This problem is to do with the following modules:

  • Drupal Commerce
  • Rules
  • Entity

I have the following code in an "Execute custom PHP code" Rules action. It creates a product display to go with a product (also created by Rules).

The problem is, it does not populate the product reference field (field_product_reference) and gives an error.


$product = $contact_details_product;
$display = new stdClass();
$display->type = 'product_display_regular';

$display->title  = "Product display";
$display->language = LANGUAGE_NONE;

$display->field_product_reference['und'][0]['product_id'] = $product->product_id;
echo "TYPE: " . gettype($product->product_id);


  • $contact_details_product is a variable available in Rules due to the previously created 'product' (as opposed to the display). This product was created in the same rule by a previous action.
  • product_display_regular is the product display content type.
  • field_product_reference is the machine name of the product reference field.


Warning: array_flip() [function.array-flip]: Can only flip STRING and INTEGER values! in DrupalDefaultEntityController->load() (line 178 of /home/test/public_html/includes/entity.inc).

Hacking entity.inc to display some values showed that at some point the variable on line 178 gets a null value, so I'm guessing there's a problem with the php code in the rule. Output of gettype and print_r in entity.inc:

TYPE: string
Array ( [0] => 170 )
TYPE: string
Array ( [0] => 170 )
Array ( [0] => )

That's about all I have right now. Can give more info if needed. Cheers!

2 Answers 2


On further investigation it seems that the product created by Rules (in the previous action) is not assigning a product_id in the first place. Therefore there is nothing to assign to the 'product display'.

(I still don't understand why this is happening but rather than change this question completely I will post a new question.)


This work-around will do what you need using Drupal 7 database abstraction layer: This code is from a module I wrote to create product displays from an XML feed:

  $title_result = db_query('SELECT title FROM {commerce_product} WHERE product_id = :product_id', array(':product_id' => $prodid))->fetchField(); 
$node = new stdClass();
$node->title = $title_result;
$node->type = 'product_display';

$node->language = LANGUAGE_NONE;
$node->uid = $user->uid; 
$node->status = 1; //(1 or 0): published or not
$node->promote = 0; //(1 or 0): promoted to front page
$node->comment = 1; // 0 = comments disabled, 1 = read only, 2 = read/write
$node->field_product['und'][0]['product_id'] = $prodid;
$node = node_submit($node); // Prepare node for saving
drupal_set_message( "Product Display for " . $prodid . " created.\n");

Obviously some variables are in my code that are not accounted for but hopefully it will be clear what I did.

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