Difficulty displaying error message using AJAX jQuery API and PHP. - php

Question

I'm using the jQuery AJAX function in order to retrieve data from my mySQL database without having to refresh the page. I have everything in working order, my query's are retrieving the correct data from my database. However, I am struggling to echo out an error message when no data can be retrieved based on the users input. I have a php file that provides the user interface for the user to search from, it also contains the following Scripts in the document head. Here is what I have so far:-
<script type="text/javascript">
$(function(){
$('#users').keyup(function(){
var inpvalue= $('#users').val();
});
});
</script>
<script type="text/javascript">
$(function(){
$('#users').keyup(function(){
var inpval=$('#users').val();
$.ajax({
type: 'POST',
data: ({p : inpval}),
url: 'data.php',
success: function(data) {
$('#output_div').html(data);
}
});
});
});
</script>
Any help would be greatly appreciated, sorry if I haven't explained myself very well.
Thankyou.

Answer 1

Modify your .ajax() call so you can detect error conditions:
$.ajax({
type: 'POST',
data: ({p : inpval}),
url: 'data.php',
success: function(data) {
$('#output_div').html(data);
},
error: function (jqXHR, textStatus, errorThrown) {
console.log(errorThrown);
}
});
This is just to get you started: see http://api.jquery.com/jQuery.ajax/ for more details on what you can do with the error handler.
Of course, it's possible that you're getting a good HTTP status from the call, but this defensive programming will make sure.
A tool like Firebug running in your browser can also help you detect bad HTTP status code returns.

Answer 2

In data.php you have to output the error when the data is invalid.

Answer 3

The error setting for $.ajax will only get called if the actual ajax request has a problem like if the server returns a 404. You would have to return an error in your json and check for it like this:
$('#users').keyup(function(){
var inpval=$('#users').val();
$.ajax({
type: 'POST',
data: ({p : inpval}),
url: 'data.php',
success: function(data) {
if(!data.error) {
$('#output_div').html(data);
}
else {
// show error
}
}
});
});
And then you would return your normal json when the data is fine and then something like this for the error:
{"error": "Oh NOES!"}