Need a list of terms from a vocabulary machine name

Question

How can I get the terms of a vocabulary using vocabulary machine name.

I have used the following code, although it works for me but I am looking for efficient methods.

$vocabulary = taxonomy_vocabulary_machine_name_load('school_courses');
$terms = taxonomy_get_tree($vocabulary->vid);
$courses = array();
foreach($terms as $term) {
    $courses[$term->tid] = $term->name;
}

Answer 1

What you are doing is pretty much the same as Drupal core is doing for the term reference field, so doubt you can improve the code much.

/**
 * Returns the set of valid terms for a taxonomy field.
 *
 * @param $field
 *   The field definition.
 * @return
 *   The array of valid terms for this field, keyed by term id.
 */
function taxonomy_allowed_values($field) {
  $options = array();
  foreach ($field['settings']['allowed_values'] as $tree) {
    if ($vocabulary = taxonomy_vocabulary_machine_name_load($tree['vocabulary'])) {
      if ($terms = taxonomy_get_tree($vocabulary->vid, $tree['parent'])) {
        foreach ($terms as $term) {
          $options[$term->tid] = str_repeat('-', $term->depth) . $term->name;
        }
      }
    }
  }
  return $options;
}

Answer 2

Using EntityFieldQuery, you can add

->entityCondition('bundle', 'my_machine_name') to get terms by vocabulary name:

Example:

$query = new EntityFieldQuery();
$result = $query->entityCondition('entity_type', 'taxonomy_term')
                ->entityCondition('bundle', 'my_machine_name')
                ->execute();

Answer 3

I use EntityFieldQuery:

// Get vid from machine_name
$my_vocabulary = taxonomy_vocabulary_machine_name_load('my_machine_name');
$my_vid = $my_vocabulary->vid;

// Build and execute the query 
$query = new EntityFieldQuery();
$query->entityCondition('entity_type', 'taxonomy_term')
    ->propertyCondition('vid', $my_vid)
$result = $query->execute();

// Process the result
var_dump($result);

Output:

array(1) {
  ["taxonomy_term"]=>
  array(8) {
    [12]=>
    object(stdClass)#145 (1) {
      ["tid"]=>
      string(2) "12"
    }
    [14]=>
    object(stdClass)#149 (1) {
      ["tid"]=>
      string(2) "14"
    }
    /* etc... */
  }
}

http://api.drupal.org/api/drupal/includes!entity.inc/class/EntityFieldQuery/7