CODEWITHSUNDEEP
javascriptjqueryasp.netjsonajax
Ageonix
Ageonix

Reputation: 1808

Issue Parsing JSON Response

I'm using AJAX/JQuery to call a WCF service. I have some .NET try/catch error-handling on the service-side that checks to see if the user has timed out, and if they have then I pass back a JSON-converted message which I then parse out on the client-end using parseJSON and use it to re-direct the user back a login page. This is all working great, but I just got a different type of error returned from the service that WASN'T in JSON format (it was XML) so the error-handling function got a javascript error on the client side when it tried to parse the reply. The error was in the jquery.min.js file, and was an 'Invalid character' error.

My question (finally), is there a better way to handle that reply if I can't always rely on it being JSON? In .NET we have a tryParse method available that would work great here, but as far as I know JQuery/Javascript has no such feature. If it can't parse the reply, it throws a JS error.

Here is where the custom JSON exception is thrown:

private HttpSessionState GetUserSession()
{
    HttpSessionState session = HttpContext.Current.Session;

    try
    {
        // This is a method we created that checks if user has timed out and throws the exception if so.
        SessionBuilder.Create(session, HttpContext.Current.Request, HttpContext.Current.Response);
    }
    catch (SessionTimeOutException e)
    {
        throw new WebFaultException<SessionTimeOutException>(new SessionTimeOutException(e.Message), System.Net.HttpStatusCode.BadRequest);
    }

    return session;
}

And here is the client-side code that handles errors in my AJAX request:

error: function (HttpRequest)
{
    // This is the line that gets the exception because the responseText is a standard .NET XML error, not my custom JSON error.
    var parsedReply = $.parseJSON(HttpRequest.responseText);

    if (parsedReply.ClassName === "SessionTimeOutException")
    {
        var url = "../timeout.asp?" + parsedReply.Message;
        window.location.href = url;
    }
}

Upvotes: 0

Views: 120

Answers (1)

J. Titus
J. Titus

Reputation: 9690

JavaScript has try { ... } catch(ex) { ... } also.

error: function (HttpRequest)
{
    var parsedReply;

    try {
        parseReply = $.parseJSON(HttpRequest.responseText);

        if (parsedReply.ClassName === "SessionTimeOutException")
        {
            var url = "../timeout.asp?" + parsedReply.Message;
            window.location.href = url;
        }
    } catch(ex) {
        parsedReply = HttpRequest.responseText;

        //Do something else
    }
}

Upvotes: 1

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