labels/dropdowns and then get the values from there?

example as it is now:

function patientSelectHandler(transaction, results) {
        var row = results.rows.item(0);
        var patient = new Object();

        patient.name = row['name']
        patient.dob = row['dob']
        patient.gender = row['gender']


        $('#txtPatientName').val(patient.name);
        $('#txtDOB').val(patient.dob);
    $('#ddlGender').val(patient.gender);
}

edit:

Updating my example a bit:

    var patientString = JSON.stringify(patient);
    var inputField = $("<input type='text' name='hiddenField" + i + "' id='hiddenField" + i + "'></input>");
    $('#Patients').append(inputField);
    $('#hiddenField' + i).val(patientString);

and then a loop in the code behind

            for (int i = 0; i <= count; i++)
            {
                string n = String.Format("{0}", Request.Form["hiddenField" + i]).ToString();
                JObject o = JObject.Parse(n);
                string name = (string)o["name"];
//now I can get all values into variables and use them when calling the web service
}

Answer 1

If you have many fields to send, you can JSON encode everything and put it into a single multiline text field (textarea). Then you can easily decode it on the server.

Answer 2

You don't need to set it to textfields for any reason...

I would probably do something like

var patientString = JSON.stringify(patient);
$('#myHiddenInput').val(patientString);

Otherwise, depending on the flow of your application, you can post that object in string form to the server using AJAX.

Then, you will have to use a method to parse that string back into object formation. I'm not to familiar with c# but i'm sure it would be easy to find or write such a method.

Answer 3

Keep in mind -

1. When your server code runs, it builds up a page object that it then uses to generate html to send to the browser. Once the html is generated that page object is destroyed. By the time the browser shows your page, your server resources don't exist any more.
2. When the browser submits a request for a page, it destroys the DOM for whatever page it's showing. So by the time your server starts, your javascript doesn't exist any more.

Thus, the two systems are normally completely separate. You can get around this by passing ajax json messages between client and server.

Answer 4

I would use AJAX post to store your JSON object on the server.

var str = JSON.stringify(...);

$.ajax({

    type: "POST",

    contentType: "application/json; charset=utf-8",

    url: "Default.aspx/validate",

    data: str,

    error: function(XMLHttpRequest, textStatus, errorThrown) {

        ...
    },

    success: ajaxCallback,

    dataType: "json"

});

And on the server

[WebMethod]
public static string validate(Dictionary<string, object> patient)
{
    ...
    //return your JSON response
}

And then just iterate through Dictionary object on the server (key - object parameter, value - it's value).