Eloquent many to many relationship is always empty - php

Question

I know this question has been asked a lot but all answers didn't seem to work for me - or at least the questions I found were about the pivot table.
I have a many to many relationship (User - Appointment) which is joined by the pivot table "apointment_user", see migrations below.
Schema::create('appointment_user', function (Blueprint $table) {
$table->unsignedInteger('user_id')->nullable();
$table->foreign('user_id')->references('id')->on('users');
$table->unsignedInteger('appointment_id')->nullable();
$table->foreign('appointment_id')->references('id')->on('appointments');
$table->primary(['user_id','appointment_id']);
$table->timestamps();
});
Schema::create('appointments', function (Blueprint $table) {
$table->increments('id');
$table->string('title');
$table->dateTime('date');
$table->string('location');
$table->dateTime('departure');
$table->timestamps();
});
Schema::create('users', function (Blueprint $table) {
$table->increments('id');
$table->string('name');
$table->string('email')->unique();
$table->string('password');
$table->date('last_login')->nullable();
$table->rememberToken();
$table->timestamps();
$table->softDeletes();
});
class User extends Model {
protected $with = ['appointments'];
public function appointments() : BelongsToMany {
return $this->belongsToMany(Appointment::class);
}
}
class Appointment extends Model {
public function users() : BelongsToMany {
return $this->belongsToMany(User::class);
}
}
I have a user with the ID 1 and about 10 appointments, which I do attach to the relationship in a seeder. The pivot table has 10 records, as intended (User ID is always 1).
However, if I dump my User object using dd(User::find(1)), the relationship is always an empty collection. However, a 1:n relationship (between a role works well).
Does anybody see what I'm missing? Any help is appreciated.
Many thanks and kind regards
Edit
I just tried some other kind of dumping. I've simply returned my User-Object as JSON-response and there the relationship is filled with 10 appointments... strange.

Answer 1

Though it seems that your table and column names are as Laravel would guess, have you tried expliciting the names?
class User extends Model {
protected $with = ['appointments'];
public function appointments() : BelongsToMany {
return $this->belongsToMany(Appointment::class, 'appointment_user', 'user_id', 'appointment_id');
}
}
class Appointment extends Model {
public function users() : BelongsToMany {
return $this->belongsToMany(User::class, 'appointment_user', 'appointment_id', 'user_id');
}
}