Send search term and custom flag to php function via Ajax - php

Question

I'm looking for a way to filter autocomplete results if the custom flag is sent to function, together with the search term. For example, if the user wants to find all cities that have stadium/swimming pool, etc. he can pick this as a filtering option.
var filter = $.inArray('1', selectedTypes);
This line searches only one flag to see if it's working
I have autocomplete set up and working fine without the filter, but now I'm not sure how to set it up. Any help is appreciated.
jQuery:
$('#city').autocomplete({
delay: 0,
source: function (request, response) {
var selectedTypes = $("#filter").val();
var filter = $.inArray('1', selectedTypes);
$.ajax({
url: "/cities/ajaxGetCities/" + request.term,
dataType: "json",
contentType: "application/json",
success: function (data) {
if (typeof(data[0]) === 'undefined') {
return null;
}
response($.map(data, function (value, key) {
return {
label: value.cityName,
value: value.id
}
}));
}
});
},
select: function (event, ui) {
$("#city").val(ui.item.label);
return false;
},
autoFocus: true
});
PHP (in controller, using CodeIgniter):
public function ajaxGetCities(string $term, int $filter = null)
{
if ($filter) {
$cities = getFilteredCities($filter)
} else {
$cities = getCities($term);
}
$filteredCities = [];
foreach ($cities as $city) {
if (stripos($city->cityName, $term) !== false ) {
$filteredCities[] = $city;
}
}
exit(json_encode($filteredCities));
}
I tried this in JS, and removed func arguments in controller but the $_POST was empty
$.ajax({
type: 'POST',
data: {term: request.term, flag: filter},
url: "/cities/ajaxGetCities",
dataType: "json",
contentType: "application/json",
success: function (data) {
if (typeof(data[0]) === 'undefined') {
return null;
}
response($.map(data, function (value, key) {
return {
label: value.cityName,
value: value.id
}
}));

Answer 1

"the $_POST was empty"
...this is because you send the data as JSON, due to specifying
contentType: "application/json"
in the AJAX options. But what is the server expecting? By default PHP expects normal form data, not JSON. If you send JSON, a little bit of extra code is needed to process it.
If you simply remove that line from your AJAX options, the data will be sent as form data (the default) and PHP should be able read it happily as standard POST variables.