Passing Data from a requestet CakePHP-Function back to jQuery - ajax

Question

I'm trying to build up Ajax-Validations by using the jQuery-Event .blur()
I've set the field names to the id of the input-fields to identify them and giving the required data for validation by an ajax-request to the Controller. So far, so good, I could start with the validation, but here's the question:
If there's an error - How do I send the Errormessage back to jQuery, so that I can do another ajax-request to give it out?
Thanks to all help, that'll hopefully come.
Here's the JQuery-Script so far:
$('.registration').blur(function(){
var id = $(this).attr('id');
var value = $(this).val();
var dataString = 'id=' + id +'&value=' + value;
$.ajax({
type: "POST",
url: "users/validate",
data: dataString,
cache: false,
success: function(){ }
});
});

Answer 1

I would recommend using Cake's RequestHandler component to detect the ajax request. Then you'll set the layout to false so that only the view is returned.
Then perform your validation as normal with your preferred method.
Finally, if the validation fails, you can return a 'json' view in which you render the returned validation errors.
Here's a basic example covering just the ajax request and the failed validation:
Users controller:
/**
* use the RequestHandler component
*/
public $components = array('RequestHandler');
/**
* validate action
*/
public function validate()
{
/**
* check if it's an ajax request
*/
if ($this->RequestHandler->isAjax()) {
$this->layout = false;
/**
* set incoming data in the user models data property
*/
$this->User->set($this->data);
if (!$this->User->validates()) {
/**
* return the validation errors and use a view than renders the json
*/
$this->set('errors', $this->User->invalidFields());
$this->render('/users/json/validate');
}
}
}
users/json/validate.ctp
<?php echo $javascript->object($errors); ?>

Answer 2

The page that validates it should print a JSON with the results; something like this
View:
<?php
echo $javascript->object($result);
?>
or
<?php
echo json_encode($result);
?>
Controller
assuming you do you your validations and have $validate variable that is true if evcrything is ok
$this->layout='json_cont';
//do your validations here
if ($validate)
$result = array(
'result' => 1,
'error' => null
);
else
$result = array(
'result' => 0,
'error' => 'error validating'
);
$this->set('result', '$result);
You also need the layout json_cont
<?php
header("Pragma: no-cache");
header("Cache-Control: no-store, no-cache, max-age=0, must-revalidate");
header('Content-Type: text/x-json');
echo $content_for_layout;
?>
finally you just need to change your ajax function just a little like this
$.ajax({
type: "POST",
url: "users/validate",
data: dataString,
cache: false,
dataType: "json",
dataFilter: function(data, type) {
return data;
},
success: function(data) {
if (data != null && data.result == 0) {
alert(data.error);
}
else {
//do here something that accepts your validation, like a js function to give some info to the user or something
}
},
error: function(data) {
try {
alert('error doing the validation');
} catch (e) { }
}
});
i think im not missing anything, hope this helps you :D