Updating fields programmatically is a core task for any Drupal developer, whether you are building custom migrations, syncing data from external APIs, or automating content workflows. If you are coming from a Drupal 7 background, you likely remember the complex nested arrays required to target specific language keys and deltas.

In modern Drupal (versions 8, 9, 10, and 11), the Entity API has been significantly streamlined. However, managing entity reference fields—which link nodes to users, taxonomy terms, or other entities—still requires a specific understanding of how properties like target_id and entity work. In this guide, you will learn the most efficient ways to update these fields programmatically.

Understanding the target_id Property

The most common way to update an entity reference field is by manipulating its target_id. This is the primary property stored in the database. When you want to link a node to a specific user or another content item, you simply need the ID of that target entity.

To update a single-value field, you can use the following syntax:

use Drupal\node\Entity\Node;

// Load the node you want to update.
$node = Node::load($nid);

// Set the target_id directly.
$node->field_code_used_by->target_id = $user_id;

// Save the entity to persist changes.
$node->save();

Because target_id is the main property of an entity reference field, Drupal allows a shorthand. You can often omit the property name entirely when setting a single value:

$node->field_code_used_by = $user_id;

Updating Fields Using Entity Objects

Sometimes you may already have the entity object (e.g., a User or Term object) available in your code. Instead of manually extracting the ID, you can assign the object directly to the entity property.

This is a "computed" property. When you assign an object here, Drupal automatically identifies the ID and prepares it for storage. This approach is often more readable and less error-prone than passing around raw integers.

use Drupal\node\Entity\Node;
use Drupal\user\Entity\User;

$node = Node::load($nid);
$user = User::load(1);

// Assign the entity object directly.
$node->field_code_used_by->entity = $user;
$node->save();

Managing Multi-Value Entity Reference Fields

Handling fields that allow multiple values requires a different strategy. If you use the assignment method (=) on a multi-value field, you will overwrite all existing values. To add new references without deleting old ones, you have several options.

The Array Shorthand

To add a new item to the end of a list, you can use the empty bracket syntax common in PHP arrays:

$node->field_code_used_by[] = ['target_id' => $user_id];

Using the appendItem Method

For a more explicit and object-oriented approach, use the appendItem() method. This is particularly useful when looping through a collection of IDs:

$imageIds = ['3', '32', '50'];

foreach ($imageIds as $fid) {
  $node->get('field_article_images')->appendItem([
    'target_id' => $fid,
  ]);
}
$node->save();

Overwriting with a New Set

If you need to replace the entire list of references with a specific array of IDs, use the set() method:

$multi_value = [
  ['target_id' => 101],
  ['target_id' => 102],
];
$node->set('field_NAME', $multi_value);
$node->save();

Best Practices for Entity Updates

When programmatically updating entities, keep these three rules in mind to ensure performance and data integrity:

  1. Always Call save(): Changes made to an entity object exist only in memory until you call $node->save().
  2. Check for Existence: Before calling methods on a loaded entity, ensure the entity actually exists to avoid "call to a member function on null" errors.
  3. Use Dependency Injection: While Node::load() is convenient for quick scripts, always use dependency injection for the entity_type.manager service when writing custom modules or controllers.

Frequently Asked Questions

Can I use these methods for Taxonomy Terms?

Yes. Taxonomy terms are entities. To update a term reference field, you simply use the term's ID as the target_id. The logic remains identical to node or user references.

Why is my field not updating in the database?

Double-check that you are calling the save() method on the parent entity. Additionally, ensure that the user or process running the code has the necessary permissions to update the entity, though programmatic saves typically bypass UI-level permission checks.

How do I clear an entity reference field?

To completely remove all values from a field, you can set it to an empty array or null: $node->set('field_name', []); or $node->field_name = NULL; followed by $node->save();.

Wrapping Up

Programmatically updating entity reference fields in modern Drupal is highly flexible. Whether you prefer the directness of target_id, the readability of assigning an entity object, or the precision of appendItem(), the Entity API provides the tools you need. By mastering these patterns, you can write cleaner, more maintainable code for your Drupal applications.