hasMany. Possible to avoid select in foreach?

It is hard to tell what you mean without showing code, but this might help? https://laravel.com/docs/master/eloquent-relationships#eager-loading

It looks like this is the way Laravel works.

If a record is not saved, the hasMany seems smart enough to not query the database. What I am looking to do is have it not do things I have not asked for. I would like to preserve the behaviour of an unsaved record.

In Artisan Tinker:

Setup:

// Log all SQL queries (don't commit this, you'll only want to do it locally
DB::listen(function($query) {
    Log::info(
        $query->sql,
        $query->bindings,
        $query->time
    );
});

Firstly, what happens when a Post is not saved

it's a blank Model with primary key, timestamps

// We create a non-persistent Model
$post = new App\Models\Post();
// This makes no query. It works with the in-memory collection. It's result is 0.
$post->revisions->count();
// This makes a database query. It ignores the local in-memory collection. It's result is 0.
$post->revisions()->count();

// create 10 revisions
foreach(range(1, 10) as $number) {
    $revision = new \App\Models\PostRevision();
    $revision->post_id = $post->id;
    $post->revisions[] = $revision;
}

// This makes no query. It works with the in-memory collection. It's result is 10.
$post->revisions->count();
// This makes a database query. It ignores the local in-memory collection. It's result is 0.
$post->revisions()->count();

// This will get all staged PostRevisions from the in-memory collection. It's result is a list of the 10 revisions.
$post->revisions->all();
// This makes a database query. It ignores the local in-memory collection. It's result is []
$post->revisions()->get();

Now lets save the post

// We create a non-persistent Model
$post = new App\Models\Post();
$post->save();
// This makes a query. It's result is zero because I just created the post, but it seems like an unnecessary call, and I'd like to not make it.
$post->revisions->count();
// This makes a database query. It's result is 0.
$post->revisions()->count();

// create 10 revisions
foreach(range(1, 10) as $number) {
    $revision = new \App\Models\PostRevision();
    $revision->post_id = $post->id;
    $post->revisions[] = $revision;
}

// This makes no query. It works with the in-memory collection. It's result is 10.
$post->revisions->count();
// This makes a database query. It ignores the local in-memory collection. It's result is 0.
$post->revisions()->count();

// This will get all staged PostRevisions from the in-memory collection. It's result is a list of the 10 revisions.
$post->revisions->all();
// This makes a database query. It ignores the local in-memory collection. It's result is []
$post->revisions()->get();

I am looking for a way to preserve the behaviour before the object is saved with the property based interactions.

if the relation is null then eloquent attempts to resolve the relation by querying the database (lazy loading)

You can prevent this if you wish

https://laravel.com/docs/8.x/eloquent-relationships#preventing-lazy-loading

In lieu of a setting, I'm going to do something to override the magic

<?php

namespace App\Models;

use Illuminate\Database\Eloquent\Factories\HasFactory;
use Illuminate\Database\Eloquent\Model;
use Illuminate\Support\Collection;

class Post extends Model
{
    use HasFactory;

    /** @var Collection */
    public $revisionsLocal;

    public function __construct() {
        $this->revisionsLocal = new Collection([]);
    }

    public function revisions() {
        return $this->hasMany(PostRevision::class);
    }
}

Now the revisions property cannot be magically overwritten, so it avoids the database and I can saveMany on the hasMany collection revisions(). :smile: I'm sure if I PR this Taylor would not be happy, but I think it's a better design. It also avoid's @snapey concerns over n+1 :wink:

Update: privoted to not override this behaviour, but introduce a new property for the logical behaviour.