How do I set the value of a custom entries order field from a plugin?

Question

I'm trying to set the value of a custom field on an order when saving an entry. I found an example of how to do this for a simple text field, but the field I'm trying to set is an entries field, not just a text field. I've attempted to set the value using the following code in my entries.saveEntry event. I'm assuming I'm doing this wrong since this is an entries field, not a simple text field, but I don't know the syntax for setting content on an entries field.

$cart = craft()->commerce_cart->getCart();
$cart->setContentFromPost(['entriesFieldHandle' => $entry->id]);

Answer 1

I was close. I was correct in assuming my syntax was incorrect for setting the value of an entries field.

Since an entries field is an array of elements, not just a single element, I just needed to set the value of the field as an array instead of a string.

Changing

$cart->setContentFromPost(['entriesFieldHandle' => $entry->id]);

to

$cart->setContentFromPost(['entriesFieldHandle' => [$entry->id]]);

seemed to do the trick.

To zoom in a little more, the value needs to be set with 'entriesFieldHandle' => [$entry->id] instead of 'entriesFieldHandle' => $entry->id.