laravel eloquent 'has' method behaves in an unexpected way - laravel

Question

I want to get the collection of a Section model if it has at least one User. from the docs the has() method does this, great. The collection retrieved does not have the the users relationship in it. Yet when I loop through the collection , I can get the properties of the users. Why?
class Section extends Model
{
protected $guarded = [];
public function users()
{
return $this->hasMany('App\User');
}
}
class User extends Authenticatable
{
protected $guarded = [];
public function section()
{
return $this->belongsTo('App\Section');
}
}
what I did is this:
$section = Section::where('id' , 1)->has('users')->get();
the collection is this:
Illuminate\Database\Eloquent\Collection {#3025
all: [
App\Section {#3015
id: 1,
class_id: 1,
section_name: "A",
created_at: "2019-12-14 18:26:01",
updated_at: "2019-12-14 18:26:01",
},
],
}
Now the weird part is that when I do the following, it gives the properties of users even though in the collection the users relationship is not present.
Why?
#foreach ($section as $section)
#foreach ($section->users as $student)
<p>{{$student->name}}</p>
#endforeach
#endforeach
solomon
uche
kene

Answer 1

This is just how Laravel works.
Accessing $model->{relationship}, in your case $section->users, is a magic function that checks if you have explicitly loaded the relationship via something like Section::with('users'), and if you haven't, loads it then.
The reason you're not seeing users when you run dd($section) is that you didn't explicitly load the relationship, but this does not mean that it is unavailable. If you included with('users') in your initial query, you'd see the following:
$section = Section::where('id' , 1)->has('users')->with('users')->get();
App\Section {#3015
id: 1,
class_id: 1,
section_name: "A",
created_at: "2019-12-14 18:26:01",
updated_at: "2019-12-14 18:26:01",
users: [
0 => App\User {#3016}
id: ...
name: ...
]
},
// Or similar
Basically, you weren't loading the relationship, so you aren't able to see it when using dd($section), but it is still available in PHP, due to Laravel's magic methods.
I should note as well, use the correct variable naming and closure (->get(), ->first(), etc) for your query.
$section is a poor name when using ->get(), as you're getting multiple records back from the database. Either use $sections, or change the closure to ->first(), and don't use a foreach() if you use ->first().

Answer 2

Looks like your first echo:
$section = Section::where('id' , 1)->has('users')->get();
Just prints the section where it has a user, but you're not specifically saying give me the users as well.
In the next loop you are looping over each section in the view, and specifically saying loop the relationship. this is visible by this line: #foreach ($section->users as $student)
Im reading the docs here: https://laravel.com/docs/6.x/eloquent-relationships#querying-relations
In your first echo when printing the section you can get the users like so: echo $section-> users()

Answer 3

Ok, now I understand your question.
First
The has method does not mean that it's going to include User. It means that will return all the sections that have at least one user. I think there is/are users for Section id ===1. So, in your code with has or without it, it does not make any difference.
if you want to load a relationship explicit you should use with
Section::where('id' , 1)->with('users')->get();. Then you should have users collection under per section.
Second
The reason why you can still access the user properties in your blade file, is because of lazy loading. even it's not included in the original DB query and result but when you are trying to access it laravel still tries to fetch those for you. And this may cause N+1 problem.