How to import metafields with product api in php

Shopify Apps
1

Someone please help me to import product additional information as metafield in product import api using php.

In my case:

  1. If the metafield does not exist, create it.

  2. If the metafield value does not exist, add it.

  3. Add the metafield to the product to be visible in the product page.

Thank you