Drupal 8 Entity API cheat sheet

if you've already read the official Drupal 8 Entity API documentation and you want more examples, here's a handy cheat sheet:

The examples here contain some hard-coded IDs. These are all examples. In your real code, you should already have the node IDs, file IDs, etc. in a variable.

Working with nodes

Load a node by NID:

$nid = 123; // example value
$node_storage = \Drupal::entityTypeManager()->getStorage('node');
$node = $node_storage->load($nid);

Get node's NID:

echo $node->id(); // 123

Get node's bundle type:

echo $node->bundle(); // 'article'
echo $node->getType(); // 'article' - this is the same as bundle() for most entities, but doesn't work for all entity types

Get a built-in field value:

echo $node->get('title')->value; // "Lorem Ipsum..."
echo $node->get('created')->value; // 1510948801
echo $node->get('body')->value; // "The full node body, <strong>with HTML</strong>"
echo $node->get('body')->summary; // "This is the summary"
// a custom text field
echo $node->get('field_foo')->value; // "whatever is in your custom field"
// a file field
echo $node->get('field_image')->target_id; // 432 (a managed file FID)

or the shorthand, with magic getters:

echo $node->title->value; // "Lorem Ipsum..."
echo $node->created->value; // 1510948801
echo $node->body->value; // "This is the full node body, <strong>with HTML</strong>"
echo $node->body->summary; // "This is the summary"
echo $node->field_foo->value; // "whatever is in your custom field"
echo $node->field_image->target_id; // 432

For more about that file entity target ID, see the "Working with File Entities" section below

Get nodes from a query:

$query = \Drupal::entityQuery('node')
->condition('type', 'article'),
->condition('field_foo', 42);
$nids = $query->execute();
$nodes = $node_storage->loadMultiple($nids);

 
foreach ($nodes as $n) {
echo $n->title->value; // "Lorem Ipsum..."
 
// do whatever you would do with a node object (set fields, save, etc.)
$n->set('title', "this is a test");
$n->save();
}

Set fields

$node->set('title', "Moby Dick");
$node->set('body', array(
'summary' => "Book about a whale",
'value' => "Call me Ishmael...",
'format' => 'basic_html',
));
$node->save();

Delete node(s)

// one

$nid = 42; // example value
$node = $node_storage->load($nid);
$node->delete();

// multiple

$nids = [21,12,45,67]; // example value
$nodes = $node_storage->loadMultiple($nids);
$node_storage->delete($nodes); 

// multiple, loading one at a time to avoid "out of memory" errors - may be slow

$nids = [21,12,45,67]; // example value
foreach($nids as $nid)
{
$node = $node_storage->load($nid);
$node->delete();
}

Working with Paragraphs

"Paragraphs" (from the popular contrib module of the same name) are separate entities that are related to the parent nodes via an entity reference revision.

$my_paragraph = null;
 
foreach ($node->get('field_paragraph_reference') as $para) {
if ($para->entity->getType() == 'your_paragraph_type') { // e.g., "main_content" or "social_media"
$my_paragraph = $para->entity;
}
}

if (!empty($my_paragraph)) {
// $my_paragraph is a regular entity and can be interacted with like any other entity
echo $my_paragraph->field_somefield->value;
 
// (however, they don't have a "title" like a node)
echo $my_paragraph->title->value; // <-- this won't work
} else {
echo "The node doesn't have this paragraph type.";
}

Get paragraph entity type:

echo $my_paragraph->getType(); // "main_content"

Working with File entities
Managed files are also separate entities, which are associated with the node using a type of Entity Reference.

Get a file by ID:

$fid = 42; // example value
$file_storage = \Drupal::entityTypeManager()->getStorage('file');
$file = $file_storage->load($fid);

Get a file referenced in a node:

$file = $node->field_image->entity;
Reading some properties from a File entity:

echo $file->getFileUri(); // "public://file123.jpg"
// if you want the URL without Drupal's custom scheme, you can translate it to a plain URL:
echo file_url_transform_relative(file_create_url($file->getFileUri())); // "/sites/default/files/public/file123.jpg"
echo $file->filename->value; // "file123.jpg"
echo $file->filemime->value; // "image/jpeg"
echo $file->filesize->value; // 63518 (size in bytes)
echo $file->created->value; // 1511206249 (Unix timestamp)
echo $file->changed->value; // 1511234256 (Unix timestamp)
echo $file->id(); // 432

To see what other properties are available, look at the columns in the `file_managed` table.

The file's user data

echo $file->uid->target_id; // 1
echo $file->uid->value; // <-- doesn't work. Use target_id instead.
echo $file->uid->entity->name->value; // "alice"
echo $file->uid->entity->timezone->value; // "America/Los_Angeles"

Working with Entity References
Reading from entity reference fields that allow multiple values:

foreach ($node->field_my_entity_reference as $reference) {
 
// if you chose "Entity ID" as the display mode for the entity reference field,
// the target_id is the ONLY value you will have access to
echo $reference->target_id; // 1 (a node's nid)
 
// if you chose "Rendered Entity" as the display mode, you'll be able to
// access the rest of the node's data.
echo $reference->entity->title->value; // "Moby Dick"
 
}

Populate the value of an entity reference field which allows multiple values (this replaces any existing value in the DB)

$nids = [3,4,5,6]; // example value
$node->set('field_my_entity_reference', $nids);
$node->save();
Append new referenced items to an entity reference field (this preserves existing values)

$nids = [3,4,5,6]; // example value
foreach ($nids as $nid) {
$node->field_my_entity_reference[] = [
'target_id' => $nid
];
}
$node->save();

Working with group

built-in field value

$targetId = $group->get('group_roles')->target_id; // "partner-manager"

or the shorthand, with magic getters:

$targetId = $group->group_roles->target_id; //"partner-manager"

I hope this saves everyone some time. It certainly is helpful to me every time I write a custom Drupal 8 module.

Happy coding!