Update Playa field using Charge action

Question

I am using the Charge add-on to connect a website to Stripe payments. I have an action setup whereby a channel entry is created. There are five fields in the channel, four of the fields are text inputs and the last one is a Playa field. The four text inputs are being populated correctly but not the Playa field.

In the code block below, the Playa field is "recipe_purchases_recipe". I am using hidden fields as I only want the form to show the credit card information (removed here for brevity).

This form is embedded in the template as a Stash embed so that I can pass entry variables through. Looking at the code in web inspector I see that the correct variables are coming through, but I can't figure out how to get the Playa field to populate with the entry. I tried {entry_id}, {url_title} and {title} but no luck so far.

How do I populate a Playa field in an entry using the Charge action?

{exp:charge:form
 form_id="charge-form"
 on_success="create_recipe_purchase_entry"
 on_success:recipe_purchases_order_number="{id}"
 on_success:recipe_purchases_customer_name="{customer_name}"
 on_success:recipe_purchases_amount="{plan_amount}"
 on_success:recipe_purchases_recipe="{stash:entry_id}"
 return="/recipes/{segment_2}/thanks"
 return_error="/recipes/{segment_2}/buy"
}
 <input type="hidden" id="customer_name" name="customer_name" value="{exp:zoo_visitor:details}{visitor:member_firstname} {visitor:member_lastname}{/exp:zoo_visitor:details}" />
 <input type="hidden" id="customer_email" name="customer_email" value="{email}" />
 <input type="hidden" id="plan_amount" name="plan_amount" value="{recipe_price}" />
 <input type="hidden" id="recipe_purchases_recipe" name="recipe_purchases_recipe[]" value="{stash:entry_id}" />
   ...       
{/exp:charge:form}

Answer 1

I would say that this is not as easy as using the params for Charge, the problem is Playa is a complex field with its own tables, so it doesn't store the raw value in the exp_channel_data table, but rather stores a reference to the exp_relationships table.

What I would do is develop a small extension that hooks into the charge event action-update-entry-end, set up an action to update your entry as normal (perhaps update a simple field) and use the hook to catch the data you need, from here you can use the Channel Entries API to populate your playa with PHP.