Following [yesterday's Entity Metadata Wrapper blog post](/blog/cleanly-retrieving-user-profile-data-using-entity-metadata-wrapper) and as I continued to work on this task, I noticed some duplication and found that I was repeating several of the same chaining steps in different methods in the same file. For example:
```php
public function getFirstName(): string {
return $this
->get('profile_user_basic') // Get the pupil's profile.
->get('field_first_name')
->value();
}
private function getTeacherFirstName(): string {
$this
->get('profile_student') // Get the pupil's profile.
->get('field_class') // Get the pupil's class.
->get('field_teacher') // Get the class' teacher.
->get('profile_user_basic') // Get the teacher's profile.
->get('field_first_name')
->value();
}
```
In both cases, the last three lines are the same, where the same profile type is loaded, and the value is loaded from a field.
I wanted to find a way to remove this duplication whilst also making the code more readable. Ideally, this would mean adding a method like `getFirstNameFromBasicProfile()` that would group the last three steps.
## Extending the EntityDrupalWrapper
I've done this before, where I've created a custom wrapper class with its own methods and extends `EntityDrupalWrapper`. This is how that might look:
```php
final class PupilWrapper extends \EntityDrupalWrapper {
public function __construct(\stdClass $data, $info = []) {
parent::__construct('user', $data, $info);
}
public function getFirstName(): string {
return $this->getFirstNameFromBasicProfile();
}
public function getTeacherFirstName(): string {
return $this
->get('profile_student')
->get('field_class')
->get('field_teacher')
->getFirstNameFromBasicProfile();
}
private function getFirstNameFromBasicProfile(): string {
return $this
->get('profile_user_basic')
->get('field_first_name')
->value();
}
}
```
Whilst this has worked in previous situations, this time I had this error:
> Error: Call to undefined method EntityDrupalWrapper::getFirstNameFromBasicProfile() in Drupal\my_module\EntityWrapper\PupilWrapper->getTeacherFirstName
This is because the `get()` method is returning an instance of `EntityStructureWrapper` (another class that extends `EntityDrupalWrapper`) which means that `getFirstNameFromBasicProfile()` is not accessible though it's in the same file.
I tried overridding the `get()` method but wasn't able to get this to work.
## Decorating the EntityDrupalWrapper
Another option that I tried was to follow the Decorator design pattern, and add a new class that takes an `EntityDrupalWrapper` as an argument as uses it internally but doesn't extend it. Here's an example:
```php
final class PupilWrapper {
private $accountWrapper;
public function __construct(\EntityMetadataWrapper $accountWrapper) {
$this->accountWrapper = $accountWrapper;
}
public function getFirstName(): string {
return $this->getFirstNameFromBasicProfile();
}
public function getTeacherFirstName(): string {
return $this
->get('profile_student')
->get('field_class')
->get('field_teacher')
->getFirstNameFromBasicProfile();
}
private function getFirstNameFromBasicProfile(): string {
return $this
->get('profile_user_basic')
->get('field_first_name')
->value();
}
}
```
In this case, the constructor argument is an instance of `EntityMetadataWrapper` so that it could be either an `EntityDrupalWrapper` or `EntityStructureWrapper`.
### Re-adding required wrapper methods
As the `get()` method is missing, this would cause an error:
> Error: Call to undefined method Drupal\my_module\EntityWrapper\PupilWrapper::get() in Drupal\my_module\EntityWrapper\PupilWrapper->getFirstName()
However, we can re-add it, have it get the value from `accountWrapper` and return another instance of `PupilWrapper` so that `getFirstNameFromBasicProfile()` will be available.
```php
public function get(string $property): self {
return new self($this->accountWrapper->get($property));
}
```
The `value()` method is also required, but this can delegate to the decorated wrapper:
> Error: Call to undefined method Drupal\my_module\EntityWrapper\PupilWrapper::value() in Drupal\my_module\EntityWrapper\PupilWrapper->getFirstName()
```php
public function value(): string {
return $this->accountWrapper->value();
}
```
## Conclusion
This was the first time that I tried extending Drupal 7's entity metadata wrappers in this way, but it worked well, removes the duplication and cleans up the code further.
