Wordpress custom submit button

Question

I'm getting a little lost :d

Short explanation:

I want to be able to process $_POST data when a submit button is clicked on a custom post type. So firstly how or what function can I use to add a custom input submit, and secondly how can I build a function for the submitting of this button? Can't seem to find a solution anywhere!

Long explanation:

I'm building a authorisation paypal system for a custom post type named orders. I have my orders in a table which I access using a class. I have my payment information and I know what I have to do which is capture the payment, but I want a button to be able to do this and return errors. So I want a separate button to 'update' and a method of capturing the action so I can do my API call etc.

I don't want a plugin. I just need to know how to make an input and then use $_POST.

Can I do it with a custom meta box?

add_meta_box('order_payment','build_order_payment_info','orders','side');

function build_order_payment_info($post){
    <input name="ID" type="hidden" value="ID of my payment">
    <input name="Other info needed" type="hidden" value="">
    <input name="submitPayment" type="submit" value="Process payment">
}

Then in my order meta

add_action('save_post','save_order');
function save_order(){
    global$post;
    if(isset($_POST['submitPayment'])&&!empty($_POST['ID'])){
        //send payment api
    }else echo"There was an error with the payment";
}

Would something like that work? I've also read that I can provide the custom post type to the add_action function like this: 'save_post_orders', is that correct?

Answer 1

Using admin_post action and wp_nonce_field.

When using admin_post it will require a hidden input within the form.

<input name='action' type="hidden" value="add_new_client">

When using this you want to add your action too

add_action('admin_post_add_new_client',array('clients','add_new_client'));

This will result in the form being 'submitted' to clients::add_new_client()

public static function add_new_client(){
   //access $post info here but first do some admin checks etc
   if(!current_user_can('manage_options'))wp_die('you are not allowed to managed these settings');
    check_admin_referer('newClient');
    //do your validation and add whatever 
}

I've also used wp_nonce_feild within my form like this

public function buildForm(){
    echo"<form name='newclientsForm' action='".admin_url('admin.php?page=clients')."'><table class='form-table'>";
    wp_nonce_field('newClient');
    //do rest of form
}

Answer 2

If I understand you right, you want some input fields and a button that sends the values from the inputs to a file on the server and that file should do something with it?
Well if thats the case, you can do that on 2 ways:
1 - the good old submit button
2 - bind an ajax call to an element
examples:
1: http://www.w3schools.com/tags/att_button_form.asp
2: http://api.jquery.com/jquery.ajax/

well the rest is then just a script on server side (http://php.net/manual/en/reserved.variables.post.php)
note to 2: at the bottom are some examples, they are easier to understand if you've never done this before