How to write data to a custom field

Question

I had another question at Save data to custom field columns using entity_metadata_wrapper and a similar issue at https://drupal.org/node/2110161, which nobody has been able to figure out yet.

Since entity_metadata_wrapper isn't working for writing custom field values, how can I do this manually? I've tried the following code, but when I view the node afterwards, the field value is blank.

$fieldname = 'field_device_id';
    $query = db_insert('field_data_' . $fieldname)
        ->fields(array(
          'entity_type' => 'node',
          'bundle' => 'equipment',
          'entity_id' => $new_ent->getIdentifier(),
          'language' => 'und',
          'delta' => 0,
          $fieldname . '_esn_hex' => isset($conversion_values['ESN_HEX']) ? $conversion_values['ESN_HEX'] : NULL,
          $fieldname . '_esn_dec' => isset($conversion_values['ESN_DEC']) ? $conversion_values['ESN_DEC'] : NULL,
          $fieldname . '_meid_hex' => isset($conversion_values['MEID_HEX']) ? $conversion_values['MEID_HEX'] : NULL,
          $fieldname . '_meid_dec' => isset($conversion_values['MEID_DEC']) ? $conversion_values['MEID_DEC'] : NULL,
          $fieldname . '_imei_hex' => isset($conversion_values['IMEI_HEX']) ? $conversion_values['IMEI_HEX'] : NULL,
          $fieldname . '_imei_dec' => isset($conversion_values['IMEI_DEC']) ? $conversion_values['IMEI_DEC'] : NULL,
          $fieldname . '_iccid_hex' => isset($conversion_values['ICCID_HEX']) ? $conversion_values['ICCID_HEX'] : NULL,
          $fieldname . '_iccid_dec' => isset($conversion_values['ICCID_DEC']) ? $conversion_values['ICCID_DEC'] : NULL,
          $fieldname . '_raw_id' => $id,
        ))
        ->execute();
  }

This code runs after a submit handler passes in a device id that a user has entered, and converts it to several different formats, which are available in $conversion_values.

There has got to be a way to programmatically write values to custom field columns defined in hook_schema.

Answer 1

As far as the procedural method is concerned, you would use exactly the same method for a custom field as you would a contrib/core field.

Core field:

$node->body[LANGUAGE_NONE][0] = array(
  'value' = '<p>Some body text</p>',
  'format' => 'full_html',
);

Your custom field:

$node->field_whatever[LANGUAGE_NONE][0] = array(
  'esn_hex' => $some_val,
  'esn_dec' => $some_other_val,
  // etc...
);

To persist changes to both, use node_save() (or entity_save(), or whataver helper method the entity you're using provides).

node_save($node);

That's all you need to do. Manipulating the field tables manually is not recommended, as you bypass a lot of hooks that need to run, cache management, etc.

To use custom fields with an EntityMetadataWrapper, you need to go a bit further and describe the field and its columns to the entity module.

This involves adding property_type and property_callbacks to your field definition in hook_field_info(), and providing appropriate callbacks for those. There's a bit more information in this post