Get a specific product with Element API, Commerce and Craft 2

Question

How do I get a specific product via Element API?

Here's what i have so far

'api/product' => function() {
    $productId = craft()->request->getRequiredQuery( 'productId' );

    return [
        'elementType' => Product::class,
        // This provides Element API the fully qualified Element namespace + class.
        'pretty'      => true,
        'criteria'    => [
            'relatedTo' => [ 'targetElement' => $categoryIds ],
        ],
        'transformer' => function( Product $product ) {
            return [
                'title' => $product->title,
                'url'   => $product->url
            ];
        }

    ];
}   

Answer 1

If you want to get a specific product and it's variants by the productId you could simply do:

'api/product/<productId>' => function( $productId ) {
    return [
        'elementType' => Product::class,
        'criteria'    => [
            'id' => $productId
        ],
        'pretty'      => true,
        'transformer' => function( Product $product ) {
            foreach ( $product->getVariants() as $variant ) {
                $variants = [
                    'title'         => $variant->title,
                    'description'   => $variant->description,
                    'productId'     => (int) $variant->productId,
                    'purchasableId' => (int) $variant->purchasableId,
                    'status'        => $variant->status,
                    'type'          => $product->type->name,
                    'url'           => $product->url,
                ];
            }

            return $variants;
        },
    ];
},

you are able to get the product then via yourshop.domain/product/1234