error handling during ajax file upload using jquery form plugin - php

Question

i have a situation where i'm stuck at the idea of catching the appropriate error during file upload in the ajax response in jquery form-plugin.
i'l give an idea of what i want to achieve through some pseudocode.
My php is :
$file = strtolower($_FILES["myfile"]["name"]);
$extension = substr($file, strrpos($file, '.') + 1);
if($extension == 'jpg'){
// upload the file
if(move_uploaded_file($_FILES["myfile"]["tmp_name"], $folder . $finalFilename)){
// do something here like
echo "<div id='statusContainer'>
<table><tr><td>
<img src='uploads/".$finalFilename."'>
</td></tr>
<tr><td>".$finalts."</td></tr></table>
</div>";
}
} else {
$error = 1; // will give numbers to different errors like filetype error, size error etc..
}
now my JS code is :
(function() {
var status = $('#status');
$('form').ajaxForm({
complete: function(xhr) {
if(xhr.responseText == "// what do i get echoed here so i can run an array and show user appropriate error like size error, type error etc. // "){
// i want to open a dialog box with correct error message//
} else{
status.hide().html(xhr.responseText).fadeIn(1000);
}
}
});
})();
shall i get the error number echoed in the ajax response and run through an array to get the message? but then i'll have to put in a lot of if conditions in the ajax response with different error numbers.
Please anyone have a more logical idea??

Answer 1

you could make an array and pass error json_encode()'ing it and parse json response from ajaxForm, like
php part:
$responseArr = array();
if( file_is_uploaded ) {
$responseArr["error"] = "0";
$responseArr["message"] = "File uploaded success message";
}
else {
$responseArr["error"] = "1";
$responseArr["message"] = "Error message here";
}
echo json_encode($responseArr); //pass it as response
js part::
$('form').ajaxForm({
dataType: "json",
success: function(response) {
//parse json response and perform accordingly
console.log( response );
}
});

Answer 2

To cut down on traversing an array in JS, and matching error IDs to descriptions, could you associate the error description itself to be relayed in the ajax response? This would keep your JS lean and keep error handling serverside.
Example:
<tr><td>".$finalts."</td></tr></table>
</div>";
}
$error_descriptions = array("Filesize Error", "Extension Error");
} else {
$error = error_descriptions[1];
}