Not able to reference foreign key other than primary in Laravel - laravel

Question

I have two models: Departments and DepartmentTypes. In DepartmentTypes i have a column "depth" serving as foreign key to departments (field: hirarchy_lvl). That said, i am trying to get the DepartmentType label to be displayed in a view but keep on failing...
Here's what i have:
Department.php:
public function departmentType()
{
return $this->belongsTo(DepartmentType::class, 'depth', 'hirarchy_lvl');
}
DepartmentType.php
public function department()
{
return $this->hasMany(Department::class, 'hirarchy_lvl', 'depth');
}
db schema create:
public function up()
{
Schema::create('department_types', function (Blueprint $table) {
$table->bigIncrements('id');
$table->timestamps();
$table->bigInteger('depth')->unsigned()->unique();
$table->string('hirarchy_lvl_name');
});
DB::table('department_types')->insert(array('created_at' => now(), 'depth' => '10', 'hirarchy_lvl_name' => 'company'));
DB::table('department_types')->insert(array('created_at' => now(), 'depth' => '20', 'hirarchy_lvl_name' => 'department'));
DB::table('department_types')->insert(array('created_at' => now(), 'depth' => '30', 'hirarchy_lvl_name' => 'team'));
DB::table('department_types')->insert(array('created_at' => now(), 'depth' => '40', 'hirarchy_lvl_name' => 'individual'));
Schema::table('departments', function (Blueprint $table) {
$table->foreign('hirarchy_lvl')->references('depth')->on('department_types')->onDelete('NO ACTION')->change(); //shall reference other objective
});
}
In the controller:
public function listDepartmentsByHirarchy($hirLvl = 0){
if($hirLvl){
$departments = Department::where('hirarchy_lvl', $hirLvl)->get();
}
else
{
$departments = Department::get();
}
$department_types = DepartmentType::get();
return view('configcenter/listDepartments', compact('departments', 'department_types'));
}
Testing in the view:
<td>
{{$department}}
</td>
gives me:
{"id":2,"created_at":"2019-12-18 13:04:11","updated_at":null,"description":"dep1","parent_dep":{"id":1,"created_at":"2019-12-18 13:04:11","updated_at":null,"description":"company","parent_dep":1,"hirarchy_lvl":10},"hirarchy_lvl":20}
Leading me to the conclusion that the foreign key does not get resolved properly (as it's just the value rather than the object i would need over here).
Now, after studying the documentation (https://laravel.com/docs/5.4/eloquent-relationships#has-many-through) and several posts, i cannot help myself but ask the noobish question: how do i reference the foreign key properly so i can work on the object in the view?
appreciate any hint...

Answer 1

Your Department::departmentType() relationship is incorrect, I believe. The fields should be switched.
When defining the belongsTo side of the relationship, the second parameter is the field on the defining model (departments.hirarchy_lvl) and the third parameter is the field on the related model (department_types.depth).
When defining the hasOne/hasMany side of the relationship, it is the opposite. The second parameter is the field on the related model, and the third parameter is the field on the defining model.
Department.php:
public function departmentType()
{
return $this->belongsTo(DepartmentType::class, 'hirarchy_lvl', 'depth');
}
DepartmentType.php
public function department()
{
return $this->hasMany(Department::class, 'hirarchy_lvl', 'depth');
}