Orwhere has method does not allow null - laravel

Question

enter image description hereI am trying to implement a many to many relationship search with 2 models.
i get input from multiple checkbox values and want to search for items that match A or B when there is an input of data.
I read this url and wrote the same logic.
https://laracasts.com/discuss/channels/laravel/many-to-many-relationship-with-2-pivot-table-data-search
public function search(Request $request)
{
$languages = $request->lang;
$fields = $request->field;
$agencies = Agency::with('languages')->with('specialized_fields')
->orWhereHas('languages', function($query) use ($languages) {
$query->whereIn('language_id', $languages);
})
->orWhereHas('specialized_fields', function($query) use ($fields) {
$query->whereIn('specialized_field_id', $fields);
})
->get();
dd($agencies);
}
i expected to achieve A or B search but instead I got this error.
Argument 1 passed to Illuminate\Database\Query\Builder::cleanBindings() must be of the type array, null given, called in /var/www/jtf/vendor/laravel/framework/src/Illuminate/Database/Query/Builder.php on line 907
it seems that it causes this error if either A or B is null, but why??? Does the OrWhereHas method work only when theres an input??
/added info/
my error message
my agency model
class Agency extends Model {
protected $guarded = [
'id'
];
public function languages(){
return $this->belongsToMany('App\Language');
}
public function specialized_fields(){
return $this->belongsToMany('App\SpecializedField');
}
public function region(){
return $this->hasOne('App\Region');
} }

Answer 1

I believe it's because either $languages or $fields is null.
Since ->whereIn() is expecting an array, but you're passing null.
You just need to make sure you're passing an array.
$languages = array_filter((array) $request->lang); // cast to array & remove null value
$fields = array_filter((array) $request->field);
$agencies = Agency::with('languages', 'specialized_fields')
->orWhereHas('languages', function($query) use ($languages) {
$query->whereIn('language_id', $languages);
})
->orWhereHas('specialized_fields', function($query) use ($fields) {
$query->whereIn('specialized_field_id', $fields);
})
->get();

Answer 2

I'm speculating that you started your where query chain with an orWhereHas() which may have caused the problem, try starting with whereHas() instead.
public function search(Request $request){
$languages = $request->lang;
$fields = $request->field;
$agencies = Agency::with('languages', 'specialized_fields') // you can get away by just using one with(), not needed but its cleaner this way
->whereHas('languages', function($query) use ($languages) { // previously orwherehas
$query->whereIn('language_id', $languages);
}) ->orWhereHas('specialized_fields', function($query) use ($fields) {
$query->whereIn('specialized_field_id', $fields);
})
->get();
dd($agencies);
}