Discount based on a field in product display node in Drupal Commerce?

Question

I want to create a pricing rule based on discount entered in a field in the product display node? Is it possible? I have been trying to do it but i can't see the discount field in the dataselector. I tried entity has field but there only line-item entity appears and no node entity?

Answer 1

You can do this, I have done so myself. It's been a lot easier to do this than when I needed to do this.

The thing is that in rules, in order to get the fields of an entity, to use it in Rules, you need to either add a condition that the field exists or add a condition that the entity is of type X.

I've attached the base setup that does this for the commerce kickstart install profile. You might be using a different product type, but it should be easy to change.

{ "rules_example_discount" : {
    "LABEL" : "Example discount",
    "PLUGIN" : "reaction rule",
    "REQUIRES" : [ "rules", "commerce_product_reference" ],
    "ON" : [ "commerce_product_calculate_sell_price" ],
    "IF" : [
      { "data_is" : { "data" : [ "commerce-line-item:type" ], "value" : "product" } },
      { "data_is" : {
          "data" : [ "commerce-line-item:commerce-product:type" ],
          "value" : "product"
        }
      }
    ],
    "DO" : []
  }
}

Update:

Since you are saving the discount on the product display, you are making it more difficult for you. What you need to do, is from the line_item/product context to be able to figure out which product display the product comes from. The easiest way to do that would be to add a node reference field on the line item and then populate that with the product display node when adding the product to the cart. This should be doable with a custom submit handler added to the add to cart form with hook_form_alter. Then you need to tweak the rule accordingly and use the field from the node referenced on the line item instead of the product reference on the line item.

Answer 2

As I said on IRC, a line item doesn't store the id of the product display in a way that Rules can understand. This is because product displays are not required for Commerce to work.

However, line items have a "commerce_display_path" field that stores the url from which the product was added, so in your case it would probably look like "node/1", or whatever the node id is.

What you need to do is: Write a custom Rules action that takes the line item, initializes the wrapper, gets the value of commerce_display_path, explodes the string, takes the nid, loads the node, returns it.

Example code:
$line_item_wrapper = entity_metadata_wrapper('commerce_line_item', $commerce_line_item);
$url = $line_item_wrapper->commerce_display_path->value();
$url_parts = explode('/', $url);
$nid = $url_parts[1];
return array('node_fetched' => $node);

Place this in a custom rules action, and you're good to go.

You can then use your action in a component to get the product display whose fields you can then access.