Send JSON string to a C# method

Question

In my ASP.NET page I have the following method:

public static void UpdatePage(string accessCode, string newURL)
{
    HttpContext.Current.Cache[accessCode] = newURL;
}

It actually should receive the accessCode and newURL and update the Cache accordingly. I want to pass the values to that method from JavaScript, using an AJAX request. The code for it is as follows:

function sendUpdate() {
    var code = jsGetQueryString("code"); 
    var url = $("#url_field").val();
    var dataToSend = [ {accessCode: code, newURL: url} ];
    var options = { error: function(msg) { alert(msg.d); },
                        type: "POST", url: "lite_host.aspx/UpdatePage",
                        data: {"items":dataToSend}, 
                        contentType: "application/json; charset=utf-8",
                        dataType: "json",
                        async: false, 
                        success: function(response) { var results = response.d; } }; 
        $.ajax(options);
}

However this doesn't seem to work. Could anybody help me figure out where the bug is?

dmck · Accepted Answer · 2011-10-01 20:34:05Z

1

UpdatePage is a void method that doesn't return anything, so there is nothing to look at in the response.

You could look at the HTTP return code and check that it was 200 OK or you could modify the web method:

public static bool UpdatePage(string accessCode, string newURL)
{
    bool result = true;
    try {
       HttpContext.Current.Cache[accessCode] = newURL;
    }
    catch {
        result = false;
    }

    return result
}

Edit:

It looks like your JSON arguments to the WebMethod are incorrect, you don't need the "items" in your JSON. The arguments should match your webmethod exactly.

function sendUpdate() {
       var code = jsGetQueryString("code"); 
       var url = $("#url_field").val();
       var options = { error: function(msg) { alert(msg.d); },
                       type: "POST", url: "lite_host.aspx/UpdatePage",
                       data: {'accessCode': code, 'newURL': url}, 
                       contentType: "application/json; charset=utf-8",
                       dataType: "json",
                       async: false, 
                       success: function(response) { var results = response.d; } }; 
       $.ajax(options);
}

edited Oct 1, 2011 at 20:34

answered Oct 1, 2011 at 19:02

dmck

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4 Comments

cycero Over a year ago

Thanks for your response. I actually do not want that method to return anything. It just needs to update a value in the cache.

dmck Over a year ago

@cycero I've updated the response, your .ajax options need to be adjusted.

cycero Over a year ago

Thanks for your help. But I'm getting an alert with "undefined" when calling the sendUpdate() function. That's actually the alert called in error case of the AJAX request.

cycero Over a year ago

Thanks @dmck. The problem was actually in the form of the JSON string I was passing to the WebMethod. I had to send it in this form instead: data: "{ accessCode: " + code + ", newURL: '" + url + "' }",

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