jQuery Ajax error handling, show custom exception messages

😎 Showcasing jQuery AJAX Error Handling: How to Display Custom Exception Messages 😱

Are you tired of dealing with cryptic error messages when making AJAX calls using jQuery? 🤷‍♀️ Want to show clear and personalized exception messages to your users instead? 🙌 Look no further! In this blog post, we'll explore a common issue faced by developers: how to show custom exception messages in jQuery AJAX error handling. 🌟

The Problem ❗

Imagine this scenario: you're making an AJAX call to your server using jQuery, and something goes wrong. 😰 Instead of displaying a user-friendly error message, you're greeted with an unhelpful "undefined" exception. 😫 Frustrating, right?

Our fellow dev here asked a similar question on Stack Overflow. 💭 They wanted to display a custom exception message, thrown on the server side using Struts, in their jQuery AJAX error callback. 📢

Here's a snippet of the code they provided:

jQuery("#save").click(function() {
  if (jQuery("#form").jVal()) {
    jQuery.ajax({
      type: "POST",
      url: "saveuser.do",
      dataType: "html",
      data: "userId=" + encodeURIComponent(trim(document.forms[0].userId.value)),
      success: function(response) {
        jQuery("#usergrid").trigger("reloadGrid");
        clear();
        alert("Details saved successfully!!!");
      },
      error: function(xhr, ajaxOptions, thrownError) {
        alert(xhr.status);
        alert(thrownError);
      }
    });
  }
});

In their error callback, when they alerted the thrownError, it returned undefined, while the xhr.status code was 500. 😱 Sounds like a mystery, right? Let's solve it together! 💪

The Solution 💡

The issue here lies in the way the server is handling the exception and how it communicates it back to the client. By default, the error callback's thrownError parameter will only contain the status text of the response.

To display custom exception messages, we need to modify our server-side code to send the exception message as part of the response. Let's dive into some code examples to better understand how to achieve this! 🚀

Server-Side (Struts) Code

On the server side, using Struts as the framework, here's an example of how we can handle exceptions and send custom error messages:

try {
  // Your code logic here
} catch (ApplicationException ex) {
  response.setStatus(500); // Set the response status code to 500 (Internal Server Error)
  response.getWriter().write(ex.getMessage()); // Send the custom exception message as the response body
}

In this example, we catch the ApplicationException (which seems to be a custom exception class) and set the response status code to 500 to indicate an internal server error. We then write the exception message as the response body using response.getWriter().write(ex.getMessage()).

Client-Side (jQuery) Code

Now that the server is properly communicating the exception message, let's modify our jQuery code to display it in our error callback:

error: function(xhr, ajaxOptions, thrownError) {
  alert(xhr.status + ": " + thrownError);
}

By concatenating xhr.status with thrownError, we now get a more informative alert message! 🎉

That's It! ✅

By following these steps, you can now display custom exception messages in your jQuery AJAX error handling. Say goodbye to obscure "undefined" errors and start providing users with personalized messages that actually make sense! 🙌

Got any other jQuery AJAX error handling tips or questions? We'd love to hear from you! 💬 Share your thoughts in the comments below and let's engage in this tech-filled conversation together! 👇

Happy coding! 💻🚀