Using Form Validation submitHandler to send 2 AJAX requests? - ajax

Question

I've got a pretty strong understanding of php, html & css but i've only just started to dive into javascript & jQuery.
The problem i'm facing is that I have a form on a page that I want first to validate, then when it passes validation to submit 2 ajax requests; the first to insert data into a table in my database and the second to run a query on another table and return the result.
I've got the latter working just fine using the submitHandler method to send the ajax request and update a div on my page with it's result. When I added a second ajax call after or before this one it seems to break...
My question is should there be a problem with having 2 ajax calls in the submitHandler, like below, and if so what would be the correct way to go about this, or even a better way?
$("#contactform").validate({
rules: ...
submitHandler: function() {
// First to insert the contact details using input#firstname etc.
var firstname = $("#firstname").value();
var lastname = $("#lastname").value();
var contactString = 'firstname='+ firstname + '&lastname=' + lastname;
$.ajax({
type: "POST",
url: "insertcontact.php",
data: quoteString,
success: function(server_response){
$('#yourquote').html(server_response).show();
}
});
// Second use width & height submitted from previous page for processquote.php
var width = <?php echo json_encode($cleanpost['width']); ?>;
var height = <?php echo json_encode($cleanpost['height']); ?>;
var quoteString = 'width='+ width + '&height=' + height;
$.ajax({
type: "POST",
url: "processquote.php",
data: quoteString,
success: function(server_response){
$('#yourquote').html(server_response).show();
}
});
}
});
I'm using the 'jquery.validate.js' validation plugin. Again my goal is such that once someone has entered valid details on my form, using Ajax their contact data is inserted into the database then the database is queried using fields submitted on the previous page to retrieve a numerical result to display on the page, without a refresh.
Any pointers you could give me would be much appreciated!
Rob
EDIT: Learning Javascript & Jquery simultaneously isn't such a good idea it seems, i've confused: this.value = ''; with $(this).val(''); as shown in the first 2 variable declarations, this is what was causing problems! Thanks for your useful help anyway guys, will upboat for your assistance.

Answer 1

In your first .ajax() call, you are trying to pass it a value in the data: parameter that you have not created yet. I believe you are wanting to send it the contactString instead.
Unless your two queries depend on each other being done sequentially then you should be able to execute them both asynchronously (essentially at the same moment). If you want the second AJAX call to happen after the first one, you could always pass all of your data parameters to insertcontact.php and once the insertion is done, execute processquote.php with the values you already passed through.
Lastly, I wonder if you are meaning to do this, but both of your AJAX calls overwrite whatever is in the #yourquote DOM element and show it. You might want to provide a separate element to put the response in for each of your two requests. Perhaps #yourquoteinserted and #yourquoteprocessed?
Edit: BigRob, from your comment it sounds as if you want to make synchronous AJAX queries, check out the async property of your .ajax() call. This is from the .ajax() documentation:
async Boolean
Default: true
By default, all requests are sent asynchronously (i.e. this is set to true by default). If you need synchronous requests, set this option to false. Cross-domain requests and dataType: "jsonp" requests do not support synchronous operation. Note that synchronous requests may temporarily lock the browser, disabling any actions while the request is active.
(emphasis mine)
However, I could be wrong about this but you might actually be able to call one asynchronous AJAX method from within the success function of another. If it starts looking too intermingled for you, you might want to extract the inner call into a function. Rough approximation of what it might look like:
$.ajax({url, data:contactString,
success: function(server_response) {
extractedId = server_response; // you can return data many ways
$.ajax({url2, data:quoteString+"&extra="+extractedId,...
});
}
});
If you perform a synchronous call by setting async:false in the first AJAX call, then you could just store the result into an external (to the AJAX call) variable (or if that doesn't work store it in some DOM element temporarily). Then the javascript will pause execution and won't fire your second AJAX call until the first one has returned.
This is all hypothetical for now, though, and just based off of my understanding of how it should work.