Laravel Eloquent - Override Model's constructor to change attributes - php

Question

So I have a Page Model, which extends the Eloquent Model class. I am trying to override the constructor, where I need some additional logic. This is what I currently have:
class Page extends Model
{
public function __construct(array $attributes = [])
{
parent::__construct($attributes);
$this->main_image = null;
}
}
But this does not seem to save the main_image into the $this->attributes property when I call Page::find(1);.
I believe this is because Page::find eventually calls Model::newFromBuilder, which looks like this:
public function newFromBuilder($attributes = [], $connection = null)
{
$model = $this->newInstance([], true);
$model->setRawAttributes((array) $attributes, true);
$model->setConnection($connection ?: $this->getConnectionName());
return $model;
}
So as you can see it creates the instance first and then sets the attributes, which means that anything set in the constructor gets ignored.
Is there any workaround for this to be able to override constructor (or similar method) to change the attributes for every retrieved/created model instance? Obviously I could override the newFromBuilder, newInstance, __construct and similar methods, but this seems very hacky and unmaintainable.
Thanks!

Answer 1

If all you need is to be able automatically modify a model's attribute when retrieved or set, then use Laravel Eloquent's Accesors and Mutators:
Defining An Accessor
To define an accessor, create a getFooAttribute method on your model where Foo is the "studly" cased name of the column you wish to access. In this example, we'll define an accessor for the first_name attribute. The accessor will automatically be called by Eloquent when attempting to retrieve the value of the first_name attribute:
<?php
namespace App;
use Illuminate\Database\Eloquent\Model;
class User extends Model
{
/**
* Get the user's first name.
*
* #param string $value
* #return string
*/
public function getFirstNameAttribute($value)
{
return ucfirst($value);
}
}
As you can see, the original value of the column is passed to the accessor, allowing you to manipulate and return the value. To access the value of the accessor, you may simply access the first_name attribute on a model instance:
$user = App\User::find(1);
$firstName = $user->first_name;
Defining A Mutator
To define a mutator, define a setFooAttribute method on your model where Foo is the "studly" cased name of the column you wish to access. So, again, let's define a mutator for the first_name attribute. This mutator will be automatically called when we attempt to set the value of the first_name attribute on the model:
<?php
namespace App;
use Illuminate\Database\Eloquent\Model;
class User extends Model
{
/**
* Set the user's first name.
*
* #param string $value
* #return void
*/
public function setFirstNameAttribute($value)
{
$this->attributes['first_name'] = strtolower($value);
}
}
The mutator will receive the value that is being set on the attribute, allowing you to manipulate the value and set the manipulated value on the Eloquent model's internal $attributes property. So, for example, if we attempt to set the first_name attribute to Sally:
$user = App\User::find(1);
$user->first_name = 'Sally';
In this example, the setFirstNameAttribute function will be called with the value Sally. The mutator will then apply the strtolower function to the name and set its resulting value in the internal $attributes array.