How to get the Parent id from term id in drupal 8?

It's easy way to tackle this problem, Sometimes we face this issue and take the query help and get the parent id, but we have here solution for this issue.

Just write the loadParent syntax as per given instructions:

Syntax:

$term_id = $node->get('field_category')->target_id;

$term = \Drupal::entityTypeManager()->getStorage('taxonomy_term')->load($term_id);

$parentids = $term->parent->target_id;

OR

 $parent = \Drupal::entityTypeManager()->getStorage('taxonomy_term')->loadParents($term_id);   // here term_id is child term id
 $parent = reset($parent); //reset the parent array
 $parentids = $parent->id();    //get the parent id  


Note: If have any suggestions or issue regarding 'How to get the Parent id from term id in drupal 8?' then you can ask by comments.

Vocabulary or Taxonomy load in Drupal 8.

If we have vocabulary/taxonomy name then we can easily load by loadTree, follow the syntax.

$tree = \Drupal::entityTypeManager()->getStorage('taxonomy_term')->loadTree('write vocabulary machine name here');
foreach ($tree as $term) {
  echo $term->tid.' - '.$term->name;
}

Example:
$select_category .= '<select><option value="0">- Select -</option>';
$tree = \Drupal::entityTypeManager()->getStorage('taxonomy_term')->loadTree('product_family'); //here product_family is machine name of Product Family taxonomy.
foreach ($tree as $term) {
$select_category .= '<option value="' . $parent . '_' . $term->tid . '">' . $term->name . '</option>';
}
$select_category .= '</select>';


Note: If have any suggestions or issue regarding 'Vocabulary or Taxonomy load in Drupal 8.' then you can ask by comments.

How to render fields on Taxonomy twig templates?

It is easy to call/render taxonomy fields on taxonomy template. We just have to create template file according to vocabulary machine name like 'application landing page' is taxonomy and machine name will be 'application_landing_page', but our template name will be 'taxonomy-term--application-landing-page.html.twig' as per Drupal 8(Symphony) Syntax.

and we will call/render fields like..


Term id: {{ term.id }}  // term id

Term Url: {{ url }}  // current page url

Term Title: {{ term.label }}  // term title

Term Image: {{ file_url(term.field_product_group_image.entity.uri.value) }}  // show url of product group image is the image field in taxonomy

Term Description/body: {{ content.description }}

Term Link field: {{ term.field_link.0.url }}

Term Link Title field: {{ term.field_link.0.title }}

Term custom field: {{ content.field_machine_name }}


If we want to check any field value exist or not then we are giving an example like we have field 'line of business' so machine name will be line_of_busines and we will check by..

{% if content.field_line_of_busines is not empty %}

{{ content.field_line_of_busines }}

{% endif %}



Note: If have any suggestions or issue regarding 'How to render fields on Taxonomy twig templates' then you can ask by comments.

Taxonomy terms load in drupal 8.

In drupal 7, we have taxonomy_term_load($tid), taxonomy_term_load_multiple($tids) functions for load the taxonomy term or multiple terms but now in drupal 8 syntax is changed and now Single/Multiple term load by Term::load($tid)
or
Add the name space at the top of the page.
\Drupal\taxonomy\Entity\Term::load($tid);

If we are using Symfony library and calling name space 
use Drupal\taxonomy\Entity\Term;
use Drupal\taxonomy;

or direct use in function calling time like  \Drupal\taxonomy\Entity\Term::load($tid);

Example:
$term_detail_array = \Drupal\taxonomy\Entity\Term::load($tid);
or
$term_detail_array = Term::load($tid); //if we are already using taxonomy library..

Then get the fields detail by $term_detail_array like,

Term id:  $term_detail_array ->tid->value;
Term name:  $term_detail_array ->name->value;
Term manually added field:  $term_detail_array ->get('field_machine_name')->value;  // manually added field value..
Term image field:  $term_detail_array ->field_machine_name->entity->getFileUri();

 If we have field with entity reference then field value will be in form of $term_detail_array ->get('field_machine_name')->target_id;
or
If we have field without entity reference then field value will be in form of $term_detail_array ->get('field_machine_name')->value;

Now we will discuss on Term::loadMultiple.
And the syntax is $terms = \Drupal\taxonomy\Entity\Term::loadMultiple($tids); // here $tids is the array of multiple tid..
$terms = \Drupal\taxonomy\Entity\Term::loadMultiple($tids); 
foreach ($terms as $term) {  //then the fields value will be..
$term_id = $term->tid->value;
$term_name = $term->name->value;
$term_file field = $term->field_machine_name->uri;
}
and so on..

Note: If have any suggestions or issue regarding 'Taxonomy terms load in drupal 8' then you can ask by comments.