PHPで金価格APIを使う：cURL、Guzzle、WordPressショートコード

{
  "success": true,
  "timestamp": 1792834892,
  "date": "2026-10-24",
  "base": "USD",
  "rates": {
    "XAU": 0.0002501319,
    "USDXAU": 3997.89,
    "EUR": 0.8925,
    "USDEUR": 1.1204
  },
  "rate_limit": { "...": "..." }
}

<?php
// PHP 8以降とcurl拡張モジュールが必要。実行：METALAPI_KEY=mk_live_... php gold.php
function metalapi(string $path, array $params = []): array
{
    $ch = curl_init('https://metalapi.com/api/v1/' . $path . '?' . http_build_query($params));
    curl_setopt_array($ch, [
        CURLOPT_RETURNTRANSFER => true,
        CURLOPT_CONNECTTIMEOUT => 5,
        CURLOPT_TIMEOUT        => 10,
        CURLOPT_HTTPHEADER     => ['X-API-Key: ' . getenv('METALAPI_KEY')],
    ]);
    $body = curl_exec($ch);
    if ($body === false) {
        throw new RuntimeException('Network error: ' . curl_error($ch));
    }
    $status = curl_getinfo($ch, CURLINFO_RESPONSE_CODE);
    $data = json_decode($body, true);
    if (empty($data['success'])) {
        $code = $data['error']['code'] ?? $status;
        $info = $data['error']['info'] ?? "HTTP $status";
        throw new RuntimeException("MetalAPI $code: $info", $code);
    }
    return $data;
}

$data = metalapi('latest', ['base' => 'USD', 'currencies' => 'XAU']);
printf("Gold: %.2f USD per troy oz\n", $data['rates']['USDXAU']);
printf("Time: %s UTC\n", gmdate('Y-m-d H:i', $data['timestamp']));

<?php
// composer require guzzlehttp/guzzle
require __DIR__ . '/vendor/autoload.php';

$client = new GuzzleHttp\Client([
    'base_uri'    => 'https://metalapi.com/api/v1/',
    'timeout'     => 10,
    'http_errors' => false,
    'headers'     => ['X-API-Key' => (string) getenv('METALAPI_KEY')],
]);

$res  = $client->get('latest', ['query' => ['base' => 'EUR', 'currencies' => 'XAU', 'unit' => 'gram']]);
$data = json_decode((string) $res->getBody(), true);

if (empty($data['success'])) {
    $code = $data['error']['code'] ?? $res->getStatusCode();
    throw new RuntimeException("MetalAPI $code: " . ($data['error']['info'] ?? $res->getReasonPhrase()), $code);
}
printf("Gold: %.2f EUR per gram\n", $data['rates']['EURXAU']);

define( 'METALAPI_KEY', 'mk_live_your_key_here' );

<?php
/**
 * Plugin Name:  MetalAPI Gold Price
 * Description:  [gold_price] shortcode, cached in a transient and refreshed by WP-Cron.
 * Requires PHP: 8.0
 */
defined( 'ABSPATH' ) || exit;

const MGP_INTERVAL   = 600;              // 秒。Standard：600、Lite：3600、Free：86400
const MGP_CURRENCIES = [ 'EUR', 'GBP' ]; // USD以外に、ショートコードで使うすべての通貨
const MGP_GRAMS      = [ 'troy_oz' => 31.1034768, 'gram' => 1, 'kilogram' => 1000 ];

function mgp_refresh(): ?array {
    if ( ! defined( 'METALAPI_KEY' ) ) {
        return null;
    }
    $url  = add_query_arg(
        [ 'base' => 'USD', 'currencies' => implode( ',', [ 'XAU', ...MGP_CURRENCIES ] ) ],
        'https://metalapi.com/api/v1/latest'
    );
    $res  = wp_remote_get( $url, [ 'timeout' => 8, 'headers' => [ 'X-API-Key' => METALAPI_KEY ] ] );
    $data = is_wp_error( $res ) ? null : json_decode( wp_remote_retrieve_body( $res ), true );

    if ( empty( $data['success'] ) ) {
        error_log( 'MetalAPI refresh failed: ' . ( is_wp_error( $res ) ? $res->get_error_message() : wp_remote_retrieve_body( $res ) ) );
        $last = get_option( 'mgp_prices_last' );
        if ( $last ) {
            set_transient( 'mgp_prices', $last, 5 * MINUTE_IN_SECONDS ); // 間隔を空け、最後に取得できた価格を維持する
        }
        return $last ?: null;
    }

    $per_oz = [ 'USD' => $data['rates']['USDXAU'] ];
    foreach ( MGP_CURRENCIES as $cur ) {
        if ( ! empty( $data['rates'][ "USD$cur" ] ) ) {
            $per_oz[ $cur ] = $data['rates']['USDXAU'] / $data['rates'][ "USD$cur" ];
        }
    }
    $prices = [ 'per_oz' => $per_oz, 'time' => $data['timestamp'] ];
    set_transient( 'mgp_prices', $prices, 2 * MGP_INTERVAL ); // cronの実行が1回遅れても残る
    update_option( 'mgp_prices_last', $prices, false );       // Transientが追い出された場合の予備
    return $prices;
}

function mgp_prices(): ?array {
    return get_transient( 'mgp_prices' ) ?: mgp_refresh();
}

add_shortcode( 'gold_price', function ( $atts ): string {
    $a    = shortcode_atts( [ 'currency' => 'USD', 'unit' => 'troy_oz', 'decimals' => 2 ], $atts, 'gold_price' );
    $cur  = strtoupper( $a['currency'] );
    $unit = strtolower( $a['unit'] );
    $p    = mgp_prices();
    if ( ! $p || ! isset( $p['per_oz'][ $cur ] ) || ! array_key_exists( $unit, MGP_GRAMS ) ) {
        return '';
    }
    $price = $p['per_oz'][ $cur ] / MGP_GRAMS['troy_oz'] * MGP_GRAMS[ $unit ];
    return sprintf(
        '<span class="gold-price">%s %s / %s</span> <small>%s</small>',
        esc_html( number_format_i18n( $price, absint( $a['decimals'] ) ) ),
        esc_html( $cur ),
        esc_html( str_replace( '_', ' ', $unit ) ),
        esc_html( wp_date( get_option( 'date_format' ) . ' ' . get_option( 'time_format' ), $p['time'] ) )
    );
} );

// WP-Cron：間隔ごとに1回、バックグラウンドで更新する。
add_filter( 'cron_schedules', function ( array $schedules ): array {
    $schedules['mgp_interval'] = [ 'interval' => MGP_INTERVAL, 'display' => 'MetalAPI refresh' ];
    return $schedules;
} );
add_action( 'mgp_refresh_event', 'mgp_refresh' );

register_activation_hook( __FILE__, function (): void {
    if ( ! wp_next_scheduled( 'mgp_refresh_event' ) ) {
        wp_schedule_event( time(), 'mgp_interval', 'mgp_refresh_event' );
    }
} );
register_deactivation_hook( __FILE__, function (): void {
    wp_clear_scheduled_hook( 'mgp_refresh_event' );
} );

*/10 * * * * cd /var/www/html && wp cron event run --due-now > /dev/null 2>&1

<div id="metalapi-widget-w_abc123"></div>
<script src="https://metalapi.com/js/widget.js" data-widget="w_abc123" async></script>