Drupal has a few ways how to get a value from an entity field.
And sometimes pro developers do it with wrong way. So, let's have a look for right way how to get field values.
<?php
use Drupal\node\Entity\Node;
$node = Node::load(123);
$field = $node->get('field_name');I guess, a lot of us use this way:
<?php
$value = $field->getValue();
dump($value);It returns an array with values and you have to do some extra manipulation with it like some loop and do some staff.
Well, the best way to get a single value from the field is:
<?php
$value = $field->getString();
dump($value);
This is a good approach to get a value for field type "Text" and it will return just a value of the field like a string.
Also, if you try use it for field type like "Reference" (node, taxonomy and etc.) it will return a string with IDs of the referenced entities like "1, 2, 3". But I don't recommend use it in case of field type "Reference".
Second case is a multiple fields. For some reasons we have to get the first value of multiple field.
<?php
$value = $field->first()->getString();
dump($value);And if you have to get second or third value of the value list you can use this one.
$value = $field->get(2)->getString();
dump($value);I believe, you will work with entities in you code and there is a way how get referenced entities.
<?php
$value = $field->referencedEntities();
dump($value);The code above returns an array with entities.
By the way, there is a helpful method to check if the value exist or not in the field:
dump($field->isEmpty());Basically, this is it. I hope you will use these approaches in you code.