WooCommerce Add To Cart Form Shortcode that supports variable products too

add-to-cart-form-shortcode.php

add_shortcode( 'add-to-cart-form', function($atts) {
	global $post;

	//Get shortcode attributes
	$a = shortcode_atts( array(
		'id' => 0
	), $atts );

	//Find the product and set it to global
	$product_data = get_post( $a['id'] );
	$product = is_object( $product_data ) && in_array( $product_data->post_type, array( 'product', 'product_variation' ), true ) ? wc_setup_product_data( $product_data ) : false;

	//If its not a product, return nothing
	if ( ! $product ) {
		return '';
	}

	//This will render the add to cart form
	do_action( 'woocommerce_' . $product->get_type() . '_add_to_cart' );

	//Reset global $post
	wc_setup_product_data( $post );
});

I've added some code to render the form in the right place, especially if you use a visual editor.

// This will render the add to cart form
ob_start();
do_action( 'woocommerce_' . $product->get_type() . '_add_to_cart' );
$add_to_cart_content = ob_get_clean();
return $add_to_cart_content;