Hi folks -- the Fulfillment resource includes a list of line items corresponding to what part of the order this fulfillment is responsible for. The `id` on each of the `line_items` is for an order line item. Because the same order line item can be partially fulfilled more than once, there can be multiple fulfillment line items for the same order line item! So, there is a separate fulfillment line item id that uniquely addresses the maybe-partial quantity of the order line item being fulfilled.
When you ask for the Fulfillment resource in the REST API, you get both an `id` and `fulfillment_line_item_id` for each entry in the `line_items` array. But, when you get a fulfillment webhook (or order webhook), that `fulfillment_line_item_id` attribute is missing. The ID of the fulfillment line item is also available in the GraphQL API too.
How are you supposed to get this data if you want to track a fulfillment in another system, or even just show a row to the merchant in the Shopify app? Make a request back to Shopify for every incoming webhook? I feel like that's a good way to totally exhaust your rate limit in a situation where many fulfillments are being updated at once, like a flash sale or import.
Could we get the `fulfillment_line_item_id` attribute from the REST API added to the webhook payload? It'd be so easy for shopify and is so much work for us on the outside without it!