Calculate remaining days until birthday

Constantin Druc · 08 Mar, 2022

Here I have an Event model. You can think of it as being something like a birthday, wedding anniversary, things like that. The event has a date attribute, and we need to use this date to determine the next anniversary, the next date we celebrate the event.

 1<?php
 2 
 3namespace App\Models;
 4 
 5use Illuminate\Database\Eloquent\Factories\HasFactory;
 6use Illuminate\Database\Eloquent\Model;
 7 
 8class Event extends Model
 9{
10    use HasFactory;
11 
12    protected $guarded = [];
13    protected $dates = ['date'];
14}

Let's look at an axis representing time:

Today is 08-03-2022. If we are to get the next anniversary for a date, let’s say 01-06-1991, what we’d need to do is to bring that date to the current year.

However, some dates might still end up in the past. For example, 01-03-1991 will turn into 01-03-2022, which is in the past compared to our current 08-03-2022 date.

So if the normalized date is still in the past, we need to add one more year to it.

Here’s the accessor:

 1<?php
 2 
 3namespace App\Models;
 4 
 5use Illuminate\Database\Eloquent\Factories\HasFactory;
 6use Illuminate\Database\Eloquent\Model;
 7 
 8class Event extends Model
 9{
10    use HasFactory;
11 
12    protected $guarded = [];
13    protected $dates = ['date'];
14 
15    public function getNextAnniversaryAttribute() 
16    {
17        $date = $this->date;
18        $date->setYear(now()->year);
19 
20        if ($date->isPast()) {
21            $date->addYear();
22        }
23 
24        return $date;
25    }
26}

Since the next anniversary is a carbon date, we can get the remaining time in different formats. So we can do: diffInDays(), diffInMonths(), diffInYears(), and more.

One particular nice format is the diffForHumans() - this will give you the remaining time in a nice, readable format like: “11 months from now” or “8 days from now”.

Testing the next anniversary date

We can test the accessor by creating two events: one with a date that, when normalized, will end up in the past compared to our current date, and another one that will end up in the future.

 1<?php
 2 
 3namespace Tests\Feature\Models;
 4 
 5use App\Models\Event;
 6use Carbon\Carbon;
 7use Tests\TestCase;
 8 
 9class EventTest extends TestCase
10{
11    /** @test */
12    public function get_next_anniversary()
13    {
14        $eventA = new Event([
15            'date' => '01-03-1991'
16        ]);
17 
18        $this->assertTrue($eventA->next_anniversary->is('01-03-2023'));
19 
20        $eventB = new Event([
21            'date' => '01-06-1991'
22        ]);
23 
24        $this->assertTrue($eventB->next_anniversary->is('01-06-2022'));
25    }
26}

One thing to keep in mind when testing dates is that it’s a good idea to control whatever date is used as the current date; otherwise, the test will break at some point in the future.

To set the current date, we can use Carbon::setTestNow() and pass it the date in string format.

 1<?php
 2 
 3namespace Tests\Feature\Models;
 4 
 5use App\Models\Event;
 6use Carbon\Carbon;
 7use Tests\TestCase;
 8 
 9class EventTest extends TestCase
10{
11    /** @test */
12    public function get_next_anniversary()
13    {
14        Carbon::setTestNow('08-03-2022'); [tl! highlight]
15 
16        $eventA = new Event([
17            'date' => '01-03-1991'
18        ]);
19 
20        $this->assertTrue($eventA->next_anniversary->is('01-03-2023'));
21 
22        $eventB = new Event([
23            'date' => '01-06-1991'
24        ]);
25 
26        $this->assertTrue($eventB->next_anniversary->is('01-06-2022'));
27    }
28}

Defining accessors in Laravel 9

My favorite part is that we can remove the prefix and suffix and that both the accessor and the mutator are defined in the same place, under the same method.

 1<?php
 2 
 3namespace App\Models;
 4 
 5use Illuminate\Database\Eloquent\Casts\Attribute;
 6use Illuminate\Database\Eloquent\Factories\HasFactory;
 7use Illuminate\Database\Eloquent\Model;
 8 
 9class Event extends Model
10{
11    use HasFactory;
12 
13    protected $guarded = [];
14    protected $dates = ['date'];
15 
16    public function nextAnniversary(): Attribute
17    {
18        return Attribute::make(
19            get: function () {
20                $date = $this->date;
21                $date->setYear(now()->year);
22 
23                if ($date->isPast()) {
24                    $date->addYear();
25                }
26 
27                return $date;
28            }
29        );
30    }
31}

Calculate remaining days until birthday

Testing the next anniversary date

Defining accessors in Laravel 9

Laravel misc

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