Taxonomy is a very helpfull tool in Drupal's world.
However, support for "machine_name" is really missing, overall when you need to exchange terms with others systems.
In such situation, the only way is to create a field to hold external term code which is not the best way due to poor performance consequences.

This module create a new property named "machine_name" as for Taxonomy Vocabulary to store a "slug" for each term, and a "unique key" index to check unicity into a vocabulary.
If not provided during term creation, machine name will be automatically generated based on term name.

This new property can be used too with pathauto to generates rewrited urls.

Requirements

Taxonomy

Features

Alter database schema to add new column for "taxonomy_term_data" table
Automatically generate machine_name if missing based on term name
Can use Pathauto, Transliteration or Token to sluggify term name
Add function to load one term by its machine name
Machine name exposed to Views
Machine name exposed to Token
Machine name exposed to Migrate (Destination & Field Handler)
Machine name exposed to Rules

Note: working with Migrate, the reference is no more the 'name' property, but the 'machine_name'. So if you encountered duplicate names, that's because you have differente machine names.
For a such behavior, you have to use the "MigrateDestinationTermMachineName" destination class.

Installation and configuration

Put the module in sites/all/modules folder
Enable this module
If available, enable and setup Pathauto / Transliteration modules

Usage - Drupal 7.x

Load term by machine name

// Load with vid.
$vid = 1;
$term = taxonomy_term_machine_name_load('term_foo', $vid);
// Load with vocabulary machine name.
$vocabulary_machine_name = 'categories';
$term = taxonomy_term_machine_name_load('term_foo', $vocabulary_machine_name);
// Load with full object vocabulary.
$vocabulary = taxonomy_vocabulary_machine_name_load('categories');
$term = taxonomy_term_machine_name_load('term_foo', $vocabulary);

Migrate terms by machine name

CSV sample file

machine_name,name
term_1,Term 1
term_2,Term 2
term_3,Term 3
term_4,Term 4
term_5,Term 5
term_X1,Term X
term_X2,Term X
term_X3,Term X
term_X4,Term X
term_X5,Term X

Sample code

Notice: To support parent links between terms, you need to use MigrationTaxonomyTermMachineName as parent class instead of Migrate.

// Note the use of "MigrateDestinationTermMachineName" destination class.
class TestMigration extends MigrationTaxonomyTermMachineName {
  public function __construct(array $params) {
    parent::__construct();

    $this->description = t('Import');
    $this->machineName = 'example';

    // Create a map object for tracking the relationships between source rows
    $this->map = new MigrateSQLMap(
      $this->machineName,
      array(
        'machine_name' => array(
          'type'     => 'varchar',
          'length'   => 255,
          'not null' => TRUE,
        ),
      ),
      MigrateDestinationEntityAPI::getKeySchema('taxonomy_term')
    );

    // Create a MigrateSource object.
    $this->source      = new MigrateSourceCSV(
      drupal_get_path('module', 'migrate_example') . '/terms.csv',
      $this->columns(),
      array(
        'header_rows' => 1,
        'delimiter'   => ',',
      )
    );
    $this->destination = new MigrateDestinationTermMachineName('example');

    $this->addFieldMapping('machine_name', 'machine_name');
    $this->addFieldMapping('name', 'name');
  }

  /**
   * @return array
   */
  public function columns() {
    $columns   = array();
    $columns[] = array('machine_name', 'Machine name');
    $columns[] = array('name', 'Name');

    return $columns;
  }
}

Sample code (Migrate FIeld Handler)

// Use new property is available which switch mechanism to machine name instead of looking for taxonomy term using name.
$this->addFieldMapping('field_tags', 'tags');
$this->addFieldMapping('field_tags:machine_name')->defaultValue(TRUE);
// You can too enable the term creation based on machine name, which will fill the name with the machine name if term is not found.
$this->addFieldMapping('field_tags:create_term')->defaultValue(TRUE);

RTBC issues for Taxonomy Machine Name

Filters