Trouble filtering API results with PHP/conditionals

Question

First, apologies in advance for what may be a pretty green question! I'm only just getting the hang of PHP, and there's not a ton of support out there for APIs...

I'm currently trying to filter some listing results I've returned using the Etsy API. I'd like to limit them to only specific category or taxonomy ID, but none of the PHP conditionals I'm using seem to be returning any results. A few of the things I've tried so far:

<?php

define("API_KEY", XXX);

$url = "https://openapi.etsy.com/v2/listings/active?tags=unicorn,unicorns&keywords=unicorn,unicorns&includes=Images:1:0&api_key=" . API_KEY;

while (isset($url) && $url != '' && $next_page < 3) {

$curl = curl_init($url);
curl_setopt($curl, CURLOPT_RETURNTRANSFER, 1);
$response_body=curl_exec($curl);
curl_close($curl);

$response = json_decode($response_body);

$taxo = $response->results->taxonomy_id;

if($taxo == 66) {

    foreach ($response->results as $listing) {
            echo "<li>"
            . '<a href="' . $listing->url . '" target="_blank"><img src="' . $listing->Images[0]->url_170x135 . '" alt=""></a>'
            . "<p>" . $listing->title . "</p>"
            . "<p>~*~" . $listing->price . " " . $listing->currency_code . "~*~</p>" .
            $listing->taxonomy_id .
            "</li>";
}
} else {
    echo "NO RESULTS";
}

$next_page = $response->pagination->next_page;
$baseUrl = "https://openapi.etsy.com/v2/listings/active?tags=unicorn,unicorns&keywords=unicorn,unicorns&includes=Images:1:0&api_key=" . API_KEY . "&page=";
$url = $baseUrl . $next_page;

}

?>

I've tried both for and while here:

<?php

define("API_KEY", XXX);

$url = "https://openapi.etsy.com/v2/listings/active?tags=unicorn,unicorns&keywords=unicorn,unicorns&includes=Images:1:0&api_key=" . API_KEY;

if(isset($url) && $url != '' && $next_page < 3 && $taxo == 66) {

$curl = curl_init($url);
curl_setopt($curl, CURLOPT_RETURNTRANSFER, 1);
$response_body=curl_exec($curl);
curl_close($curl);

$response = json_decode($response_body);

$taxo = $response->results->taxonomy_id;

foreach ($response->results as $listing) {
    echo "<li>"
    . '<a href="' . $listing->url . '" target="_blank"><img src="' . $listing->Images[0]->url_170x135 . '" alt=""></a>'
    . "<p>" . $listing->title . "</p>"
    . "<p>~*~" . $listing->price . " " . $listing->currency_code . "~*~</p>" .
    $listing->taxonomy_id .
    "</li>";
}

$next_page = $response->pagination->next_page;
$baseUrl = "https://openapi.etsy.com/v2/listings/active?tags=unicorn,unicorns&keywords=unicorn,unicorns&includes=Images:1:0&api_key=" . API_KEY . "&page=";
$url = $baseUrl . $next_page;

var_dump($url);

}

else {
echo "NO RESULTS";
}

?>

I feel like I'm missing something obvious here, but I'm super stuck. Any guidance on what I'm doing wrong?

---

Sample responses returned for a listing using the call included in above code:

results:

[ 
{ listing_id: 264154010, state: "active", user_id: 22167794, category_id: 69190377, title: "Swim with Mermaids print, hand lettering, watercolor, green blue purple", creation_tsz: 1452898819, ending_tsz: 1463349619, original_creation_tsz: 1452898657, last_modified_tsz: 1452898849, price: "10.00", currency_code: "USD", quantity: 15, tags: 
[ "rainbows", "unicorns", "fairies", "mermaids", "purple ", "blue", "green", "hand lettering", "abstract", "lettering", "hand", "watercolor" ], category_path: 
[ "Art", "Print", "Giclee" ], category_path_ids: 
[ 68887312, 68892154, 69190377 ], url: "https://www.etsy.com/listing/264154010/swim-with-mermaids-print-hand-lettering?utm_source=funappyay&utm_medium=api&utm_campaign=api", taxonomy_id: 121, taxonomy_path: 
[ "Art & Collectibles", "Prints", "Giclee" ], }, 
{ listing_id: 234448248, state: "active", user_id: 30961143, category_id: 68887486, title: "Keep Calm and Hug Me Baby Blanket Afghan Crochet PATTERN by Peach.Unicorn", creation_tsz: 1452898542, ending_tsz: 1463349342, original_creation_tsz: 1432388408, last_modified_tsz: 1452898542, price: "1.99", currency_code: "GBP", quantity: 41, tags: 
[ "Baby", "Blanket", "Crochet", "Crochet Pattern", "Blanket Pattern", "Keep Calm", "Puff Stitch", "Baby Blanket", "Instant download", "baby girl", "baby boy", "hug me", "dk yarn pattern" ], category_path: 
[ "Patterns" ], category_path_ids: 
[ 68887486 ], url: "https://www.etsy.com/listing/234448248/keep-calm-and-hug-me-baby-blanket-afghan?utm_source=funappyay&utm_medium=api&utm_campaign=api", taxonomy_id: 729, taxonomy_path: 
[ "Craft Supplies & Tools", "Patterns & Tutorials" ], },

Answer 1

All right, I figured it out! In case anyone else is looking for the answer in the future, my somewhat messy solution:

<?php

define("API_KEY", XXX);

$url = "https://openapi.etsy.com/v2/listings/active?tags=unicorn,unicorns&keywords=unicorn,unicorns&includes=Images:1:0&api_key=" . API_KEY;

while(isset($url) && $url != '') {

    $curl = curl_init($url);
    curl_setopt($curl, CURLOPT_RETURNTRANSFER, 1);
    $response_body=curl_exec($curl);
    curl_close($curl);

    $response = json_decode($response_body);

        foreach ($response->results as $listing) {

                $taxo = $listing->taxonomy_id;

                if($taxo == 41 || $taxo == 873){
                    echo '<li><a href="'
                    . $listing->url .
                    '" target="_blank"><img src="'
                    . $listing->Images[0]->url_170x135 .
                    '" alt=""></a>'
                    . "<p>" . $listing->title . "</p>"
                    . "<p>~*~" . $listing->price . " " . $listing->currency_code . "~*~</p>" .
                    $taxo . '</li>';
                }
        }

    $next_page = $response->pagination->next_page;
    $baseUrl = "https://openapi.etsy.com/v2/listings/active?tags=unicorn,unicorns&keywords=unicorn,unicorns&includes=Images:1:0&api_key=" . API_KEY . "&page=";
    $url = $baseUrl . $next_page;

}

?>

Still struggling a little with understanding why setting $taxo outside of the foreach loop was unsuccessful, so any insight there is still appreciated.