Add a Contact Form to “Out of Stock” product Variations in WooCommerce

I have successfully added a contact form to a product if it is Out of Stock using

add_action('woocommerce_single_product_summary', 'add_contact_form', 30,2);

function add_contact_form() {
    global $product;
        if(!$product->is_in_stock( )) {
           echo do_shortcode('[contact-form-7 id="6513" title="Out of Stock Form"]');
        }
    }

But I also want to add the same form if a products variation is Out of Stock too. Just unsure as to which hook I can use to tie it in to the Out of Stock message for that variation… I feel like it may be something to do with line 20 of woocommerce/single-product/add-to-cart/variation.php

<div class="woocommerce-variation-availability">{{{ data.variation.availability_html }}}</div>

But am getting a bit lost TBH.

I can change the text that is diaplyed for both simple products and those with variations by using

add_filter( 'woocommerce_get_availability', 'wcs_custom_get_availability', 1, 2);

function wcs_custom_get_availability( $availability, $_product ) {

    if ( ! $_product->is_in_stock() ) {
        $availability['availability'] = __('<h4 style="color:#F00;">Coming Soon</h4>', 'woocommerce');
    }

    return $availability;
    }

But if I try and add the Form Shortcode or other HTML, like an iFrame, it is stripped out and does not render.

Answer

The following code will add a contact form to a selected out of stock product variation:

add_filter( 'woocommerce_available_variation', 'form_to_out_of_stock_product_variations', 10, 3 );
function form_to_out_of_stock_product_variations( $data, $product, $variation ) {
    if( ! $data['is_in_stock'] )
        $data['availability_html'] .= do_shortcode('[contact-form-7 id="6513" title="Out of Stock Form"]');

    return $data;
}

Code goes in function.php file of your active child theme (or active theme). Tested and works.

---

So you will need to tweak your existing code as follow:

add_action('woocommerce_single_product_summary', 'add_contact_form', 30,2);
function add_contact_form() {
    global $product;

    if( ! $product->is_in_stock( ) && ! $product->is_type('variable') )
       echo do_shortcode('[contact-form-7 id="6513" title="Out of Stock Form"]');
}

Code goes in function.php file of your active child theme (or active theme). Tested and works