Add member tag on profile form submit

I had a quick look at the API section but not sure I have the time to get my head around making an app. Would it not work to simply point the redirect for the form to a PHP page which includes the add_tag line and then redirects back to the original page?

I've attempted this but for some reason it won't recognise the isset name_change (works ok if I remove that).

profile.html

<perch:form id="profile" class="" method="post" app="perch_members" next="/account/update-name.php">

    <div class="mb-30">
        <perch:label for="first_name">First name</perch:label>
        <perch:input type="text" id="first_name" class="input" required="true" label="First name" />
        <perch:error for="first_name" type="required"><p class="alert alert--fail">Please add your first name</p></perch:error>
    </div>

    <div class="mb-30">
        <perch:label for="last_name">Last name</perch:label>
        <perch:input type="text" id="last_name" class="input" required="true" label="Last name" />
        <perch:error for="last_name" type="required"><p class="alert alert--fail">Please add your surname</p></perch:error>
    </div>

    <div>
        <perch:input type="hidden" id="name_change" value="true" />
        <perch:input type="submit" class="button button--success" value="Update name" />
        <perch:input type="hidden" id="token" />
    </div>

    <perch:success>
        <div class="alert"><p>Your details have been updated. <a href="/dashboard">Back to Dashboard</a></p></div>
    </perch:success>

</perch:form>

update-name.php

<?php
include('../perch/runtime.php');

if (isset($_POST['name_change']) && perch_member_logged_in()) {

    perch_member_add_tag('name-changed');

    PerchSystem::redirect('index.php?change=success');

}

else {
    PerchSystem::redirect('index.php?change=fail');
}

?>

Ah. So how can I check the form was submitted before confirming the tag addition?

Stephen, in the success tag use perch_layout and add your perch_member_add_tag() in the layout.

I added prefix="name" to the profile form.

The hidden field now outputs as:

<input id="name_change" name="change" value="true" type="hidden">

I have tried both the following in my script and neither works:

if (isset($_POST['change']) && perch_member_logged_in()) {...
if (isset($_POST['name_change']) && perch_member_logged_in()) {...

It gives an empty array

No, I don't think so.

Double checked and no redirects in place. Cleared my .htaccess and tried again, still no joy.

Is there anything else that could be dropping POST?

That's it - I just had to change next to action. Thank you.