How to load a taxonomy term (or entity) by field value?

Question

To load a taxonomy term programatically you can use EntityFieldQuery.

<?php

// Get taxonomy term by field value
$section_vocab = taxonomy_vocabulary_machine_name_load('section');

if($section_vocab) {
  $query = new EntityFieldQuery();
  $query->entityCondition('entity_type', 'taxonomy_term')
    ->propertyCondition('vid', $section_vocab->vid);
  $result = $query->execute();

  ...

}

However, that doesn't load the taxonomy term fields. Adding a field condition to the query$query->fieldCondition('field_id', 'value', '123'); to the query doesn't work as the result is always empty.

Bad solution

So the solution using EntityFieldQuery that I found here https://www.drupal.org/node/1517744 works, but it requires looping through all the terms in the vocabulary (in the worst case) which has a high cost.

<?php

// Get taxonomy term by field value
$section_vocab = taxonomy_vocabulary_machine_name_load('section');

$sectionID = NULL;

if($section_vocab) {
  $query = new EntityFieldQuery();
  $query->entityCondition('entity_type', 'taxonomy_term')
    ->propertyCondition('vid', $section_vocab->vid)
  $result = $query->execute();

  if (!empty($result['taxonomy_term'])) {
    // To load all terms.
    $terms = taxonomy_term_load_multiple(array_keys($result['taxonomy_term']));

    // Look up for the first term with the field value that we want.
    foreach ($terms as $term) {
      // Stop looking if we find it
      $value = $term->field_id['und'][0]['value'];
      if ($value == $IDtoFind){
        $termID = $term->tid;
        break;
      }
    }

  }
}

If the taxonomy term has a field with machine field_id, how can you load the taxonomy terms with a specific value for it?

Answer 1

As specified in the EntityFieldQuery documentation. It is not possible to query across multiple entity types. It is no possible to query all the terms with a specific field value as this would require querying both vocabulary->vid and field_id->value.

To load a taxonomy term by field value is possible to get all the entities that have that value:

  $query->entityCondition('entity_type', 'taxonomy_term')
    ->fieldCondition('field_id', 'value', $IDtoFind, '=');

Using ->fieldCondition('field_id', 'value', $IDtoFind, '=') and ->propertyCondition('vid', $section_vocab->vid) in the same query would produce an empty result.

Solution

For the code in the question this would work, based on that field_id is used only one vocabulary and it value is unique.

<?php
// Get taxonomy term by field value
$section_vocab = taxonomy_vocabulary_machine_name_load('section');

$sectionID = NULL;

if($section_vocab) {
  $query = new EntityFieldQuery();
  $query->entityCondition('entity_type', 'taxonomy_term')
    ->fieldCondition('field_id', 'value', $IDtoFind, '=');
  $result = $query->execute();

  if (!empty($result['taxonomy_term'])) {
    // Set the internal pointer of an array to its first element
    reset($result['taxonomy_term']);
    // Get the key value for the first item
    $termID = key($result['taxonomy_term']);

  }
}

Answer 2

You have to use https://api.drupal.org/api/drupal/modules%21taxonomy%21taxonomy.module/function/taxonomy_get_tree/7

In your case you have to set "load_entities" to TRUE

taxonomy_get_tree($vid, $parent = 0, $max_depth = NULL, $load_entities = FALSE);