EntityMetadataWrapperException: unknown data property for field

Question

I have recently been trying to update my code to use entity wrappers to access field values. Now I have this:

$wrapper = entity_metadata_wrapper("node", $nid);
print($wrapper->field_property_sample()->value());

instead of this:

print($node->field_property_sample[LANGUAGE_NONE][0]["value"]);

The problem is sometimes I encounter this:

EntityMetadataWrapperException: unknown data property field_property_sample.

Is there a way for me to workaround this?

I have about 10 of these fields that can throw this exception and it is really getting ugly

$wrapper = entity_metadata_wrapper("node", $nid);

try {
  print($wrapper->field_property_sample()->value());
} catch (EntityMetadataWrapperException &e){
  print("");
}

/** repeat 10 times **/

Is there some function that I can more or less call like this?

$wrapper = entity_metadata_wrapper("node", $nid);
print($wrapper->field_property_sample->exists() ? $wrapper->field_property_sample->value()  : "" );

/** repeat 10 times **/

Answer 1

Yep, you can just use existing features of the PHP language

try {
  print($wrapper->field_property_sample->value());
}
catch (EntityMetadataWrapperException $e) {
  // Recover
}

Or, since EntityMetadataWrapper implements __isset() you can use that:

print isset($wrapper->field_property_sample) ? $wrapper->field_property_sample->value() : '';

Answer 2

With reference to Clive's answer, you can use __isset() like this:

print ($wrapper->__isset('field_property_sample') ? $wrapper->field_property_sample->value() : '';

Answer 3

On nested field collections:

When iterating over a list of field collections, and checking for a non-empty field collection nested within the first, isset() does not work. However, I found that checking:

  foreach ($node_wrapper->field_fc_one AS $field_collection) {

    // Grab a nested field collection, properly wrapped.
    $nested_fc_wrapper = $field_collection->field_nested_fc;

    // isset() or $wrapper->__isset('') do not work here, but this does:
    if(nested_fc_wrapper->getIdentifier()) {

      // Do some stuff
    }
  }

Answer 4

Using field_property_sample() doesn't make sense, because:

• $wrapper->field_property_sample() is used to call a class method
• $wrapper->field_property_sample is used to get a value of the class property

Property is the variable which you want to use, class method is the function which you want to call.

So using:

$wrapper->field_property_sample->value();

is the correct syntax.

For proper usage of Entity metadata wrappers, check: Entity metadata wrappers page.

Here is some code example:

try {
  $wrapper = entity_metadata_wrapper('node', $node);
  $wrapper->field_property_sample = 'some data';
  $wrapper->field_multi_sample = array('1st', '2nd');
  $wrapper->save();
}
catch (EntityMetadataWrapperException $e) {
  watchdog_exception('my_module', $e);
}

To print, use:

print($wrapper->field_property_sample->value());

or dpm(), dd() from Devel module.