I have a custom entity with a file field accepting multiple values. I would like to set file values according to https://www.drupal.org/docs/7/api/entity-api/entity-metadata-wrappers#example-value-set-save but none of the two methods are working here. I always get this error

error  php  Error: Call to a member function set() on null in include().

I am running Drupal 7, file_entity module enabled. Here follows the code:

$file = file_load(8172);
$wrapper = entity_metadata_wrapper('sys_ind', 13718);
$wrapper->field_allegati->file->set( $file );

2 Answers 2


Fixed! Thanks to this post Save a new value with entity_metadata_wrapper to an entity field which is an array

$file = file_load(8172);
$node = entity_load('sys_ind', array(13718));
$wrapper = entity_metadata_wrapper('sys_ind', '13718');

$wrapper->field_allegati[NULL]->file->set( $file ); # This worked


so the fix is using NULL (at least in multivalue field like mine is), not 0 or any other index nor [].


Try this to see if it works:

$wrapper->field_allegati[0] = (array) $file;

The wrapper seems to struggle with file fields

  • nope, just tried, error changes to EntityMetadataWrapperException: Invalid data value given. Be sure it matches the required data type and format. Value at [error] sys_ind(13718)->field_allegati: array ( 0 =>
    – rmorelli74
    Jan 10, 2019 at 15:47

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