Create programmatically a WooCommerce product variation with new attribute values

Update January 2020: Changed to WC_Product method get_name() instead of get_title()
Update September 2018: Handling taxonomy creation (Thanks to Carl F. Corneil)

From a defined variable product ID You will find below, a custom function that will add (create) a Product variation. The variable parent product needs to have set for it the needed attributes.

You will need to provide some information as:

• the array of attributes/values
• the Sku, prices and stock….

This data has to be stored in a formatted multi dimensional array (see an example at the end).

This function will check if the attributes values (term name) already exist and if not:

• it create it for the product attribute
• set it in the parent variable product.

The custom function code:

/**
 * Create a product variation for a defined variable product ID.
 *
 * @since 3.0.0
 * @param int   $product_id | Post ID of the product parent variable product.
 * @param array $variation_data | The data to insert in the product.
 */

function create_product_variation( $product_id, $variation_data ){
    // Get the Variable product object (parent)
    $product = wc_get_product($product_id);

    $variation_post = array(
        'post_title'  => $product->get_name(),
        'post_name'   => 'product-'.$product_id.'-variation',
        'post_status' => 'publish',
        'post_parent' => $product_id,
        'post_type'   => 'product_variation',
        'guid'        => $product->get_permalink()
    );

    // Creating the product variation
    $variation_id = wp_insert_post( $variation_post );

    // Get an instance of the WC_Product_Variation object
    $variation = new WC_Product_Variation( $variation_id );

    // Iterating through the variations attributes
    foreach ($variation_data['attributes'] as $attribute => $term_name )
    {
        $taxonomy = 'pa_'.$attribute; // The attribute taxonomy

        // If taxonomy doesn't exists we create it (Thanks to Carl F. Corneil)
        if( ! taxonomy_exists( $taxonomy ) ){
            register_taxonomy(
                $taxonomy,
               'product_variation',
                array(
                    'hierarchical' => false,
                    'label' => ucfirst( $attribute ),
                    'query_var' => true,
                    'rewrite' => array( 'slug' => sanitize_title($attribute) ), // The base slug
                ),
            );
        }

        // Check if the Term name exist and if not we create it.
        if( ! term_exists( $term_name, $taxonomy ) )
            wp_insert_term( $term_name, $taxonomy ); // Create the term

        $term_slug = get_term_by('name', $term_name, $taxonomy )->slug; // Get the term slug

        // Get the post Terms names from the parent variable product.
        $post_term_names =  wp_get_post_terms( $product_id, $taxonomy, array('fields' => 'names') );

        // Check if the post term exist and if not we set it in the parent variable product.
        if( ! in_array( $term_name, $post_term_names ) )
            wp_set_post_terms( $product_id, $term_name, $taxonomy, true );

        // Set/save the attribute data in the product variation
        update_post_meta( $variation_id, 'attribute_'.$taxonomy, $term_slug );
    }

    ## Set/save all other data

    // SKU
    if( ! empty( $variation_data['sku'] ) )
        $variation->set_sku( $variation_data['sku'] );

    // Prices
    if( empty( $variation_data['sale_price'] ) ){
        $variation->set_price( $variation_data['regular_price'] );
    } else {
        $variation->set_price( $variation_data['sale_price'] );
        $variation->set_sale_price( $variation_data['sale_price'] );
    }
    $variation->set_regular_price( $variation_data['regular_price'] );

    // Stock
    if( ! empty($variation_data['stock_qty']) ){
        $variation->set_stock_quantity( $variation_data['stock_qty'] );
        $variation->set_manage_stock(true);
        $variation->set_stock_status('');
    } else {
        $variation->set_manage_stock(false);
    }
    
    $variation->set_weight(''); // weight (reseting)

    $variation->save(); // Save the data
}

Code goes in function.php file of your active child theme (or theme) or also in any plugin file.

Usage (example with 2 attributes):

$parent_id = 746; // Or get the variable product id dynamically

// The variation data
$variation_data =  array(
    'attributes' => array(
        'size'  => 'M',
        'color' => 'Green',
    ),
    'sku'           => '',
    'regular_price' => '22.00',
    'sale_price'    => '',
    'stock_qty'     => 10,
);

// The function to be run
create_product_variation( $parent_id, $variation_data );

Tested and works.

Part 2: Create programmatically a variable product and two new attributes in WooCommerce

You will get this in backend:

And it will work perfectly in front end.

Related: Create programmatically a product using CRUD methods in Woocommerce 3

I'm just going to throw this out there, since i couldn't get any of the above examples working. Don't ask me why as other people seem to have success. So, i took the minimalist approach and tried to figure out the bare essentials for a product attribute + variation (by creating it manually in wp and looking at the db) and came up with this.

$article_name = 'Test';

$post_id = wp_insert_post( array(
    'post_author' => 1,
    'post_title' => $article_name,
    'post_content' => 'Lorem ipsum',
    'post_status' => 'publish',
    'post_type' => "product",
) );
wp_set_object_terms( $post_id, 'variable', 'product_type' );

$attr_label = 'Test attribute';
$attr_slug = sanitize_title($attr_label);

$attributes_array[$attr_slug] = array(
    'name' => $attr_label,
    'value' => 'alternative 1 | alternative 2',
    'is_visible' => '1',
    'is_variation' => '1',
    'is_taxonomy' => '0' // for some reason, this is really important       
);
update_post_meta( $post_id, '_product_attributes', $attributes_array );

$parent_id = $post_id;
$variation = array(
    'post_title'   => $article_name . ' (variation)',
    'post_content' => '',
    'post_status'  => 'publish',
    'post_parent'  => $parent_id,
    'post_type'    => 'product_variation'
);

$variation_id = wp_insert_post( $variation );
update_post_meta( $variation_id, '_regular_price', 2 );
update_post_meta( $variation_id, '_price', 2 );
update_post_meta( $variation_id, '_stock_qty', 10 );
update_post_meta( $variation_id, 'attribute_' . $attr_slug, 'alternative 1' );
WC_Product_Variable::sync( $parent_id );

$variation_id = wp_insert_post( $variation );
update_post_meta( $variation_id, '_regular_price', 2 );
update_post_meta( $variation_id, '_price', 2 );
update_post_meta( $variation_id, '_stock_qty', 10 );
update_post_meta( $variation_id, 'attribute_' . $attr_slug, 'alternative 2' );
WC_Product_Variable::sync( $parent_id );

This is not using global product attributes, but article specific ones. Hope it helps someone as i was about ready to tear my hair out before i got it working.

EDIT: I'd say only use this if you can't get the official methods working. They change these things with time (field names such as '_regular_price" and so on) and chances are it's not super future proof to do it this way.

Not sure why, but none of these solutions worked for me, so I decided to create my own:

<?php
/**
 * Create a variable product on woocommerce
 * @return int Product ID
 */
function pricode_create_product(){
    $product = new WC_Product_Variable();
    $product->set_description('T-shirt variable description');
    $product->set_name('T-shirt variable');
    $product->set_sku('test-shirt');
    $product->set_price(1);
    $product->set_regular_price(1);
    $product->set_stock_status();
    return $product->save();
}

/**
 * Create Product Attributes 
 * @param  string $name    Attribute name
 * @param  array $options Options values
 * @return Object          WC_Product_Attribute 
 */
function pricode_create_attributes( $name, $options ){
    $attribute = new WC_Product_Attribute();
    $attribute->set_id(0);
    $attribute->set_name($name);
    $attribute->set_options($options);
    $attribute->set_visible(true);
    $attribute->set_variation(true);
    return $attribute;
}

/**
 * [pricode_create_variations description]
 * @param  [type] $product_id [description]
 * @param  [type] $values     [description]
 * @return [type]             [description]
 */
function pricode_create_variations( $product_id, $values, $data ){
    $variation = new WC_Product_Variation();
    $variation->set_parent_id( $product_id );
    $variation->set_attributes($values);
    $variation->set_status('publish');
    $variation->set_sku($data->sku);
    $variation->set_price($data->price);
    $variation->set_regular_price($data->price);
    $variation->set_stock_status();
    $variation->save();
    $product = wc_get_product($product_id);
    $product->save();

}
//Adding product
$product = pricode_create_product();

//Creating Attributes 
$atts = [];
$atts[] = pricode_create_attributes('color',['red', 'green']);
$atts[] = pricode_create_attributes('size',['S', 'M']);

//Adding attributes to the created product
$product->set_attributes( $atts );
$product->save();

//Setting data (following Alexander's rec
$data = new stdClass();
$data->sku = 'sku-123';
$data->price = '10';
//Create variations
pricode_create_variations( $product->get_id(), ['color' => 'red', 'size' => 'M'], $data );

Hope it can help others.

Expanding on LoicTheAztec's answer, you can check if the attribute combination exists with the following modification to his code.

function create_update_product_variation( $product_id, $variation_data ){

    if(isset($variation_data['variation_id'])) {

      $variation_id = $variation_data['variation_id'];

    } else {

      // if the variation doesn't exist then create it

      // Get the Variable product object (parent)
      $product = wc_get_product($product_id);

      $variation_post = array(
          'post_title'  => $product->get_title(),
          'post_name'   => 'product-'.$product_id.'-variation',
          'post_status' => 'publish',
          'post_parent' => $product_id,
          'post_type'   => 'product_variation',
          'guid'        => $product->get_permalink()
      );

      // Creating the product variation
      $variation_id = wp_insert_post( $variation_post );

    }

    // ...

}

Example usage

// The variation data
$variation_data =  array(
    'attributes' => array(
        'size'  => 'M',
        'color' => 'Green',
    ),
    'sku'           => '',
    'regular_price' => '22.00',
    'sale_price'    => '1',
    'stock_qty'     => 1,
);

// check if variation exists
$meta_query = array();
foreach ($variation_data['attributes'] as $key => $value) {
  $meta_query[] = array(
    'key' => 'attribute_pa_' . $key,
    'value' => $value
  );
}

$variation_post = get_posts(array(
  'post_type' => 'product_variation',
  'numberposts' => 1,
  'post_parent'   => $parent_id,
  'meta_query' =>  $meta_query
));

if($variation_post) {
  $variation_data['variation_id'] = $variation_post[0]->ID;
}

create_update_product_variation( $product_id, $variation_data );