EntityMetadataWrapperException: Unable to get the data property currency_code as the parent data structure is not set. in Entity

Not enough info here; bug reports need to be reproducible, such as "I installed this module" or "I setup this rule." If this is a vanilla install, try using Commerce Repair to see if a field got missed on installation (though that sort of thing has been happening less and less).

i also had a similar problem but the 'currency code' in my case is just 'data' svolved it halfway i think.
since i got the same error when adding to cart and trying to view orders,
i went into the database and whiped clean/did a TRUNCATE on the order spesific tables:

commerce_order
commerce_order_revision
field_data-commerce_order_total
field_revision_commerce_order_total

(!note: deletes current order data.)

and the cart and orders works fine again!

but suddenly i got problems with search_api_index at the 'view all products page'.
And now after i removed the indexes with UI to rebuild again,
i get the same damn error!? when trying to rebuild (..or run cron)

the error:

An AJAX HTTP error occurred. HTTP Result Code: 500 Debugging information follows. Path: /batch?id=154&op=do StatusText: Service unavailable (with message) ResponseText: EntityMetadataWrapperException: Unable to get the data property as the parent data structure is not set. in EntityStructureWrapper->getPropertyValue() (line 442 of /home4/brevisfo/public_html/profiles/commerce_kickstart/modules/contrib/entity/includes/entity.wrapper.inc).

Just thought I should chime in. I've run into this problem on multiple websites. Here's the full error.
EntityMetadataWrapperException: Unable to get the data property currency_code as the parent data structure is not set. in EntityStructureWrapper->getPropertyValue() (line 438 of /sites/all/modules/entity/includes/entity.wrapper.inc).

I've managed to work around this by removing the lines that throw this error as shown below:

diff --git a/includes/entity.wrapper.inc b/includes/entity.wrapper.inc
index 67764e7..8e02ea4 100644
--- a/includes/entity.wrapper.inc
+++ b/includes/entity.wrapper.inc
@@ -434,9 +434,6 @@ class EntityStructureWrapper extends EntityMetadataWrapper implements IteratorAg
   protected function getPropertyValue($name, &$info) {
     $options = array('language' => $this->getPropertyLanguage(), 'absolute' => TRUE);
     $data = $this->value();
-    if (!isset($data)) {
-      throw new EntityMetadataWrapperException('Unable to get the data property ' . check_plain($name) . ' as the parent data structure is not set.');
-    }
     return $info['getter callback']($data, $options, $name, $this->type, $info);
   }
 
@@ -447,9 +444,6 @@ class EntityStructureWrapper extends EntityMetadataWrapper implements IteratorAg
     if (!empty($info['raw getter callback'])) {
       $options = array('language' => $this->getPropertyLanguage(), 'absolute' => TRUE);
       $data = $this->value();
-      if (!isset($data)) {
-        throw new EntityMetadataWrapperException('Unable to get the data property ' . check_plain($name) . ' as the parent data structure is not set.');
-      }
       return $info['raw getter callback']($data, $options, $name, $this->type, $info);
     }
     return $this->getPropertyValue($name, $info);

It would be nice to have a permantent solution, but I'm not sure how to get to the bottom of where it's coming from.

Added a couple of issues I believe are related.

In my case, #3 will make the order bypass the coupons applied because it originally did not get the coupon data, that's why the entity module returned it did not get the parent data.

I can confirm that this is related to the coupon module in my case, it happens if you add a coupon to an order, then leave the review page and then return to the review page.

I also experience this error.
"past" module gives me a stack trace:

[%type] (string): EntityMetadataWrapperException
[!message] (string): Unable to get the data property currency_code as the parent data structure is not set.
[%function] (string): EntityStructureWrapper->getPropertyValue()
[%file] (string): sites/all/modules/contrib/entity/includes/entity.wrapper.inc
[%line] (string): 457
[%trace] (string):
 #0 sites/all/modules/contrib/entity/includes/entity.wrapper.inc(86): EntityStructureWrapper->getPropertyValue('currency_code', Array)
 #1 sites/all/modules/contrib/entity/includes/entity.wrapper.inc(273): EntityMetadataWrapper->value()
 #2 sites/all/modules/contrib/commerce/modules/line_item/commerce_line_item.module(1522): EntityValueWrapper->value()
 #3 sites/all/modules/contrib/commerce/modules/line_item/includes/views/handlers/commerce_line_item_handler_area_line_item_summary.inc(97): commerce_line_items_total(Array)
 #4 sites/all/modules/contrib/views/plugins/views_plugin_display.inc(2698): commerce_line_item_handler_area_line_item_summary->render(false)
 #5 sites/all/modules/contrib/views/theme/theme.inc(73): views_plugin_display->render_area(Object(commerce_line_item_handler_area_line_item_summary), false)
 #6 includes/theme.inc(1136): template_preprocess_views_view(Array, 'views_view')
 #7 sites/all/modules/contrib/views/plugins/views_plugin_display.inc(2692): theme('views_view', Array)
 #8 sites/all/modules/contrib/views/includes/view.inc(1264): views_plugin_display->render()
 #9 sites/all/modules/contrib/commerce/commerce.module(373): view->render()
#10 sites/all/modules/contrib/commerce/modules/cart/includes/commerce_cart.pages.inc(45): commerce_embed_view('commerce_cart_f...', 'default', Array, 'cart')
#11 includes/menu.inc(527): commerce_cart_view()
#12 index.php(21): menu_execute_active_handler()
#13 {main}
[severity_level] (string): 3

The culprit is this code in commerce_line_item.module:

function commerce_line_items_total($line_items, $types = array()) {
  [..]

  // Populate an array of how many line items on the order use each currency.
  foreach ($line_items as $delta => $line_item_wrapper) {
    // Convert the line item to a wrapper if necessary.
    if (!$line_item_wrapper instanceof EntityMetadataWrapper) {
      $line_item_wrapper = entity_metadata_wrapper('commerce_line_item', $line_item_wrapper);
    }

    $line_item_currency_code = $line_item_wrapper->commerce_total->currency_code->value();

In my case, I have a custom line item type where the commerce_total is empty, that is, it has no field items.

Solution

The question is: Do we consider such a line item "broken", or is this is a rare but valid case that needs to be supported?

Consider it "broken", and throw a custom exception.

Do not just let Entity API throw its exception.
Instead, either
- catch the exception from Entity API, and throw a custom exception, saying "Line item 123 of type xyz does not have any items in commerce_total field. Cannot compute order total from 5 line items.", or
- check whether commerce_total exists (e.g. !empty($line_item_wrapper->commerce_total->value()), and then throw a custom exception.

Consider it "broken", but treat it as price === zero

As above, either catch the EntityMetadataWrapperException, or do a check before.

Log a watchdog message, saying "line item 123 of type xyz does not have any items in commerce_total field. It was assumed that this item is for free.".

Then skip this line item for calculating the sum.

Consider it a valid case, treat as zero

As above: Either catch the EntityMetadataWrapperException, or do a check before.

Then simply count the item as zero / skip it, and do not log an error or throw an exception.

Notes

I want to say the entire function commerce_line_items_total() looks way more complicated than it should be.
Also, it looks like it will fail if the list is empty? Just a guess.

I found some code duplication:
- commerce_order_calculate_total()
- commerce_line_items_total()

These two share a lot of code, and are susceptible to the same error, if commerce_total has no field items for one line item.

The differences:
- commerce_order_calculate_total() also removes orphan line item references from the order.
- commerce_order_calculate_total() writes the result into $order_wrapper->commerce_order_total, instead of returning it.

It could be refactored such that commerce_order_calculate_total() would call commerce_line_items_total() for the calculation.

I found some code duplication:
- commerce_order_calculate_total()
- commerce_line_items_total()

Another difference:
commerce_order_calculate_total() also looks into the components for each $line_item_wrapper->commerce_total.
commerce_line_items_total() does not do this.
This is strange.
Shouldn't both give the same result?

I re-open this, because there is now more information.
If the questions in my previous posts can be answered, I can produce a patch, which fixes this issue and also cleans up the two functions.