Is $post->comments()->create() more expensive than Comment::create() in Laravel? - php

Question

In Laravel PHP Framework, when you have, let's say, a relationship between two tables e.g. one post can have one or multiple comments, you can create the comments of the post these ways:
// Option 1
$post->comments()->create(['text' => 'Greate article...']);
or
// Option 2
Comment::create([
'post_id' => 1,
'text' => 'Greate article...',
]);
Of course, it depends on the cases. Below are my cases.
For both options, the Post ID 1 has already been validated in the form request whether the post with the ID 1 does exist or not.
For some reasons, I already need to retrieve the post from the database first, thus I already have the post model.
In these above cases, is the Option 1 more expensive than the Option 2?

Answer 1

You can test the queries your application makes by listening to the queries using DB::listen().
I have setup the following as a test:
Migrations:
Schema::create('posts', function (Blueprint $table) {
$table->bigIncrements('id');
$table->string('title');
$table->string('content');
$table->timestamps();
});
Schema::create('comments', function (Blueprint $table) {
$table->bigIncrements('id');
$table->unsignedBigInteger('post_id');
$table->string('text');
$table->timestamps();
});
Models:
class Post extends Model
{
protected $guarded = [];
public function comments()
{
return $this->hasMany(Comment::class);
}
}
class Comment extends Model
{
protected $guarded = [];
public function post()
{
return $this->belongsTo(Post::class);
}
}
Test:
$post = Post::create([
'title' => 'Hello World',
'content' => 'Here I am!',
]);
$queries = collect();
DB::listen(function ($query) use ($queries) {
$queries->push($query->time);
});
for ($i = 1; $i <= 3000; $i += 1) {
Comment::create([
'post_id' => $post->id,
'text' => 'Facade '.$i,
]);
$post->comments()->create([
'text' => 'Relation '.$i,
]);
}
$totalTime = [0, 0];
foreach ($queries as $idx => $time) {
$totalTime[$idx%2] += $time;
}
return [
'facade' => $totalTime[0],
'relation' => $totalTime[1],
];
This outputs:
array:2 [▼
"facade" => 1861.3
"relation" => 1919.9
]
So you can see the relation way of create is actually approximately 3% slower in my test scenario.
I have prepared this implode if you want to experiment further.

Answer 2

If it is "cheaper", it won't be by a noticeable amount. You're creating an instance of a Query builder, but you're not actually querying anything. So in this case it's only adding the post_id on the new model you're creating.
I don't think it's something you worry about too much.