Drupal API functions for working with taxonomy

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In Drupal API there are a number of useful features for taxonomy that provide nodes, classified on the definition terms, and let you know parent or child terms, etc.

Load the object of the term by its tid

Function taxonomy_term_load() by analogy with node_load() returns an object of the term by tid:

<?php
  $term = taxonomy_term_load(1);
  print $term->name; // the name of the term
  print $term->vid; // taxonomy vocabulary identifier to which the term belongs
?>

By analogy with node_load_multiple() in Drupal API there is a function taxonomy_term_load_multiple()

Find terms by name

To download terms by their names is a function taxonomy_get_term_by_name(), which returns an array of terms with the given name.

Get all vocabulary terms

To get all vocabulary terms with the hierarchy, you can use the taxonomy_get_tree(), where you want to pass a value vid – ID taxonomy vocabulary. In this case, the function returns objects with additional properties terms “depth” (the depth of the term in the hierarchy) and “parents” – an array of values tid parent terms. Sample code to display a “tree” vocabulary you will find on the page description of the function.

Gets the child terms

A fairly common task – to get the child terms specified term. For its solution is the function taxonomy_get_children(). Note that this function takes the tid of the term, and returns the full facilities of child terms (if any). That is not appropriate to use this feature, if we want, for example, only the values tid or name of child terms. In such situations, for performance reasons should write a request to the site database using db_select() (the basis of a request can be taken from the body of the function taxonomy_get_children()).

Gets the parent terms

For the parents given the term in the API Drupal 7 provides two functions – taxonomy_get_parents() and taxonomy_get_parents_all().

Despite nearly identical names, the functions differ substantially. The first return only “parents” specified term. Suppose we have a dictionary “Electronics”, it parental terms Sony and Panasonic, and the term “TV”, which is made as a child for Sony, as well as for Panasonic. Then the function call taxonomy_get_parents() by substituting into it the values tid of the term “TV” we get objects terms Sony and Panasonic.

The second function returns objects of “ancestors” of the term, and not only his parents, ie taking into account the entire depth of the vocabulary.

Load all the nodes of the term

For content classified by definition of the term, is a function taxonomy_select_nodes(). When all the evidence of her appointment beginners sometimes have problems associated with failure to take into account all the arguments of the function. So let’s look at an example. Suppose the term with tid = 1 is assigned 25 nodes. Then it is logical to assume that the line of code:

<?php
  $nids = taxonomy_select_nodes(1);
?>

returns an array of 25 elements – nid of nodes. However, it is not. Pay attention to the second argument, namely boolean variable $pager, the default to TRUE. This means that our sample will be divided by page. If we want to get all the nodes of the term on the same page, we need to convert the line of the code in:

<?php
  $nids = taxonomy_select_nodes(1, false);
?>

Also, when using the taxonomy_select_nodes(), you can set a limit on the number of loaded nodes and set the sort order by the parameters $limit and $order.

In conclusion, it is worth mentioning such useful features as taxonomy_get_vocabularies() – to download all the vocabularies taxonomy and its simplified version taxonomy_vocabulary_get_names(), which returns an array of objects, properties which are names, machine names and identifiers vid vocabularies.

This text is a translation of the article “Функции Drupal API для работы с таксономией” published by Sergey Belyaev on sergeybelyaev.name.

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