JQUERY & Select box not updating database - php

Question

I have the following 3 checkboxes which are populated from a php database. I need assistance with JQUERY that once any select box is changed the value is posted to a php file and able to return a response through JQUERY.
Each select box should be standalone to only send that checkbox value & name to the PHP file.
I have the below JQUERY to start with to send the first checkbox but am getting no response back.
What amendments need to be made to the JQUERY to receive the input of the other checkboxes and then send the data correctly?
The php file will simply have echo "WHAT EVER THE RESPONSE IS" using if statements.
Any help grately appreciated with thanks.
$(document).ready(function() {
$('select.person-1').change(function() {
$.ajax({
type: 'POST',
url: 'lib/positionMarshalProcess.php',
data: {
selectFieldValue: $('select.person-1').val(),
changeCol1: $('input[name$="changeCol1"]').val()
},
dataType: "html",
},
success: function(data) {
var a = data.split('|***|');
if (a[1] == "update") {
$('#msg').html(a[0]);
}
}
});
return false;
});
});
<script src="https://cdnjs.cloudflare.com/ajax/libs/jquery/3.3.1/jquery.min.js"></script>
<select name='person-1' class='marshal-select'>
<option value='1'>John Smith</option>
</select>
<input type='hidden' name='changeCol1' value='person-1'>
<select name='qty' class='marshal-select'>
<option value='1'>1</option>
</select>
<input type='hidden' name='changeCol2' value='qty'>
<select name='person-2' class='marshal-select'>
<option value='1'>John Smith</option>
</select>
<input type='hidden' name='changeCol3' value='person-2'>

Answer 1

The selectors you've used are incorrect for the HTML displayed. .person-1 is a class selector, yet the select elements have that value in their name.
In addition your success property is outside the options object of the $.ajax call - it needs to be inside.
You can fix this issue and DRY up the code to make it more extensible by removing the hidden fields, hooking the change event handler to the common marshal-select class on all the select elements, and by using the name attribute of the select elements to fill the changeCol property of the data you send in the AJAX request. Try this:
$(document).ready(function() {
$('select.marshal-select').change(function() {
let $select = $(this);
// in your AJAX request...
let data = {
selectFieldValue: $select.val(),
changeCol: $select.prop('name')
};
console.log(data);
});
});
<script src="https://cdnjs.cloudflare.com/ajax/libs/jquery/3.3.1/jquery.min.js"></script>
<select name="person-1" class="marshal-select">
<option value="1">John Smith</option>
<option value="2">Jane Doe</option>
</select>
<select name="qty" class="marshal-select">
<option value="1">1</option>
<option value="2">2</option>
</select>
<select name="person-2" class="marshal-select">
<option value="1">John Smith</option>
<option value="2">Jane Doe</option>
</select>
As an aside, the logic in the success handler implies that you're returning plain text and then hacking the string around using split(). Do not do this. Return a serialised data structure, such as JSON instead. This is more extensible and makes the code far more robust.
Update:
With your code you have added could you just add an edit where how you would receive a response ideally I want a positive response to show the msg div and where you would call the php file?
Sure, here you go:
$(document).ready(function() {
$('select.marshal-select').change(function() {
let $select = $(this);
$.ajax({
type: 'POST',
url: 'lib/positionMarshalProcess.php',
data: {
selectFieldValue: $select.val(),
changeCol: $select.prop('name')
},
dataType: "html",
success: function(data) {
// assuming a JSON response:
if (data[1] === 'update') {
$('#msg').html(data[0]).show();
}
}
});
});
});
Note that I've not included the PHP which would generate the JSON response as I'm not a PHP dev. I'm sure there are lots of topics covering that if you search.