I understand that I can append values to an entity reference field to a node normally with this method

$node->field_tags[] = [
    'target_id' => $my_id,

However I have a function like so

function addTag($node,$field,$id){
    'target_id' => $id,

In other words I have to anticipate any field the user supplies. Looking at the node class here


I did discover the set function that lets me specify a field and a value but I don't believe that this would append to an array of entities in a field.

How would I append to an entity reference field to a node if the field name is supplied in a variable?

  • 2
    You could just use variable variables: $node->{$field}[] = ..., but I wouldn’t be surprised if the API offered something more pleasing
    – Clive
    Commented Nov 8, 2017 at 19:08

1 Answer 1


Yes, the class Node is a good starting point to look for an OOP way:

Click on get(), which returns a field object FieldItemList, where you can use the method appendItem():

  'target_id' => $id,

Replace ->get() with {} and ->appendItem() with [] and you get the shorter version which @Clive mentioned in the comment:

$node->{$field}[] = $id;

This is possible because of the magic method ContentEntityBase::__get and the ArrayAccess interface the field implements. I've also dropped target_id, because you don't need this for the main property of a field.

  • 1
    Great that worked! What's better practice? The oop way or the other?
    – Amy
    Commented Nov 9, 2017 at 16:27
  • 1
    You can't go wrong by using OOP. But I've seen both and all possible combination in between.
    – 4uk4
    Commented Nov 9, 2017 at 16:40

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