PHP's db class library Eloquent uses series (11) alone - adding model attributes

My Eloquent series of articles using
php's db class library Eloquent alone series (1)
php's db class library Eloquent alone series (2) - paging
php's db class library Eloquent alone series (3) - sql log
php db class library Eloquent used alone series (4) - event monitoring
php's db class library Eloquent used alone series (5) - model to array
php's db class library Eloquent used alone series (6) - one-to-one association with
php's db class Library Eloquent used alone series (7) - one-to-many association
php's db class library Eloquent used alone series (8) - many-to-many association
php's db class library Eloquent used alone series (9) - many-to-many association - table association
The db class library Eloquent of its own php uses the series (10) - many-to-many association - remote one-to-many
php db class library Eloquent uses the series (11) - many-to-many association - adding model attributes
php's db class library Eloquent Single use series (12) - result set model to array - 2




The purpose of this series of articles is to use Eloquent out of the laravel environment, because it is easy to use .
All codes in this series of articles have passed the test. Eloquent Version: 5.4.27

The purpose of this article is the extra properties of the model.
First create a table, assuming there is an active table act, each table has an area attribute area_id, which is associated with the area table, and the area table has a name field.

Now I want the activity model to have an area_name property automatically
then

Act.php

<?php
namespace app\model;
use \Illuminate\Database\Eloquent\Model;
/**
 * Active model class
 */
class Act extends Model
{
    protected $table = 'act';
    public $timestamps = false;
    
    protected $appends = ['area_name']; // add additional properties here
    protected $hidden = ['city']; //If not written like this, the city model will be added
    
    // custom properties
    // The name of this method is very particular, and the underscore is converted to camel case.
   // When getting attributes, use $act->area_name
    public function getAreaNameAttribute()
    {
        return $this->city->name; // The name property is in the city table.
    }
    
    // This is the general definition, since a city will have multiple events associated with it    
    public function city()  
    {  
        return $this->belongsTo('app\model\Area', 'area_id', 'id');  
    }  
}

client code

$act  = \app\model\Act:find(1);
echo $act->area_name;