[11.x] Added `for` method to Eloquent models

[ash-jc-allen]

Hey!

This PR proposes a new for method that helps set foreign keys on models. It's a fresh (and simplified!) take on my past attempt from a couple of years ago: https://github.com/laravel/framework/pull/42467

I think a major drawback of the previous approach was that it wasn't obvious whether for would be used in queries, or for setting fields on models. So it got a bit confusing!

In this approach, I've completely ditched the Builder side of things. Although on the surface, it looks like it would have been nice, I think it would have caused more issues than it solved! So, instead, the for method only exists on the Model classes.

So you can call it like so:

use App\Models\Comment;
use App\Models\Post;
use App\Models\User;

// Imagine these are from a request or something instead.
$post = Post::first(); // ID: 123
$user = User::first(); // ID: 456

// Before:
$comment = Comment::create([
    'comment' => 'hello',
    'post_id' => $post->id,
    'user_id' => $user->id,
]);

// After (using the "for" method):
$comment = Comment::make(['comment' => 'hello'])
    ->for($post)
    ->for($user);

$comment->save();

Assuming there is a posts and users relationship, the comment will now have the following data set:

'comment' => 'hello'
'post_id' => 123,
'user_id' => 456,

There's also the ability to specify the relationship name if needed:

Comment::make(['comment' => 'hello'])
    ->for($post, 'blogPost')
    ->for($user)
    ->save();

I also quite like how it almost reads like a human-readable sentence when it's written like this too:

new Comment()
    ->for($post)
    ->for($user)
    ->fill(['comment' => 'hello'])
    ->save();

Hopefully this is something that other devs would also find useful. Although it's a relatively small change, I like the way that it can reduce the likelihood of typos and also uses a similar syntax to model factories.

But I completely understand if it's not something worth merging in. I'd kick myself if I didn't try and scratch the itch though haha!

If it's something you might consider merging, please let me know if there's anything you might want me to change 😄

[Bosphoramus]

Yes, please! 🤩🤩

[caendesilva]

I love it. The implementation looks simple and easy to maintain, whilst the feature is very useful.

[osbre]

Wouldn't it be better if this was powered by actual relationship method assignments? So

$store->owner()->assign($user);

If I recall correctly

[ahinkle]

I can see the benefit, but it feels a bit ambiguous and might raise questions if I came across it while browsing the code—or for juniors who might struggle to decide which approach to use. The existing methods are a bit more explicit in their intent.

Cool idea though!

[ericwoelki]

Wouldn't it be better if this was powered by actual relationship method assignments? So

$store->owner()->assign($user);

If I recall correctly

You already can do $model->relation()->associate($related) for cases like this. Docs

[osbre]

@ericwoelki right, but we are talking about ->for($related) and its implementation details

[ericwoelki]

@osbre Fair, I was pointing out that the method is associate() rather than assign(). I agree with you that deferring to it behind the scenes for the proposed for() method could simply its implementation and also has the benefit of populating the relation.

[Mejvas]

This change makes sense because building relations in this way is already implemented in Illuminate\Database\Eloquent\Factories\Factory.

Already valid code for building eloquent models in tests (and best practice how to do it):

$post = Post::first();
$user = User::first();

$comment = Comment::factory()
    ->for($post)
    ->for($user)
    ->make(['comment' => 'hello']);