Stuck on search function for multiple parameters - php

Question

I have a page with multiple posts, each post has a location and department & title.
I implemented the search function for "word search" and it works fine, but in addition to this I have two Dropdown menus for location & department, they get their content from two different table.
I am kind of stuck and don't know why it doesn't work, here is my controller code:
public function index(Request $request)
{
$posts = Post::orderBy('titel')->get();
$standorts = Standort::orderBy('standort_name')->get();
$abteilungs = Abteilung::orderBy('abteilung_name')->get();
if ($request->filled('s') || $request->has('standort') || $request->has('abteilung')) {
$word = strtolower($request->get('s'));
$location = $request->standort;
$dep = $request->abteilung;
$query = strtolower($request->get('s'));
$posts = $posts->filter(function ($post) use ($dep, $word, $location) {
if (
Str::contains(strtolower($post->Titel), $word) ||
Post::where('standort_name') == $location
|| Post::where('abteilung_name') == $dep
) {
return true;
}
return false;
});
}
return view('posts.overview', [
'posts' => $posts,
'standorts' => $standorts,
'abteilungs' => $abteilungs,
]);
}
Here is my blade code:
<form class="mb-5 flex justify-left grid grid-cols-4 gap-x-20" action=" {{ route('overview') }}"
method="get">
<div class="w-full h-12 text-left col-start-1 col-end-1">
<input placeholder="Schlagwort" type="text" id="s" name="s" value="{{ request()->get('s') }}"
class="mb-2 w-full h-full bg-white bg-opacity-95 rounded focus:ring-2 border border-gray-300 focus:border-indigo-500 text-base outline-none text-gray-700 text-xl py-1 px-3 leading-8">
</div>
<div class="text-left mb-4 h-12">
<select name="abteilung" id="abteilung" class="h-full w-full flex justify-center bg-white bg-opacity-95 rounded focus:ring-2 border border-gray-300 focus:border-indigo-500 text-base outline-none text-gray-700 text-lg text-center leading-8">
<option selected="true" disabled="disabled">Abteilung</option>
#foreach($abteilungs as $abteilung)
<option value="{{ $abteilung->abteilung_name }}">{{ $abteilung->abteilung_name }}</option>
#endforeach
</select>
</div>
<div class="text-left mb-4 h-12">
<select name="standort" id="standort" class="h-full w-full flex justify-center bg-white bg-opacity-95 rounded focus:ring-2 border border-gray-300 focus:border-indigo-500 text-base outline-none text-gray-700 text-lg text-center leading-8">
<option selected="true" disabled="disabled">Standort</option>
#foreach($standorts as $standort)
<option value="{{ $standort->standort_name }}">{{ $standort->standort_name }}</option>
#endforeach
</select>
</div>
<button class="col-start-4 col-end-4 w-11/12 h-12 text-white text-2xl px-4 py-2 rounded text-base font-medium bg-gradient-to-r from-green-400 to-blue-500 float-right shadow transition duration-500 ease-in-out transform hover:-translate-y-1 hover:scale-100">
Suchen
</button>
</form>
When I dd this part:
$word = strtolower($request->get('s'));
$location = $request->standort;
$dep = $request->abteilung;
I get the correct attributes, for instance a word like "HR", a location like "Munich" and a department like "Finance".
When I perform the search though for a specific department all posts are gone.
Edit for clarity:
The goal is that a user can search for a word in a title, a location and department all in one request, and only the post where each is present gets shown.
Edit Relation Models:
Post Model:
class Post extends Model
{
use HasFactory;
/**
* The attributes that are mass assignable.
*
* #var string[]
*/
protected $fillable = [
'titel',
'startdate',
'enddate',
'beschreibung',
'standort',
'type_name',
'abteilung_name',
'kontakt',
'isActive',
'lebenslauf',
'zeugnisse',
'anschreiben',
'weitere_Doks',
'is_Permitted',
'job_start',
];
public function location() {
return $this->hasOne(Standort::class);
}
public function job_type() {
return $this->hasOne(Jobtypes::class);
}
}
Abteilung Model:
class Abteilung extends Model
{
use HasFactory;
/**
* The attributes that are mass assignable.
*
* #var string[]
*/
protected $fillable = [
'abteilung_name',
];
public function posts() {
return $this->hasMany(Post::class);
}
}
Standort Model:
class Standort extends Model
{
use HasFactory;
/**
* The attributes that are mass assignable.
*
* #var string[]
*/
protected $fillable = [
'abteilung_name',
];
public function posts() {
return $this->hasMany(Post::class);
}
}