未定義オフセットを取得する：laravel

Question

私はLaravelを初めて使用しており、私の練習用に小さなアプリケーションを開発していました。私は就職活動をしています。このエラーは私に多くのトラブルを与え、私をたくさん混乱させます。

public function job_search(Request $request) { 
    $search_skill_set = $request->job_skills; 
    $search_results = JobPost::whereRaw('FIND_IN_SET(?, job_skills)', $search_skill_set) 
     ->get() 
     ->toArray(); 

    for ($i = 0; $i < count($search_results); $i++) { 
     $department_id = (int)$search_results[$i]['department_name']; 
     $department_name = Department::select('department_name') 
      ->where('id', '=', $department_id) 
      ->get() 
      ->toArray(); 

     // the next statement raises an Undefined:offset 1 error 
     $search_results[$i]['department_name_info'] = $department_name[$i]['department_name']; 
    } 
    var_dump($search_results); 
} 

私が間違っているのところ、私は与えられたスニペットから任意の提案やコード

Answer 1

変更のいずれかの変更がそう、この行なっていない午前：

$search_results[$i]['department_name_info'] = $department_name[0]['department_name']; 

に

$search_results[$i]['department_name_info'] = $department_name[$i]['department_name']; 

を

Answer 2

for ($i=0; $i < count($search_results) ; $i++) { 
    $department_id = (int)$search_results[$i]['department_name']; 

    //I am getting department id correct here 
    $department_name = Department::select('department_name')->where('id','=',$department_id)->get()->toArray(); 
    //$depratment_name is also going okay and working 

    $search_results[$i]['department_name_info'] = $department_name[0]['department_name']; 
    // This line should have a static index. 
}