Format array of objects for possible json output for Postman/GET requests

Question

So I can't seem to figure this out, so I'm reaching out to see if someone might be able to help me.

Please let me know what the best output is so that I could use GET to retrieve clean data for the endpoint that I've created.

I have the following method:

function instagram_posts(): bool|string
{
    if (!function_exists('is_plugin_active')) {
        include_once(ABSPATH . 'wp-admin/includes/plugin.php');
    }
    if (!is_plugin_active('fh-instagram/autoload.php')) {
        return false;
    }
    if (empty($items = Instagram::get_items_for_api(50))) {
        return false;
    }
    var_dump($items);

    var_dump(json_encode($items));

    return json_encode($items);
}

var_dump($items); gives me the following output:

array(50) {
  [0]=>
  object(Plugin\Instagram\Item)#976 (7) {
    ["id":"Plugin\Instagram\Item":private]=>
  }
  [1]=>
  object(Plugin\Instagram\Item)#1030 (7) {
    ["id":"Plugin\Instagram\Item":private]=>
    string(17) "17842233125750202"
  }
}

When I run var_dump(json_encode($items)); I get the following output:

string(151) "[{},{}]"

How can I convert my array of objects so that it can transform it to json and then use it within Postman? This is what it currently looks like in Postman:

array(50) {
  [0]=>
  object(Plugin\Instagram\Item)#973 (7) {
    ["id":"Plugin\Instagram\Item":private]=>
    string(17) "17992874035441353"
  }
  [1]=>
  object(Plugin\Instagram\Item)#1027 (7) {
    ["id":"Plugin\Instagram\Item":private]=>
    string(17) "17842233125750202"
  }
}

It should be outputted such as:

[
  {"id": etc..}
]

All help will be appreciated!

The instagram_posts method is being use below:

add_action('rest_api_init', function () {
    register_rest_route( 'instagram', '/posts/', [
        'methods'  => 'GET',
        'callback' => 'instagram_posts',
    ]);
});

So I can use Postman to access the endpoint: http://headlesscms.com.local/wp-json/instagram/posts

Answer 1

Since the property you want is private, it won't be included in the results of json_encode(). Only public properties will.

You need to create a multidimensional array with the structure you want and encode that.

// This is the new array we will push the sub arrays into
$results = [];

foreach($items as $item) {
    $results[] = ['id' => $item->get_id()];
}

return json_encode($results);

This will give you a json structure that looks like:

[
    {
        "id": 1
    },
    {
        "id": 2
    },
    ...
]

Alternative format

If you only want a list of id's, you might not need to create a multidimensional array, but rather just return a list of ids.

In that case, do this:

$results = [];

foreach ($items as $item) {
    $results[] = $item->get_id();
}

return json_encode($results);

That would give you:

[
    1,
    2,
    ...
]